✅ URI / UTI / STD / SEPSIS / TB Flashcards
💨 UPPER RESPIRATORY INFECTION
Usually viral syndrome that is benign and self-limited, lasting <strong>3 to 10 days</strong>. Viruses (eg, rhinovirus, coronavirus, respiratory syncytial virus, metapneumovirus) cause infection by gaining entrance to epithelial cells of the upper respiratory tract, leading to host inflammatory responses, cholinergic stimulation, vasodilation, and increased vascular permeability.
<strong>Tx:</strong> Inhaling heated vapor, such as steam from a hot shower, may decrease nasal symptoms. Other symptomatic measures include increasing fluid intake, gargling with salt water or using saline nasal spray, sucking on throat lozenges, and ensuring adequate rest. Although these measures lack good evidence of effectiveness, they are safe and inexpensive. For relief of nasal congestion, oral decongestants (eg, pseudoephedrine) or short-term (<3 days) use of topical nasal decongestants (eg, phenylephrine) is beneficial.
<strong>Rx:</strong> In patients with rhinorrhea and sneezing, a short course of a <strong>first-generation antihistamine diphenhydramine (Benadryl) </strong>or<strong> intranasal ipratropium</strong> may be considered. In patients with a productive cough and wheezing, an <strong>inhaled β-agonist </strong>may reduce the duration of cough. Acetaminophen or an nonsteroidal anti-inflammatory drugs (eg, naproxen, ibuprofen) may be used for headache, myalgia, and malaise.
🦠 Pneumonia
A space occupying lesion without volume loss; caused by bacteria, viruses, mycoplasmae and fungi.
Ddx: Airspace filling not distinguishable radiographically: fluid (inflammatory), cells (cancer), protein (alveolar proteinosis) and blood (pulmonary hemorrhage).
Dx: The x-ray findings of pneumonia are airspace opacity, lobar consolidation, or interstitial opacities. There is usually considerable overlap.
Lobar - classically Pneumococcal pneumonia, entire lobe consolidated and air bronchograms common. Abrupt in onset, with fever, pleuritic chest pain, and purulent sputum production.
An “Air bronchogram” is a tubular outline of an airway made visible by filling of the surrounding alveoli by fluid or inflammatory exudates.
Ddx: air bronchograms: Lung consolidation (PNA), pulmonary edema, nonobstructive pulmonary atelectasis, severe interstitial disease, neoplasm, and normal expiration.
Lobular - often Staphlococcus, multifocal, patchy, sometimes without air bronchograms
Interstitial - Viral or Mycoplasma; latter starts perihilar and can become confluent and/or patchy as disease progresses, no air bronchograms. “Ground Glass” is a radiology descriptive term (used in both chest radiographs and CT imaging) to indicate that blood vessels are not obscured as would be the case in alveolar lung opacities. Both atypical bacterial and viral organisms may produce pneumonias that differ radiographically from more common bacteria such as pneumococcus. They may produce a ground glass appearance and increased interstitial markings. The CXR appearance of Pneumocystis pneumonia is typically bilateral, diffuse interstitial (“reticular”) or ground glass opacities.
Hx: “Atypical pneumonia” due to C pneumoniae or 🏒M. pneumoniae: Patients often complain of a sore throat at the beginning of the illness and a protracted course of symptoms. Physical examination is often unimpressive compared to radiograph findings and the diagnosis is often not made as the course is often indistinguishable from other lower respiratory infections.
💨Aspiration - follows gravitational flow of aspirated contents; impaired consciousness, post anesthesia, common in alcoholics, debilitated, demented patients; anaerobic (Bacteroides and Fusobacterium). In a supine patient who has aspirated, the common locations of pneumonia are the posterior segment of the upper lobe and superior segment of the lower lobe. The superior segment of the right lower lobe is the segment most likely to develop aspiration pneumonia.
Diffuse pulmonary infections - Community acquired (Mycoplasma, resolves spontaneoulsy) nosocomial immunocompromised host (bacterial, fungal, PCP)
🏥 Nosocomial by definition occur 3 days after admission. Patients in the ICU are often relatively immunocompromised secondary to their primary disease and are subject to iatrogenic factors which increase their sucseptabilty to pneumonia-causing pathogens. These include the following: endotracheal tubes, which defeat many patient defense mechanisms; medications used to reduce gastric acid, which may promote bacterial growth in the stomach; and the use of antibiotics, which may selectively encourage the growth of some pathogenic bacteria. Nosocomial pneumonias are often polymicrobial and caused by 🔮gram-negative enteric pathogens. The offending organisms often include Pseudomonas species, E-coli, Klebsiella species, and Proteus species (Pseudomonas, debilitated, mechanical vent pts, high mortality rate, patchy opacities, cavitation, ill-defined nodular).
Ventilator-associated pneumonia (VAP) is a type of nosocomial pneumonia that usually develops >48 hours after endotracheal intubation. It is most commonly caused by aerobic gram-negative bacilli (eg, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and gram-positive cocci (eg, methicillin-resistant Staphylococcus aureus, Streptococcus). Patients usually have fever, purulent secretions, difficulty with ventilation (eg, increased respiratory rate, decreased tidal volume), and leukocytosis. Those with an abnormal chest x-ray (eg, alveolar infiltrates, air bronchograms, silhouetting of adjacent solid organs) require lower respiratory tract sampling (ie, tracheobronchial aspiration) for microscopic analysis (Gram stain) and culture
🌆 Community-acquired pneumonias, which usually are caused by 🏮 gram-positive species
Dx:
The radiographic appearance of pneumonia may be difficult to differentiate from atelectasis or early ARDS. Classically, pneumonia first appears as patchy opacifications or ill-defined nodules. It is often multifocal and bilateral, occurring most often in the gravity dependent areas of the lung. This feature makes it difficult to distinguish from atelectasis or pulmonary edem. E-coli and pseudomonas species can rapidly involve the entire lung. Their symmetric pattern often simulates pulmonary edema. The presence of patchy air space opacities, air bronchograms, ill-defined segmental consolidation or associated pleural effusion support the diagnosis of pneumonia. Occassionally, in gram-negative pneumonias small luciencies may be found within consolidated lung which may represent unaffected acini or areas of air trapping. This is particularly likely to occur in patients with underlying COPD. However, these must be distinguished from lucencies created by cavitation and abscess formation.
Cx: Complications of nosocomial pneumonias can have severe consequences and require immediate attention. Unlike community acquired pneumonia, pleural effusions caused by gram-negative organisms are more likely to represent empyema and therefore require drainage. Other complications of nosocomial pneumonias include lung abscess formation and bronchopleural fistulas.
In consolidative pneumonia, the alveoli become filled with inflammatory exudate, leading to marked impairment of alveolar ventilation in that portion of the lung. The result is right-to-left intrapulmonary shunting, which describes perfusion of lung tissue in the absence of alveolar ventilation, an extreme form of ventilation/perfusion (V/Q) mismatch (V≈0). A characteristic of intrapulmonary shunting is inability to correct hypoxemia with increased concentration of inspired oxygen (FiO2). Other causes of V/Q mismatch (eg, emphysema, interstitial lung disease, pulmonary embolism) allow for correction of hypoxemia with an increase in FiO2 because V > 0. In practice, increased FiO2 typically leads to some improvement in hypoxemia in patients with pneumonia because only a portion of the lung is being affected by intrapulmonary shunting.
🏇🏿 Pneumococcal Pneumonia
α-Hemolytic streptococci
🏇🏿Streptococcus Pneumonia
💪🏿PR/MDR Pneumococcal Pneumonia
Hx: Age >65 y, β-lactam therapy (in previous 3 mo), alcoholism, immunosuppression (illness, glucocorticoids), multiple medical comorbidities, exposure to a child in a day care center.
Dx: CA-MRSA or compatible sputum Gram stain
Tx: Add vancomycin or linezolid to β-lactamb plus either azithromycin or a fluoroquinolone.
Patients with bacteremic pneumococcal pneumonia should be discharged on oral amoxicillin to complete 7 days of therapy.
Organizing pneumonia
Subacute illness (4-6 wk) with fever and alveolar infiltrates (often peripheral). Diagnosis is based on biopsy (transbronchial or open lung) or characteristic clinical picture and response to glucocorticoids.
Pneumocystis pneumonia (PCP)
Clinical
- Indolent (HIV) or acute respiratory failure (immunocompromised)
- Fever, dry cough, ↓ oxygen levels
HIV infection with a low CD4 count is the biggest risk factor; however, patients taking 🌚chronic glucocorticoids (especially in combination with other immunosuppressant medications) are at significant risk.
Workup
- ↑ LDH level
- Diffuse reticular infiltrates on imaging
- Induced sputum or BAL (stain)
Treatment
- TMP-SMX
- Prednisone if ↓ oxygen levels
Prevention
- TMP-SMX
- Antiretrovirals (in HIV)
Hx: Subacute onset of dyspnea on exertion, hypoxia, nonproductive cough; diffuse interstitial infiltrates on chest radiograph
Dx: Chest x-ray usually shows bilateral interstitial infiltrates. Hypoxia out of proportion to the radiographic findings is also suggestive. Serum lactate dehydrogenase levels are frequently elevated. The diagnosis is confirmed by demonstration of the organism in sputum or bronchoalveolar lavage aspirate.
Tx: Trimethoprim-sulfamethoxazole (TMP-SMX) is the initial drug of choice for the treatment of PCP regardless of pneumonia severity. Treatment typically lasts for 21 days. Adjunctive corticosteroids have been shown to decrease mortality in cases of severe PCP (possibly by reducing inflammation due to dying organisms). Indications for corticosteroid use include partial pressure of oxygen (PaO2) <70 mm Hg or an alveolar-arterial (A-a) gradient >35 mm Hg on room air. This patient has a PaO2 of 54 mm Hg on room air, indicating the need for corticosteroid use.
🌆 Community Acquired Pneumonia (CAP)
🏇🏽Streptococcus pneumoniae causes the majority of cases, likely due to increased rates of colonization and impaired immunity against encapsulated bacteria.
Dx: Sputum gram stain and Culture. A Gram stain that shows gram-positive lancet-shaped diplococci intracellularly is good evidence for pneumococcal infection.“Rusty sputum” is classic for pneumococcal pneumonia but may not always be present.
Severe CAP, defined as CAP in a patient who requires admission to an intensive care unit or transfer to an intensive care unit within 24 hours of admission. Blood cultures, Legionella and Streptococcus pneumoniae urine antigen assays, and endotracheal aspirate for Gram stain and culture are recommended for hospitalized patients with severe CAP.
IDSA/ATS Minor Criteria for Severe Community-Acquired Pneumonia
Clinical Criteria
- Confusion (new-onset disorientation to person, place, or time)
- Hypothermia (core temperature <36.0°C [96.8°F])
- Respiration rate ≥30 breaths/mina
- Hypotension necessitating aggressive fluid resuscitation
- Multilobar pulmonary infiltrates
Px: When a portion of the lung is consolidated (eg, lobar pneumonia), the density of tissue/fluid increases and dullness to percussion is detected. In addition, sound conducts more rapidly through the consolidated lung, resulting in increased intensity of breath sounds and a more prominent expiratory component. More rapid sound conduction also results in increased tactile fremitus as well as egophony (sounds like the letter “A” when the patient says the letter “E”) in areas of lung consolidation. Crackles are also often heard.
Laboratory Criteria
- Arterial PO 2/FIO 2 ratio ≤250a
- Leukopenia (<4000 cells/µL )
- Thrombocytopenia (<100,000 platelets /µL)
- Blood urea nitrogen >20 mg/dL
CURB-65 Identifies ❗high-risk patients and to predict a complicated course. Patients who meet at least two criteria are usually admitted to the hospital (mortality rate 8.3%), and those with at least three criteria are considered for intensive care unit (ICU) admission (mortality rate 20%).
Confusion, blood Urea nitrogen >20 mg/dL, Respiration rate ≥30 breaths/min, systolic Blood pressure <90 mm Hg OR diastolic blood pressure <60 mm Hg, and age ≥65 years)
Tx: Pneumococcal 💉vaccination is recommended for all patients with HIV to reduce the risk of invasive S pneumoniae disease. Empirical antibiotic therapy becomes more difficult in community-acquired pneumonia as more pathogens a re recognized and as the pneumococcus develops resistance to penicillin, macrolides, and even quinolones.
(Outpatient): 🐦Macrolide (azithromycin, clarithromycin, or erythromycin) or doxycycline
Risk factor(s) for drug-resistant S. pneumoniae or underlying comorbidities
Respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin) or β-lactam plus a macrolide or doxycycline
Tx: (Inpatient):
Medical ward
β-lactam plus a macrolide or doxycycline; or respiratory fluoroquinolone (eg, moxifloxacin, gemifloxacin or levofloxacin)
Intensive care unit
β-lactam plus either azithromycin or a fluoroquinolone; if penicillin allergic, a respiratory fluoroquinolone plus aztreonam
Modifying Factors That Increase the Risk of Infection With Specific Pathogens
Age >65 y, β-lactam therapy (in previous 3 mo), alcoholism, immunosuppression (illness, glucocorticoids), multiple medical comorbidities, exposure to a child in a day care center
Penicillin-resistant and drug-resistant pneumococci
Residence in an extended care facility, underlying cardiopulmonary disease, multiple medical comorbidities, recent antibiotic therapy
Enteric gram-negative bacteria
Pseudomonas aeruginosa 🛀🏿
Structural lung disease (bronchiectasis), glucocorticoids therapy, broad-spectrum antibiotic therapy for >7 d; malnutrition
Dx: 🧞♀️Pseudomonas aeruginosa or 🏮gram-negative rods on sputum Gram stain
Tx: Antipseudomonal β-lactam with pneumococcal coverage (eg, cefepime, imipenem, meropenem, or piperacillin-tazobactam) ➕ ciprofloxacin or levofloxacin (750 mg) OR antipseudomonal β-lactam with pneumococcal coverage plus an aminoglycoside plus azithromycin; or antipseudomonale β-lactam with pneumococcal coverage plus an aminoglycoside plus a respiratory fluoroquinolone
Endobronchial obstruction (tumor)
Anaerobes, Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus
💉Intravenous drug use
Anaerobes, S. aureus, Mycobacterium tuberculosis, S. pneumoniae
Influenza epidemic in the community
Influenza virus, S. pneumoniae, S. aureus, H. influenzae
COPD, 🚬 smoking history
S. pneumoniae, H. influenzae, Moraxella catarrhalis, P. aeruginosa, Legionella species, Chlamydophila
Poor 🦷dental hygiene, aspiration, lung abscess
Oral anaerobes
Animal exposure
Coxiella burnetii (farm animals); Chlamydophila psittaci, Cryptococcus (birds); Histoplasma (birds, bats)
PR/MDR 💪🏿Pneumococcal Pneumonia
Hx: Age >65 y, β-lactam therapy (in previous 3 mo), alcoholism, immunosuppression (illness, glucocorticoids), multiple medical comorbidities, exposure to a child in a day care center.
Dx: CA-MRSA or compatible sputum Gram stain
Tx: Add 🚐vancomycin OR 🚧 linezolid to β-lactamb ➕ either 🐦azithromycin or a fluoroquinolone.
Patients with bacteremic pneumococcal pneumonia should be discharged on oral amoxicillin to complete 7 days of therapy.
Sinusitis
Rhitnitis
Hx: Facial pain, headache, pressure that incresaes when bending forward, purulent nasal discharge, pus in the nasal cavity, unilateral sinus pain or tenderness, maxillary toothache.
Allergic rhinitis is present in at least 60% of people with recurrent sinusitis.
Dx: sinus CT is rarely necessary (12 weeks)
Tx: Largely symptomatc;
First-generation antihistamine (diphenhydramine)[Benadryl]
Intranasal antihistamine (azelastine, olopatidine)
Intranasal glucocorticoids (Fluticasone [Flonase],
Topical decongestants (Afrin; oxymetazolam) have all been shown to be helpful. Topical decongestants should be limited to a few days of use to avoid rebound rhinitis (rhinitis medicamentosa).
Also try: sinus rinses, inhalation oh humidified air, and adequate hydration.
Criteria for Abx:
- symptoms for 10-14 days
- colored discharge
- sinus pain
Purulent rhinorrhea, purulent secretions in the nasal cavity, tooth pain, and a biphasic history (worsening of symptoms after an initial period of improvement) have been found to be associated with bacterial sinusitis.
Acute bacterial rhinosinusitis
Clinical features
- Cough, nasal discharge
- Fever
- Face pain/headache
Diagnostic criteria (1 of 3)
- Persistent symptoms ≥10 days without improvement
- Severe onset (fever ≥39 C [102.2 F] + drainage) ≥3 days
- Worsening symptoms following initial improvement
Treatment
- Amoxicillin ± clavulanate
Viral URI symptoms typically self-resolve in 7-10 days. In contrast, ABRS is diagnosed by any 1 of the following 3 criteria:
- Symptoms (eg, cough, congestion) persist for ≥10 days without improvement.
OR
- Symptoms severe in onset (fever ≥39 C [102.2 F] + drainage) for ≥3 days.
OR
- Symptoms worsen following initial improvement (ie, biphasic illness). Fever may be absent.
Most cases are due to nontypeable Haemophilus influenzae or Streptococcus pneumoniae. Worsening symptoms (eg, progressive cough ± fever), as seen in this patient, are treated with oral antibiotics (eg, amoxicillin ± clavulanate) at the time of diagnosis. In contrast, in patients with persistent but not worsening symptoms and a milder course, oral antibiotics or a 3-day period of observation for clinical improvement are both acceptable treatment options.
Cx:
Untreated ABRS can lead to life-threatening complications such as periorbital/orbital cellulitis due to orbital extension as well as meningitis or brain abscess due to intracranial extension.
Intracranial complications should be suspected in patients with persistent headache and early-morning vomiting, which occurs due to increased intracranial pressure in the recumbent position. Other findings may include altered mental status (eg, drowsiness), neck pain (suggestive of meningeal irritation), and focal neurologic deficits.
The next step in management is urgent imaging of the brain, orbits, and sinuses. Although MRI is more sensitive, CT scan is faster and can detect early cerebritis; a ring-enhancing lesion confirms the diagnosis. Treatment is intravenous antibiotics and surgical drainage.
Influenza
Influenza virus is largely a winter infection that attacks the epithelium of the upper and lower respiratory tract. Approximately 1-5 days after exposure, patients abruptly develop systemic (fever, malaise, myalgias, headache) and upper/lower respiratory (rhinorrhea, sore throat, nonproductive cough) symptoms. Physical and laboratory examinations are often normal but may show pharyngeal erythema (without exudates) and mild alterations in leukocyte count (low early, high later). Most patients recover spontaneously and completely within 1 week of symptom onset. However, patients with advanced age (>65) and chronic medical illness (eg, coronary artery disease, diabetes mellitus) are far more likely to develop complications.
Sudden onset of high fever (body temperature >39°C [102°F]), severe myalgia, and headache.
Coryza, body temperature up to 41.0°C (105.8°F), myalgia, headache, and sore throat.
Severity of symptoms associated with high fever and myalgia suggest influenza.
Outbreak: In institutional settings such as nursing homes, outbreaks are likely to be particularly severe. Thus, prophylaxis is extremely important in this setting. All residents should receive the influenza vaccine unless they have known egg allergy (patients can choose to decline the vaccine). Since protective antibodies to the vaccine will not develop for 2 weeks, oseltamivir can be used for protection against influenza A during the interim 2-week period. Because of increasing resistance, amantadine is no longer recommended for prophylaxis. The best way to prevent influenza-associated pneumonia is to prevent the outbreak in the first place.
Cx: Pneumonia is the most common complication of influenza and is the result of either secondary bacterial infection (eg, Streptococcus pneumoniae) or direct viral attack (influenza pneumonia). Patients with primary influenza pneumonia typically have an acute worsening of symptoms (dyspnea, cough), leukocytosis (although <15,000/mm3), hypoxia, and bilateral, diffuse interstitial infiltrates on chest x-ray.
Tx: Hospitalization with supplemental oxygen support and antiviral (eg, oseltamivir) treatment is usually required. Influenza may also cause complications in the muscle (myositis, rhabdomyolysis), heart (myocarditis, pericarditis), and central nervous system (encephalitis, transverse myelitis).
Adults at high risk for influenza complications
- Age >65
- Women who are pregnant & up to 2 weeks postpartum
- Underlying chronic medical illness (eg, chronic pulmonary, cardiovascular, renal, hepatic)
- Immunosuppression
- Morbid obesity
- Native Americans
- Nursing home or chronic care facility residents
Actinomycosis
Characterized by cough, hemoptysis, and (eventually) draining sinuses. Has an indolent course; patients may have respiratory symptoms for up to 5 mo before diagnosis. Sulphur granules are seen in stained specimens from draining sinuses.
Blastomycosis
Blastomycosis is a fungal infection that occurs most often in the vicinity of the Great Lakes, 🗺 Mississippi river and Ohio River basins (Wisconsin has the highest infection rate). The pulmonary symptoms and chest x-ray findings of
Blastomycosis presents with signs and symptoms of chronic respiratory infection.
Systemic Blastomycosis may cause characteristic raised, ulcerated skin lesions and lytic bone lesions. The skin lesions in exposed areas become crusted, ulcerated, or verrucous.
Aspergillus
A ubiquitous fungus that most people encounter daily. Conidia are inhaled into the lung and convert to potentially pathogenic hyphae. Patients with immunocompetency rapidly clear the organism and rarely develop infection; however, a subset of immunocompetent patients with a history of pulmonary disease (eg, cavitary tuberculosis) may develop chronic pulmonary aspergillosis (CPA) at sites of lung damage. Diagnosis is made by the presence of all 3 of the following:
>3 months of symptoms - fever, weight loss, fatigue, cough, hemoptysis, and/or dyspnea
Cavitary lesion(s) containing debris, fluid, or an aspergilloma (fungus ball)
Positive Aspergillus IgG serology
Tx: Therapy depends on symptoms and severity of disease; antifungal medication (eg, itraconazole, voriconazole), surgery (to prevent hemoptysis), and bronchial artery embolization (for hemoptysis with extensive disease) may be used together or separately.
Histoplasmosis
Histoplasmosis is an endemic mycosis of the central and midwestern United States that rarely causes illness in immunocompetent individuals but may occasionally cause subacute pulmonary symptoms (<5%).
Histoplasma capsulatum (present as mold in soil and in bird and bat droppings) is endemic to the Mississippi and Ohio River basins. In an appropriate epidemiologic setting, pulmonary histoplasmosis should be considered when pulmonary symptoms are accompanied by mediastinal or hilar lymph nodes (or masses) or by arthralgias and erythema nodosum.
Cx: ❗ Disseminated histoplasmosis in immunocompromised patients can present with lymphadenopathy, pancytopenia, and hepatosplenomegaly as the organism targets histiocytes and the reticuloendothelial system.
Caseating granulomas are most common, but non-caseating granulomas may be the only finding. Careful fungal tissue stains and culture, along with Histoplasmaurinary antigen testing, are used for diagnosis.
Small dose inoculation is rarely symptomatic (<5% become ill); patients who inhale larger doses (eg, exposure in enclosed areas such as a cave) are at higher risk for symptomatic infection. Symptoms usually present 2-4 weeks after exposure with subacute fever, chills, malaise, headache, myalgias, and dry cough.
Chest x-ray typically reveals mediastinal or hilar lymphadenopathy (LAD) with focal, reticulonodular, or miliary infiltrates (depending on the degree of exposure).
Diagnosis is usually made with Histoplasma antigen testing of the urine or blood, plus serology. Some patients may require tissue diagnosis, which often reveals granulomas with narrow-based budding yeasts. Most cases resolve completely (over weeks) without intervention. For patients with moderate or severe disease, oral itraconazole or intravenous liposomal amphotericin B can be used.
Dx: Chest radiography may show a miliary (eg, histoplasmosis) or cavitary lesion.
Coccidioides
Coccidioides is an endemic mold of the desert southwest whose spores are easily aerosolized in the dry months after a rainy season. Inhalation of a single arthroconidium is sufficient to cause infection (usually 7-14 days after inoculation). Symptoms may be subclinical, but many patients (>50%) develop community-acquired pneumonia (CAP) (fever, chest pain, productive cough, lobar infiltrate) often accompanied by arthralgias, erythema nodosum, or erythema multiforme. This clinical syndrome is also called Valley Fever, and symptoms frequently last weeks or months.
Diagnosis should be suspected in any patient living in or traveling to an endemic region (particularly Arizona or California) who has a lower respiratory illness lasting >1 week. Confirmation primarily relies on serologic testing, but cultures are often sent.
Tx: Most patients who are otherwise healthy and have mild or moderate disease do not need antifungal treatment and can have regular follow-up to ensure resolution. However, patients with severe disease or certain risk factors (eg, HIV, immunosuppressive medications, diabetes mellitus) are much more likely to develop dissemination (bones, central nervous system, skin); these patients require antifungal treatment (eg, ketoconazole, fluconazole).
👩🏿🚒Adrenal crisis
Allergic rhinitis
Seasonal nasal symptoms, including clear rhinorrhea and watery, itchy eyes. Patients may have a history of asthma.
Behçet disease
Behçet disease is an uncommon systemic disease with genital ulcers as one component; the ulcers are often painful. Other features include recurrent oral aphthous ulcers, uveitis, pathergy, arthritis, gastrointestinal manifestations, and central nervous system disease. In Behçet disease, serologic tests for syphilis will be negative.
Campylobacter spp.
Poultry, raw milk, travel history
Reactive arthritis can occur after Shigella, Salmonella, and Campylobacter infections.
Guillain-Barré syndrome is associated with Campylobacter and Yersinia infections.
💊 Cephalosporins
First generation Active against most gram-positive cocci (including penicillinase-producing staphylococci).
Cefazolin (Ancef, Kefzol) IV
Cephalexin (Keflex, Biocef, Keftab) PO
Second generation greater activity against certain gram-negative bacilli; specifically, one subgroup of second-generation cephalosporins has enhanced activity against H. influenzae
Cefuroxime (Kefurox, Zinacef)
Cefotetan (Cefotan)
Cefoxitin (Mefoxin)
Third generation The third-generation cephalosporins are less active against most gram-positive organisms than the first-generation cephalosporins. Highly active against Enterobacteriaceae (E. coli, Proteus mirabilis, indole-positive Proteus, Klebsiella, Enterobacter, Serratia, Citrobacter), Neisseria, and H. influenzae. They are the therapy of choice for gram-negative meningitis due to susceptible Enterobacteriaceae.
Ceftriaxone (Rocephin) has the longest serum half-life of this group (6.4 hours) and can be administered once or twice a day.
Cefotaxime (Claforan)
Ceftazidime (Fortaz) 🧞♀️
Fourth generation
Cefepime (Maxipime) 🧞♀️
Advanced generation and combination agents
Ceftaroline (Teflaro) improved gram-positive activity. activity against MRSA,
Fluoroquinolones
Fluoroquinolones upregulate cell matrix metalloproteases, leading to increased collagen degradation; this mechanism is likely responsible for several associated adverse effects, including Achilles tendon rupture, retinal detachment, and aortic aneurysm rupture.
The increased risk of aortic aneurysm rupture with fluoroquinolones is small overall, but it warrants serious consideration due to the high morbidity and mortality of rupture. Hence, when possible, these drugs should be avoided in patients with known aortic aneurysm or substantial risk factors for aortic aneurysm (eg, Marfan syndrome, Ehlers-Danlos syndrome, advanced atherosclerotic disease, uncontrolled hypertension).
Other adverse effects of fluoroquinolones that are likely unrelated to collagen degradation include encephalopathy, peripheral neuropathy, and QT-interval prolongation.
🦠 Chlamydia / Gonorrhea
Acute cervicitis is most commonly caused by Chlamydia trachomatis and Neisseria gonorrhoeae. Infection by these pathogens is most prevalent in women age <25. Acute cervicitis is diagnosed clinically by a pelvic examination that shows a mucopurulent discharge and a friable cervix (eg, bleeds easily on contact). Treatment is empiric with azithromycin and ceftriaxone, but nucleic acid amplification testing should also be performed for infection confirmation.
Risk factors
- Age <25
- High-risk sexual behavior
Manifestations
- Asymptomatic (most common)
- Cervicitis
- Urethritis
- Perihepatitis (Fitz-Hugh-Curtis syndrome)
Mucopurulent cervicitis with exacerbation during and after menstruation is classic gonorrhea.
Diagnosis
- Nucleic acid amplification testing
Treatment
- Empiric: 🐦Azithromycin + 🔨ceftriaxone (Rocephin)
- Confirmed Gonorrhea: 🐦Azithromycin + 🔨ceftriaxone OR 🌼 floroquinolone
- Confirmed Chlamydia: 🐦Azithromycin OR 🎡Doxycycline (Ceftriaxone is NOT for Chlamydia)
- Azithromycin 1 g orally, given in a single dose or doxycycline 100 mg orally twice daily for 7 d
👓 Spectinomycin is the treatment of choice for pregnant women who have asymptomatic N. gonorrhoeae infections and who are allergic to penicillin. 🐓 Erythromycin is another drug that is effective.
Complications
- Pelvic inflammatory disease
- Ectopic pregnancy
- Infertility
- Pharyngitis
Tx:
Gonorrhea would be described as a ⚪ clearer cervical discharge (“not so mucopurulent”) and excluded by a gram stain with culture.
Chlamydia generates a mucopurulent 💛 yellow cervical discharge
Disseminated gonococcal infection
Disseminated gonococcal infection
- Purulent monoarthritis OR Triad of tenosynovitis, dermatitis, migratory polyarthralgia
Diagnosis
- Detection of Neisseria gonorrhoeaein urine, cervical, or urethral sample
- Culture of blood, synovial fluid (less sensitive)
Treatment
- 3rd-generation cephalosporin IV AND oral azithromyci
Migratory joint symptoms and often have involvement of several joints with tenosynovitis.
Skin lesions are found in more than 75% of patients with DGI but may be few in number; consequently. Lesions are most likely to be found on the extremities. The classic lesion is characterized by a small number of necrotic vesicopustules on an erythematous base.
Dx: Nucleic acid amplification urine test (NAAT) for Neisseria gonorrhoeae is a noninvasive, sensitive test for diagnosing gonorrhea in men. This test provides rapid results (within hours) and can help to guide therapy pending return of blood and synovial fluid culture results.
Mucosal cultures, including of the throat, anus, urethra, or cervix (in women), may also be helpful in establishing the diagnosis.
Tx: Infection of cervix, urethra, or rectum:
Ceftriaxone 125 mg IM, given in a single dose, PLUS either azithromycin 1 g orally in a single dose or doxycycline 100 mg orally twice daily for 7 days
Trachoma
Trachoma is due to Chlamydia trachomatis serotypes A, B, and C and is the leading cause of blindness worldwide. C trachomatis spreads effectively in crowded or unsanitary conditions. The active phase is most common in children and is characterized by follicular conjunctivitis and pannus (neovascularization) formation in the cornea. There is often a concomitant nasopharyngeal infection (eg, rhinorrhea, pharyngitis). Repeated or chronic infection leads to scarring of the eyelids and inversion of the eyelashes (trichiasis). Over time, the lashes rub on the eye and cause ulcerations and blindness (cicatricial trachoma).
The diagnosis can be made clinically by examination of the tarsal conjunctivae. C trachomatis may be visible by Giemsa stain examination of conjunctival scrapings. Oral azithromycin is effective against C trachomatis; in general, the entire region (eg, village, refugee camp) should be treated simultaneously. For individuals with trichiasis, eyelid surgery is needed to preserve vision.
Reactive arthritis
Reactive arthritis is a type of seronegative spondyloarthropathy. Reactive arthritis occurs in both men and women, and enthesitis and oligoarthritis are common.
Classic reactive arthritis consists of a triad of nongonococcal urethritis, asymmetric oligoarthritis and conjunctivitis. The arthritis often involves the knee and sacroiliac spine.
Hx: The classic triad of arthritis, urethritis, and conjunctivitis occurs in only about one third of patients.
Manifests within 2 months of an episode of bacterial gastroenteritis or n_ongonococcal urethritis_ or cervicitis in a genetically predisposed patient.
Reactive arthritis was previously called Reiter syndrome, which referred to the coincidence of arthritis, conjunctivitis, and urethritis (or cervicitis). However, only about one third of patients have all three symptoms.
Reactive arthritis usually affects the peripheral joints, often in the lower extremities, although inflammatory back pain also may be present.
Patients may also present with heel pain with enthesitis; keratoderma blennorrhagicum on the palms or soles; or circinate balanitis on the penis.
Differs from rheumatoid arthritis in that it is oligoarticular and asymmetric?
Presents as symmetric? inflammatory oligoarthritis, most often involving weight-bearing joints; may include tendon insertion inflammation (enthesitis).
Extra-articular manifestations include conjunctivitis, urethritis, stomatitis, and psoriaform skin changes (hyperkeratotic lesions on the palms and soles). Infection with Salmonella, Shigella, Yersinia, Campylobacter, or Chlamydia species within 3 wk prior to onset of initial attack.
Synovial fluid analysis is usually sterile. 🧯 Nonsteroidal anti-inflammatory agents (NSAIDs) are the first line therapy during the acute phase of this condition.
🐱 Congenital Toxoplasmosis
Toxoplasmosis, a protozoal infection caused by T. gondii
Risk factors
- Undercooked (or cured) meat (particularly common in Europeans)
- Unwashed produce
- Unprotected handling of cat feces (hosts the protozoan oocytes).
Ultrasound findings
- Bilateral ventriculomegaly
- Diffuse intracranial calcifications
Clinical features
- Chorioretinitis
- Hydrocephalus
- Seizures
- Intellectual disability
- Sensorineural hearing loss
Maternal infection can be asymptomatic, but those with symptoms typically have mild fever and a diffuse, nonpruritic, maculopapular rash that resolves spontaneously in a few days. Although the infection is mild in mothers, transplacental (vertical) transmission can occur and result in devastating fetal infection. T gondii preferentially destroys fetal neural tissue, which results in the ultrasound findings of bilateral ventriculomegaly and intracranial calcifications (particularly within the basal ganglia). Additional ultrasound findings may include low birth weight, hepatosplenomegaly, jaundice, anemia, neurological disease
with seizures, intracranial calcifications, and mental retardation.
Diagnosis
- Maternal: Serology
- Fetal: Amniotic fluid PCR
Fetal patients with the above clinical findings undergo amniocentesis for T gondii polymerase chain reaction testing of amniotic fluid.
Treatment
- Spiramycin
Prenatal antitoxoplasma therapy (eg, spiramycin, pyrimethamine/sulfadiazine/folinic acid) may decrease the risk of neurologic sequelae (eg, chorioretinitis, seizures, intellectual disability).
Coxsackievirus
Coxsackievirus
can produce a morbilliform vesiculopustular rash, often with a hemorrhagic component and with lesions of the throat, palms, and soles.
Cryptococcus neoformans
Cryptococcus neoformans, an encapsulated yeast. Most cases are seen in patients with AIDS who have CD4 counts <100/mm2.
C neoformans replicates in the central nervous system and clogs the arachnoid villi with yeast components and capsular polysaccharides, leading to CSF outflow obstruction and increased intracranial pressure (ICP). Therefore, patients often develop progressive headaches, nausea/vomiting, and confusion.
Cx: In approximately 25% of cases, elevated ICP compresses the 6th cranial nerve (abducens nerve), leading to lateral gaze palsy and diplopia. Patients also frequently have fever, malaise, and umbilicated skin lesions that resemble molluscum contagiosum (due to hematogenous dissemination to the skin).
Brain imaging is usually normal but may show signs of increased ICP such as enlarged ventricles. The diagnosis is generally made with lumbar puncture (LP), measurement of CSF pressure, analysis of CSF, and capsular polysaccharide antigen testing or India ink stain. Management is with antifungal therapy. In addition, although caution should be exercised when performing an LP in the setting of increased ICP, patients with cryptococcal meningitis often require frequent (eg, daily) LPs and sometimes ventricular drains to decrease ICP.
Diagnosis is established through cryptococcal antigen testing of cerebrospinal fluid (CSF). CSF India Ink stain or culture on Sabouraud agar may also identify the organism. Other features include an elevated opening pressure, low glucose, high protein, and a lymphocytic pleocytosis (although white cells may be reduced in HIV patients). Increased intracranial pressure develops due to the occlusion of CSF flow by the organism. Neuroimaging is performed to exclude mass lesions, although C neoformans infection rarely causes mass lesions in patients with HIV. If no such lesion is found, a lumbar puncture can be performed; it both provides diagnostic confirmation and offers therapeutic value in the relief of elevated intracranial pressure. Some patients require serial lumbar punctures in addition to antifungal therapy to control intracranial pressure.
Cryptosporidiosis
Acute or chronic watery diarrhea in an immunocompromised patient; outbreak in a nursing home or day care center or on a cruise ship
1–8 d
Dengue fever
Dengue fever is characterized by fever, severe frontal headache, retro-orbital pain, and severe musculo-skeletal and lumbar back pain. A macular or scarlatiniform rash develops within 3 to 4 days of the illness. Virtually all cases respond to conservative measures with bleeding, hepatitis, and myositis reported as potential
rare complications.
Symptoms typically develop 4-7 days (and almost never >2 weeks) following the mosquito bite.
Dengue hemorrhagic fever is a more severe form of the disease. It is more common among infants and elderly people. It is characterized by increased
vascular permeability with hypovolemic shock and thrombocytopenia with spontaneous ecchymoses and mucosal bleeding. Dengue is a mosquito-borne illness.
Chikungunya
Chikungunya virus infection is more likely to cause high fever, severe arthralgia, arthritis, rash, and lymphopenia, whereas dengue virus infection is more likely to cause neutropenia, thrombocytopenia, hemorrhage, shock, and death. The diagnosis of dengue fever is established via polymerase chain reaction (PCR) or serology.
💩💩💩💦Diarrhea
Infectious (Acute) Diarrhea:
The most common cause of acute diarrhea is an infectious agent (>90% of cases).
Dx: Stool culture: Used selectively because of low yield (<3%);detects Salmonella, Shigella, and Campylobacter spp.; specify if needed to test for Escherichia coli O157:H7 (if visible or occult blood)
Stool ova and parasites: Microscopic examination for Giardia, Entamoeba, Cryptosporidium, Cyclospora, and Isospora spp. and microsporidia if suspected
Stool enzyme immunoassays: Detect Shiga toxins 1 and 2 and antigens for Giardia, Entamoeba, Campylobacter, Cryptosporidium spp. if suspected
Tx: For acute viral diarrhea, adults should be encouraged to eat potatoes, rice, wheat, noodles, crackers, bananas, yogurt, boiled vegetables, and soup. Dairy products, alcohol, and caffeine should be avoided.
Oral rehydrating solutions can be used if vomiting is a problem, and fasting is not indicated. Some fruit juices can exacerbate diarrhea.
Diarrhea is defined as more than three loose stools per day.
Diarrhea can be divided into 3 main categories: watery, fatty, and inflammatory.
Watery diarrhea can be further broken down into osmotic, secretory, and functional.
Secretory diarrhea include larger daily stool volumes (>1 L/day) and diarrhea that occurs even during fasting or sleep. Secretory diarrhea most commonly occurs when luminal ion channels are disrupted in the gastrointestinal tract, resulting in a state of active secretion.
Many patients confuse true diarrhea with three other conditions: pseudodiarrhea (the frequent passage of small volumes of stool), fecal incontinence, and overflow diarrhea caused by fecal impaction.
Acute diarrhea is present for less than 14 days, persistent diarrhea has been present for at least 14 days but 4 weeks or less, and diarrhea is considered to be chronic if it has been present for more than 4 weeks.
Although the vast majority of episodes of acute diarrhea are caused by viruses and are self-limited, further clinical evaluation is indicated in those who have bloody stools, body temperature greater than 38.5°C (>101.3°F), significant abdominal pain, severe diarrhea causing symptomatic dehydration, recent antibiotic use, a history of inflammatory bowel disease, or immunocompromised states; food handlers; the elderly; or pregnant women.
Because most episodes of diarrhea are self-limited, diagnostic testing generally is reserved for patients with severe diarrheal illness characterized by fever, blood in the stool, or signs of dehydration (weakness, thirst, decreased urine output, orthostasis) or patients with diarrhea lasting >7 days.
Echinococcus granulosus
Humans contract the infection from close and intimate contact with 🐶 dogs, which are the definitive host in the tapeworm’s lifecycle. E granulosus typically causes unilocular cystic lesions that can occur in any organ (eg, liver, lung, muscle, bone); smaller daughter cysts may be present. Multiple lesions are usually associated with E multilocularis (rather than E granulosus) infection.
Most hydatid cysts are diagnosed incidentally when patients are being evaluated for other problems (eg, fatty food intolerance likely from cholelithiasis). However, these cysts can cause symptoms due to compression on surrounding tissues. Imaging techniques and serologic testing can be used for diagnosis. “Eggshell” calcification of a hepatic cyst on CT scan is highly suggestive of a hydatid cyst.
Many patients remain asymptomatic for years and develop clinical illness only due to large cyst size (>10 cm) or rupture. Manifestations include right upper quadrant pain, nausea, vomiting, and hepatomegaly. Rupture may result in fever. Ultrasound has excellent sensitivity (~95%) and typically shows a large, smooth hepatic cyst often with daughter cysts (internal septations). Positive serology for E granulosusIgG corroborates the diagnosis (sensitivity ~95%) and usually obviates the need for percutaneous biopsy. Small cysts (<5 cm) are typically treated with albendazole; larger or complex cysts usually also require percutaneous therapy or surgery.
Treatment is generally surgical resection under the cover of albendazole. In some situations, aspiration can be performed, although there is a risk of anaphylactic shock due to cyst content spillage.
Entamoeba histolytica
Entamoeba histolytica is a protozoan common in developing countries and is transmitted through consumption of contaminated food and water. Approximately 10% of patients have clinical manifestations of colitis or extraintestinal (liver, pleura, brain) disease. Amebic liver abscess develops when E histolyticaspreads from the colonic mucosa to the liver via the portal vein.
Risk factors
- Developing nations (travel/residence)
- Contaminated food/water
- Fecal-oral sexual transmission (rare)
Manifestations
- 90% of patients asymptomatic
- Colitis (diarrhea, bloody stool with mucus, abdominal pain)
- Liver abscess (RUQ pain, fever)
- Complications - rupture to pleura/peritoneum
Symptoms usually occur 2 to 5 months after travel to an endemic area. Diarrhea usually occurs first but has usually resolved before the hepatic symptoms develop. The most common presentation for an amebic liver abscess is abdominal pain, usually RUQ.
Diagnosis
- Stool ova & parasites, stool antigen testing (colitis)
- E. histolytica serology (liver abscess)
- An indirect hemagglutination test is a sensitive assay and will be positive in 90% to 100% of patients.
- 🔊 Ultrasound has 75% to 85% sensitivity and shows abscess with well-defined margins.
Treatment
- Metronidazole & intraluminal antibiotic (eg, paromomycin)
Symptoms are subacute and include right upper quadrant (RUQ) pain and fever, sometimes with recent or concurrent bloody diarrhea (colitis). The pain is often dull and can be referred to the right chest wall or shoulder. Systemic symptoms (eg, anorexia, weight loss, cough) can occur, and hepatomegaly and elevations in leukocyte count, alkaline phosphatase, and transaminases are common. As with other protozoal infections (eg, giardiasis), peripheral eosinophilia is not a frequent finding (in contrast to many helminthic infections, which can stimulate IL-5 production). A characteristic imaging finding is a single, subcapsular, low-density lesion in the right lobe of the liver (due to greater portal blood supply compared with the left). Diagnosis is made with serology; needle aspiration is generally unnecessary.
Enteroadherent:
(Infecting organisms adhere to the gastrointestinal mucosa and compete with normal bowel flora)
Enterohemorrhagic E. coli
Ground beef, raw vegetables
12–72 h
Enteroinvasive (Bacterial Enteritis)
(Infecting organisms invade and destroy intestinal mucosa, resulting in bloody diarrhea)
Minimal Inflammation
Enteroinvasive E. coli
Routine stool culture cannot distinguish pathogenic E. coli from normal fecal flora. Therefore, in the setting of blood in the stool, test specifically for E. coli O157:H7
If symptoms have persisted beyond 7 days, stool should be examined for ova and parasites.
Enterotoxigenic Escherichia coli
Hx: Salads, cheese, meats
8–72 h
Tx: Although prophylactic antibiotics are not recommended for traveler’s diarrhea, empiric antibiotics (quinolones) may be appropriate for patients with symptoms. Untreated traveler’s diarrhea usually resolves in 3 to 5 days, but treatment can improve symptoms and shorten the course.
Enterotoxin
(Toxins produced by intestinal microbes that act directly on secretory mechanisms in the intestinal mucosa, causing watery diarrhea).
Approximately one-third of travelers to underdeveloped countries will develop travelers’ diarrhea. Of those, 40% will
alter their plans because of the symptoms, 20% will be bed-bound for at least 1 day, and 1% will require hospitalization. Most cases of travelers’ diarrhea are due to
enterotoxigenic E coli.
Tx: The antibiotic of choice for travelers’ diarrhea is a fluoroquinolone (ciprofloxacin, ofloxacin, or norfloxacin) with trimethoprim/sulfamethoxazole
or azithromycin being acceptable alternatives.
Epiglottitis
Epiglottitis is a rare, potentially fatal infection that presents with acute onset of fever, sore throat, and signs of upper airway obstruction (eg, stridor, drooling).
Severe sore throat with a benign-appearing oropharynx. Adults may have dyspnea, drooling, and stridor. Obtain urgent otolaryngology consultation, and do not attempt to examine the throat. A lateral neck film may show an enlarged epiglottis (“thumbprint sign”). Because of
the possibility of impending airway obstruction, the patient should be admitted to an intensive care unit for close monitoring. The most likely organism causing this infection is H influenzae.
X-ray is not required for diagnosis if clinical suspicion is high, but lateral view shows an enlarged epiglottis, suggestive of edema. Diagnosis is confirmed via direct visualization of an edematous epiglottis. However, detailed oropharyngeal examination is often deferred in children due to risk of laryngospasm from provoked aggravation. Direct laryngoscopy during intubation (a controlled setting to secure the airway) is often preferred for diagnosis and management.
Fever of unknown origin (FUO)
Fever of unknown origin (FUO) is applied when significant fever (usually defined as > 38.3°C or > 101°F) persists without a known cause after an adequate evaluation.
Systemic Inflammatory Disorders
One of the more common vasculitides is temporal arteritis, which can present as FUO in adults aged >50 years, even in the absence of the classic symptoms of headache, jaw claudication, or polymyalgia rheumatica. Other vasculitides (eg, granulomatosis with polyangiitis [Wegener granulomatosis]) and systemic inflammatory disorders (eg, systemic lupus erythematosus, adult-onset Still disease) should also be considered.
Malignancy
The most common FUO-associated malignancy is non-Hodgkin lymphoma. Renal cell carcinoma, any malignancy that metastasizes to the liver, and leukemia are other common causes.
Drug fever: Antibiotics can cause or prolong fever, creating confusion for the clinician. A common cause of drug fever is sulfonamide and β-lactam antibiotics and nitrofurantoin.
Dx:
Complete blood cell count with differential, peripheral blood smear
Comprehensive metabolic panel
Urinalysis and microscopy
Chest radiography
Blood and urine cultures
Antinuclear antibody and rheumatoid factor testing; ESR and total CRP
HIV antibody testing
For selected patients:
Viral serology in patients with mononucleosis-like syndrome (cytomegalovirus, heterophil)
Q fever serology (if exposure to farm animals)
Hepatitis serology (if abnormal liver enzyme levels)
Food Poisoning
Nausea and vomiting within 1 to 6 hours of consumption of food are caused by preformed toxins of B cereus and S aureus or heavy metals like copper or zinc.
Abdominal cramps and diarrhea that develop more than 8 hours after a meal are caused by C jejuni, E coli, Salmonella, Shigella, and Vibrio parahaemolyticus. It takes more than 8 hours for the bacteria to proliferate in the gut and initiate the infection. Watery diarrhea can also be caused by enterotoxigenic E coli, V cholerae, and Norovirus. Yersinia enterocolitica can cause fever and abdominal cramps without diarrhea—a presentation closely resembling acute appendicitis. Cryptosporidiosis, cyclosporiasis, and giardiasis cause diarrhea that can persist for 1 to 3 weeks.
Gastroenteritis
The Norwalk virus, reoviruses, and adenoviruses are common causes.
Generally, these illnesses are self-limited, and will resolve within 5 days.
Genital Herpes
Both HSV-1 and HSV-2 can cause primary genital infection, and the incidence of primary infection from HSV-1 has increased in recent years. HSV-1 genital infections are less likely to be associated with recurrences and subclinical viral shedding.
Dx: Confirmed by viral culture or polymerase chain reaction testing.
Tx: First clinical episode of genital herpes:
Acyclovir 400 mg orally three times daily for 7-10 d OR
Acyclovir 200 mg orally 5 times daily for 7-10 d OR
famciclovir 250 mg orally three times daily for 7-10 d OR
valacyclovir 1 g orally twice daily for 7-10 d
In recurrent HSV outbreaks, antiviral therapy is ideally started within 24 hours of onset and continued for 5 days.
🍑🍆 Genital Lesion
Genital warts and genital herpes are more common in
heterosexuals, with bacterial vaginosis being more common in lesbians. There is a mistaken belief that lesbians are not at risk for acquiring HIV. However, it has been shown that sexually active lesbians have a higher prevalence of HIV than women who have sex exclusively with men.
Giardia lamblia
Giardia duodenalis (sometimes noted as G lamblia or G intestinalis) is common in rural areas and developing countries, and has an incubation period of 1-2 weeks. It is most commonly transmitted by contaminated water but can be foodborne or transmitted person-to-person via a fecal-oral route.
Most patients are asymptomatic; however, a significant minority of those who do develop clinical illness may go on to develop chronic giardiasis characterized by malabsorption, weight loss, or persistent gastrointestinal distress.
Dx: The preferred confirmatory test for giardiasis is a stool antigen assay (direct immunofluorescence or ELISA). Stool microscopy for oocysts and trophozoites can also identify the organism and is useful in resource-poor settings or if other parasitic organisms are suspected. Some facilities also offer a nucleic acid amplification assay.
Tx: Metronidazole is the preferred treatment. Asymptomatic carriers do not usually need treatment. Patients who are not treated are at high risk for chronic malabsorption. 🍼 Lactose intolerance (due to brush border disruption) and fatty acid malabsorption (which causes the oily, malodorous stools) are the most common sequelae. Chronic malabsorption can lead to profound weight loss and vitamin deficiencies.
Cx: During the acute phase, giardiasis causes histologic changes in the small intestine (eg, disruption of the microvilli on enterocytes). This results in malabsorption and subsequent loose, oily stools; weight loss; and flatulence.
Heat Stroke
The first sign of serious heat stroke is the absence of sweating and warm, dry skin. Fans, cooling blankets, ice packs, cold intravenous fluids, and oxygen are used; for severe hyperthermia, cold gastric and peritoneal lavage is also used.
The findings of acute confusion, hyperthermia, tachycardia, and persistent epistaxis after exertion under direct sunlight are suggestive of exertional heat stroke. Heat stroke is defined by core temperature >40 C (104 F) and central nervous system dysfunction (eg, altered mental status).
Helminths
1–8 d
Herpes Zoster / Varicella
💥 Pain
Acute herpetic neuralgia
- Persists ≤30 days from rash onset
- NSAIDs, analgesics
Subacute herpetic neuralgia
- Persists >30 days but resolves within 4 months of rash onset
- NSAIDs, analgesics
Postherpetic neuralgia
- Persists >4 months from rash onset
- Tricyclic antidepressants, gabapentin, pregabalin
Acute zoster (shingles) is due to reactivation of the varicella zoster virus (VZV) and causes transient pain due to hemorrhagic inflammation of the sensory nerve. As viral replication diminishes, the skin lesions resolve and the pain typically fades; however, persistent pain for >4 months indicates PHN.
PHN occurs in approximately 5% of patients with shingles. The risk is greatest in those with advanced age, severe initial pain, or severe rash. The pain may be constant or intermittent and is typically associated with allodynia (pain elicited by nonpainful stimuli [eg, light touch]). Physical examination often reveals sensory abnormalities (eg, anesthesia, hyperesthesia) in the affected dermatome.
PHN often improves over time, but resolution may take years and the severity of pain usually warrants pharmacologic treatment. Anticonvulsants (primarily gabapentin and pregabalin) and tricyclic antidepressants (eg, amitriptyline) are the best-established drugs. Topical capsaicin and lidocaine are options for patients with mild to moderate pain. Opioids (eg, oxycodone) are also effective but are not preferred due to the expected duration of treatment and potential for dependence and abuse.
Cx: Varicella pneumonia develops in about 20% of adults with chickenpox. It occurs 3 to 7 days after the onset of the rash. The hallmarks of the chickenpox rash are papules, vesicles, and scabs in various stages of development. Fever, malaise, and itching are usually part of the clinical picture.
HIV
Hx: Symptoms of immunologic dysfunction, weight loss, generalized lymphadenopathy, fever and night sweats of >2 weeks’ duration, oral thrush, severe aphthous ulcers, severe seborrheic dermatitis, or oral hairy leukoplakia. Herpes zoster in a younger person, recurrent pneumonia, chronic diarrhea, or unexplained hematologic abnormalities (eg, anemia, leukopenia, thrombocytopenia, polyclonal gammopathy) should also prompt consideration of HIV infection.
In most cases, when HIV infection develops, an acute symptomatic illness occurs within 2 to 4 weeks of infection. Symptoms typically last for a few weeks and range from a simple febrile illness to a full-blown mononucleosis-like syndrome.
Dx:
HIV antibody antibody enzyme immunoassay (EIA)[ELISA] is the appropriate first test when screening for HIV infection.
Western blot assay if the EIA result is positive, this test has 99% sensitivity and specificity for the diagnosis of HIV infection. May occur and may diagnose HIV as early as 2 weeks after infection occurs. If negative, no further testing is indicated. If positive, supplemental testing is performed to determine virus type present (HIV-1 or HIV-2). If this follow-up testing is equivocal, HIV-1 nucleic acid testing is indicated.
Patients who present with symptomatic acute HIV infection (acute retroviral syndrome) are usually in the “window period,” which may extend for 3 to 6 weeks. During this time, seroconversion of the disease has not yet occurred and results of HIV antibody testing are negative.
Nucleic acid (NAAT)[HIV RNA][Viral specific test] are usually positive at quite high levels during this time frame and can be used to establish the diagnosis.
Dx: Routine monitoring of HIV-RNA and CD4 cell counts can be performed every 3 to 6 months in clinically stable patients with suppressed viral load.
Tx: Suppression of HIV viral load to less than 50 copies/mL should occur by 24 weeks of effective therapy. Virologic failure is suspected when suppression of viral replication to < 200 copies/mL cannot be achieved or maintained.
Cx:
Mucocutaneous candidiasis: Involves primarily the oropharynx and esophagus 200
Cryptococcosis: Cryptococcus neoformans is an invasive fungus acquired by the inhalation of spores that primarily causes pulmonary disease. Immunocompromised patients can develop central nervous system infection leading to meningoencephalitis. The classic presentation is indolent (eg, progressing over days to weeks), and neck stiffness and photophobia are absent in the majority of patients. Causes subacute ⛑ meningitis; often associated with cryptococcemia 100. Diagnosis is established through cryptococcal antigen testing of cerebrospinal fluid (CSF). CSF India Ink stain or culture on Sabouraud agar may also identify the organism.
Cryptosporidiosis: Persistent watery diarrhea
Cytomegalovirus is a common opportunistic pathogen in patients with AIDS who have very low CD4 counts (<50/mm3). It typically attacks the retina and the neurologic and gastrointestinal systems. Gastrointestinal CMV presents with fatigue, low-grade fever, weight loss, and frequent, low-volume stools that are often bloody. The diagnostic test of choice is a colonoscopy with biopsy (eosinophilic intranuclear and basophilic intracytoplasmic inclusions). Active CMV infection is treated with ganciclovir, although improvement and cure is unlikely if the patient does not also receive antiretroviral therapy. In all patients with active CMV, an ocular examination is required to rule out concurrent retinitis.
Kaposi sarcoma: Nontender, raised discrete purplish lesions, often on the lower extremities or intraoral; primarily in homosexual men coinfected with human herpesvirus 8. The color changes from light brown, to pink, to dark violet.
Lymphoma: Burkitt, large B-cell NHL, or primary CNS lymphoma
Mycobacterium tuberculosis: Pulmonary infection. Extrapulmonary manifestations more common if CD4 count <200 (0.20). Plx: Isoniazid and pyridoxine. Alternative: Weekly isoniazid and rifapentine direct observed therapy if not on ART when Induration of ≥5 mm on purified protein-derivative skin test or a positive interferon-γ release assay.
M. avium complex: Disseminated infection, often with liver and bone marrow involvement and diffuse adenopathy. Plx: Weekly 🐦azithromycin when CD4 count <50/µL
Pneumocystis pneumonia: Subacute onset of dyspnea on exertion, hypoxia, nonproductive cough; diffuse interstitial infiltrates on chest radiograph
Dx: Chest x-ray usually shows bilateral interstitial infiltrates. Hypoxia out of proportion to the radiographic findings is also suggestive. Serum lactate dehydrogenase levels are frequently elevated. The diagnosis is confirmed by demonstration of the organism in sputum or bronchoalveolar lavage aspirate.
Tx: Trimethoprim-sulfamethoxazole (TMP-SMX) is the initial drug of choice for the treatment of PCP regardless of pneumonia severity. Treatment typically lasts for 21 days. Adjunctive corticosteroids have been shown to decrease mortality in cases of severe PCP (possibly by reducing inflammation due to dying organisms). Indications for corticosteroid use include partial pressure of oxygen (PaO2) <70 mm Hg or an alveolar-arterial (A-a) gradient >35 mm Hg on room air. This patient has a PaO2 of 54 mm Hg on room air, indicating the need for corticosteroid use. Plx: Daily trimethoprim-sulfamethoxazole DS when CD4 count <200/µL (0.20 x 109/L).
Progressive multifocal leukoencephalopathy: Caused by JC virus (a human polyomavirus); white matter lesions seen on imaging; patient presents with focal neurologic defects including altered mental status
Toxoplasmosis: Fever, headache, focal neurologic deficits; multiple ring-enhancing lesions on CNS imaging; positive toxoplasma serology
Dx: All patients newly diagnosed with HIV should be tested for latent infection with serology for T gondii IgG antibody. If serology is positive and CD4 count is <100/mm3, primary prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) reduces the risk of toxoplasmosis dramatically (to 0%-2%).
Tx: Plx: Daily trimethoprim-sulfamethoxazole DS when CD4 count <100/µL (0.10 x 109/L) and toxoplasma seropositive. Patients on antiretroviral treatment can discontinue TMP-SMX when CD4 count is >200/mm3 for 3 months (and there is adequate viral suppression). TMP-SMX is also used for primary prophylaxis against Pneumocystis pneumonia.
Acyclovir or valacyclovir can be used to prevent herpes simplex virus recurrences. It is used for patients with severe or frequent recurrences (secondary prophylaxis) regardless of CD4 count. This patient is not experiencing recurrences. Fluconazole is effective therapy for candidiasis.
Bacillary angiomatosis is caused by Bartonella, a Gram-negative bacillus. Bright red, firm, friable, exophytic nodules in an HIV infected patient are most likely bacillary angiomatosis. Tx: Oral erythromycin is the antibiotic of choice.
Tx: Preferred initial combination therapy for treatment-naïve patients usually involves a “backbone” that consists of two nucleoside/nucleotide reverse transcriptase inhibitors. (The fixed combination of emtricitabine/tenofovir is often a first choice.) The backbone is combined with a “base” that consists of either a nonnucleoside reverse transcriptase inhibitor (typically efavirenz), an integrase strand transfer inhibitor (typically raltegravir), or one of two “boosted” protease inhibitors (typically atazanavir or darunavir combined with a second protease inhibitor ritonavir, which boosts the levels of the first by inhibiting the cytochrome P-450 system).
Side effect profile:
Nucleoside/nucleotide reverse transcriptase inhibitors: Lactic acidosis, hepatic toxicity, lipoatrophy, pancreatitis, peripheral neuropathy
Abacavir (preferred drug): Life-threatening hypersensitivity reaction, increased risk of myocardial infarction. Screen for HLA-B*5701 to reduce risk of hypersensitivity reaction.
Emtricitabine (preferred drug): Lactic acidosis, severe hepatic steatosis
Tenofovir (preferred drug): Nephrotoxicity: renal injury, Fanconi syndrome; osteopenia/osteoporosis
Nonnucleoside reverse transcriptase inhibitors: Hepatotoxicity, skin rash
Efavirenz (preferred drug): Sleep disturbance, depression, vivid dreams or hallucinations, possible teratogenicity
Rilpivirine: Rare rash
Protease inhibitors: GI upset (diarrhea), lipodystrophy, hepatotoxicity, dyslipidemia
Atazanavir (preferred drug): Jaundice (indirect hyperbilirubinemia), cholelithiasis, nephrolithiasis
Darunavir (preferred drug): Hypersensitivity reaction (especially those with sulfa allergy)
Fusion inhibitors: Enfuvirtide: Injection site reactions (itching/swelling/erythema), severe reactions, (sometimes with eosinophilia and signs of allergy)
Coreceptor antagonists: Maraviroc
Cough, fever, upper respiratory infections, rash, hepatotoxicity, musculoskeletal symptoms. Perform co-receptor tropism assay prior to use.
Integrase inhibitors: Raltegravir (preferred drug): Generally well tolerated. Commonly: headache, nausea, diarrhea. Rarely: rhabomyolysis, hypersensitivity reaction, depression
Dolutegravir: Headache, insomnia, hypersensitivity reaction
💉 All patients with HIV should receive the inactivated vaccines (influenza, tetanus-diphtheria-pertussis) recommended for the general population as well as those recommended specifically for people with HIV (pneumococcal, hepatitis B).
Patients with HIV should receive the following additional vaccines due to elevated risk:
- Vaccination for hepatitis A is recommended for adults who are at increased risk of contracting the virus such as men who have sex with men and travelers to countries where hepatitis A is prevalent (eg, contaminated food or water consumption). It is also recommended for adults who have conditions (eg, chronic liver disease) that increase the risk for severe complications. In the United States, the hepatitis A vaccine became part of routine childhood vaccinations in 2006
- They should receive vaccination for hepatitis B unless they have documented immunity.
- They also should receive vaccination for Streptococcus pneumoniae with the 13-valent pneumococcal conjugate vaccine (PCV13), followed by the 23-valent pneumococcal polysaccharide vaccine (PPSV23) 8 weeks later and again in 5 years and at age 65.
- Many experts also recommend varicella (ie, chickenpox) vaccine for adults with HIV born after 1979 who do not have evidence of immunity, provided that their CD4+ count is >200/mm3.
- ❗ Patients with HIV with CD4 counts <200/mm3 should NOT receive live attenuated vaccinations (varicella, zoster, measles-mumps-rubella [MMR]).
- The meningococcal vaccine, including boosters every 5 years, is recommended for all patients with HIV.
Cx: HIV-associated dementia usually affects deep gray matter structures and causes subacute cognitive, behavioral, and motor deficits. Imaging reveals cerebral atrophy with ventricular enlargement.
Progressive multifocal leukoencephalopathy
Epidemiology
- JC virus reactivation
- Severe immunosuppression (eg, untreated AIDS)
Manifestations
- Slowly progressive
- Confusion, paresis, ataxia, seizure
Diagnosis
- CT brain – white matter lesions with no enhancement/edema
- Lumbar puncture - CSF PCR for JC virus
- Brain biopsy (rarely needed)
Treatment
- Often fatal
- If HIV – antiretroviral therapy
PML is a life-threatening neurologic disease that is caused by the reactivation of JC virus. JC virus is usually acquired in childhood and lies dormant in the kidneys and lymphoid tissue; most individuals remain asymptomatic, but those with severe immunocompromise (eg, HIV with CD4 count <200/mm3) are at risk for reactivation. Reactivated virus spreads to the central nervous system (CNS) and lyses oligodendrocytes, causing white matter demyelination.
Symptoms include altered mental status, motor deficits, ataxia, and vision abnormalities (eg, diplopia). CT of the brain with contrast usually reveals nonenhancing, hypodense white matter lesions with no surrounding edema. Diagnosis requires lumbar puncture with cerebral spinal fluid evidence of JC virus (by PCR). Brain biopsy is occasionally required. Patients with AIDS are treated with antiretroviral therapy; this may prevent death, but significant neurologic impairment often remains.
HIV during pregnancy
HIV management during pregnancy
Antepartum
- HIV RNA viral load at initial visit, every 2-4 weeks after initiation or change of therapy, monthly until undetectable, then every 3 months
- CD4 cell count every 3-6 months
- Resistance testing if not previously performed
- ART initiation as early as possible
- Avoid amniocentesis unless viral load ≤1,000 copies/mL
Intrapartum
- Avoid artificial ROM, fetal scalp electrode, operative vaginal delivery
- Viral load ≤1,000 copies/mL: ART + vaginal delivery
- Viral load >1,000 copies/mL: ART + zidovudine + cesarean delivery
Postpartum
- Mother: Continue ART
- Infant (maternal viral load ≤1,000 copies/mL): Zidovudine
- Infant (maternal viral load >1,000 copies/mL): Multi-drug ART
The most important intervention for preventing the spread of HIV from mother to child is administration of combination antiretroviral therapy to the mother throughout pregnancy. Antiviral therapy should be initiated as soon as possible during pregnancy (even during the first trimester), regardless of maternal CD4 count or viral load. Antenatal combination therapy is the best way to suppress maternal HIV and prevent transplacental or perinatal acquisition by the infant. Mothers with undetectable viral loads at delivery have <1% risk of transmitting the infection to their infants. The 3-drug regimen should consist of 2 nucleoside reverse transcriptase inhibitors (NRTIs) plus a non-nucleoside reverse transcriptase inhibitor or a protease inhibitor. An NRTI with good placental transfer (eg, zidovudine, tenofovir) should be administered. Zidovudine should be administered to the neonate for >6 weeks.
Hypersensitivity pneumonitis
Recurrent episodes of fever and dyspnea, with rapid resolution of infiltrates; chronic infiltrates after multiple episodes. Diagnose with precipitating antibodies to the antigen (molds etc.), characteristic history, or open lung biopsy.
Infective Endocarditis
Hx: Injection drug use, recent procedures associated with risk of transient bacteremia, presence of a prosthetic valve, and certain cardiac abnormalities. Rheumatic fever
Symptoms suggesting septic emboli in patients with tricuspid valve endocarditis include shortness of breath, chest pain, and cough. Blindness, focal weakness, localized back or flank pain, hematuria, and gangrenous skin lesions may be embolic manifestations of left-sided infective endocarditis.
Px: New cardiac murmur, new-onset heart failure, focal neurologic signs, splenomegaly, and cutaneous manifestations (eg, petechiae, splinter hemorrhages). The presence of Osler nodes (violaceous, circumscribed, painful nodules found in the pulp of the fingers and toes) or Janeway lesions (painless, erythematous, macular lesions found on the soles and palms.
Dx: Leukocytosis, normocytic normochromic anemia, electrocardiographic conduction defects (atrioventricular block from extension of infection into the conduction system), hematuria, and low serum complement levels (eg, glomerulonephritis). CRX suggesting heart failure or septic emboli from right-sided endocarditis (eg, multiple bilateral small nodules on chest radiograph) raise suspicion for infective endocarditis.
Laboratory data include an elevated erythrocyte sedimentation rate. The ECG shows evidence of first-degree AV block. An antistreptolysin O antibody is necessary to document prior streptococcal infection.
Evidence of recent streptococcal infection plus two major manifestations or one major and two minor manifestations satisfy the Jones criteria for diagnosis of acute rheumatic fever.
Major criteria include ❤ carditis, polyarthritis, s. chorea, erythema marginatum, and subcutaneous nodules.
Minor manifestations include fever, polyarthralgia (Joints) elevated erythrocyte sedimentation rate, and PR prolongation on ECG.
💙 DUKE
Definite endocarditis = 2 MAJOR criteria OR 1 major + 3 minor criteria OR 5 minor criteria
Possible endocarditis = 1 major + 1 minor criterion or 3 minor criteria
DUKE MAJOR Criteria for Dx:
- Microbiologic (Bacteremia) - any of the following:
Typical microorganisms grown from 2/2 blood cultures
Staphylococcus aureus - Prosthetic valves, Intravascular catheters, Implanted devices (eg, pacemaker/defibrillator), Intravenous drug users.
Staphylococcus epidermidis - Prosthetic valves, Intravascular catheters, Implanted devices
Viridans group streptococci - 👄Gingival manipulation, Respiratory tract incision or biopsy
Streptococcus gallolyticus (S bovis) - Colon carcinoma 🦀, Inflammatory bowel disease 💩
Enterococci - Nosocomial urinary tract infections (UTI) 🚽
Fungi (eg, Candida species) - Immunocompromised host, Intravascular catheters, Prolonged antibiotic therapy
Positive serologic test or single positive blood culture for Coxiella burnetii (Q fever) and for Bartonella, Legionella, Brucella, Mycoplasma, and Chlamydophila.
Additional causes of culture-negative endocarditis include a group of gram-negative pathogens constituting the HACEK group: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella species, nutritionally variant streptococci (eg, Abiotrophiaspecies, Trophermyma whippelii), and fungi (eg, Aspergillus species, Histoplasma capsulatum).
- Evidence of endocardial involvement (either of the following):
Transthoracic echocardiogram (TTE):oscillating intracardiac mass, abscess, or new partial dehiscence of a prosthetic valve(vegetation). *Transesophageal echocardiography (TEE) is the[initial test of choice]when there is a moderate or high pretest probability of endocarditis (eg, in patients with staphylococcal bacteremia or fungemia, a prosthetic heart valve, or an intracardiac device).TEE is the initial imaging test in some clinical situations, such as detection of left atrial thrombus, evaluation of prosthetic mitral valve dysfunction, and evaluation of suspected aortic dissection, as well as in patients with a moderate to high pretest probability of endocarditis.
Physical examination: new valve regurgitation (change in pre-existing murmur is not sufficient). The vegetations of IE usually cause regurgitant murmurs.
DUKE MINOR Criteria:
- Predisposing heart condition (RF, IVDA, endo, prosthetics) or 💉injection drug user
- Fever: Body temperature >38.0°C (100.4°F)
- Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, or Janeway lesions
- Immunologic phenomena (Rheumatologic): glomerulonephritis, Osler nodes, Roth spots, positive rheumatoid factor
- Microbiologic: serologic evidence of infection or positive blood cultures not meeting the major criteria (a single blood culture for coagulase-negative staphylococci is not sufficient)
Rx: Consider antibiotic prophylaxis only in patients with: High-risk cardiac conditions include the presence of a prosthetic cardiac valve, unrepaired cyanotic congenital heart disease, congenital heart disease repair with prosthetic material or device within the last 6 months, presence of palliative shunts and conduits, cardiac valvulopathy in cardiac transplant recipients, and a history of infective endocarditis. High-risk surgical procedures include dental procedures involving manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa as well as respiratory tract procedures that involve perforation of the respiratory mucosa (tonsillectomy, adenoidectomy).
Amoxicillin and cephalosporins, such as cephalexin, are frequently prescribed. Clindamycin, azithromycin, or clarithromycin are appropriate alternatives in patients with penicillin allergy.
Tx: Empiric therapy for early prosthetic valve infective endocarditis includes vancomycin, gentamicin, and rifampin for multidrug-resistant bacteria, particularly coagulase-negative staphylococci.
The Infectious Diseases Society of America Clinical has practice guidelines that recommend intravenous vancomycin (or daptomycin) for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infective endocarditis. The recommended duration of treatment for S. aureus-associated native valve infective endocarditis is 6 weeks.
Klebsiella pneumonia
8–72 h
Laryngitis
Laryngitis with pharyngitis is generally associated with a viral infection.
Tx: Supportive care
Legionella Pneumonia
Hx: Suspect in patients with risk factors (eg, age ≥50 years, smoking history, immunocompromising condition) who present with severe pneumonia and extrapulmonary symptoms (eg, headache, confusion, diarrhea, kidney failure).
Dx: Hyponatremia (< 136mEq/L); The urine antigen test detects only Legionella serogroup 1.
◼ SPIROCHETES
Lyme disease
A few weeks after a camping trip and presumptive exposure to the Ixodes tick.
Stage 1: Early localized (days–1 month)
- Rash (Erythema migrans)
- Fatigue, headache
- Myalgias, arthralgias
Stage 2: Early disseminated (weeks–months)
- Multiple erythema migrans
- Unilateral/bilateral CN palsy (eg, CN VII)[facial]
- Meningitis
- 💗Carditis (eg, AV block)
- 🗺 Migratory arthralgias 💥
Facial nerve palsy is one of the more common signs; it may be unilateral or bilateral.
Stage 3: Late (months–years)
- Arthritis
- Encephalitis
- Peripheral neuropathy
Synovial fluid shows an inflammatory profile with an average leukocyte count of 25,000/mm3; Gram stain and culture are usually negative, although polymerase chain reaction (done for investigative purposes) may demonstrate B burgdorferi DNA.The diagnosis can be confirmed with serum ELISA and Western blot testing.
Occurs months to years later and is characterized by recurrent and sometimes destructive oligoarticular arthritis.
The causative agent is the spirochete Borrelia burgdorferi, which is spread to humans by the bite of an infected Ixodes tick. Diagnosis of early localized Lyme disease is based solely on the presence of the trademark rash in the context of recent travel to Lyme-endemic areas.
Tx: Clinical trials have shown that oral doxycycline, amoxicillin, and cefuroxime have equivalent efficacy for treating early localized Lyme disease.
👶🏽 Doxycycline should preferably be avoided in children age <8 years and pregnant women. It can slow bone growth in exposed fetuses and, in young children, is associated with risk of enamel hypoplasia and permanent teeth stains during tooth development (although the risk is likely small with a short course of doxycycline). Therefore, oral amoxicillin or cefuroxime is the treatment of choice for children age <8 years and pregnant women.
🌑 Syphilis
Primary syphilis: patients present with a painless ulcer (eg, chancre) with a clean base and raised indurated edges as well as painless regional lymphadenopathy.
Secondary syphilis: typically occurs weeks to months after the onset of primary disease and is characterized by a generalized mucocutaneous rash that involves the palms and soles, generalized lymphadenopathy, and constitutional symptoms. Inflammation may develop in other organs, resulting in hepatitis, glomerulonephritis, aseptic meningitis, patchy alopecia, and mucous patches. The hypertrophic, wartlike lesions around the anal area, called condyloma lata, are specific for secondary syphilis.
Dx: primary and secondary-stage mucocutaneous lesions can be established by darkfield microscopy visualization of motile Treponema pallidum in exudative fluid from the lesions. In a patient with suggestive clinical findings, a presumptive diagnosis can be based on reactive syphilis serology, which entails the use of a nontreponemal serologic test (eg, rapid plasma reagin [RPR] or VDRL test) followed by a more specific treponemal serologic test (eg, fluorescent treponemal antibody absorption test or T. pallidum particle agglutination assay ). Treponemal serologies typically remain positive for life, whereas nontreponemal serology titers regress after appropriate treatment and are used to assess disease activity.
Tertiary syphilis, which occurs years to decades after the initial infection, is characterized by neurologic findings (eg, meningitis, tabes dorsalis, Argyll Robertson pupil, mental status changes), cardiac abnormalities (eg, thoracic aortic aneurysm), or gummatous disease.
Latent syphilis is characterized by positive serology without symptoms.
Patients with neurosyphilis require cerebrospinal fluid examination for diagnosis (LP).
Late Latent:
Tx: Penicillin G benzathine 7.2 MU total, given as three doses of 2.4 MU IM at 1-wk intervals
❗ Patients with severe penicillin allergies should recieve doxycycline.
Desensitization is costly and time consuming and reserved primarily for situations in which alternate treatments are either ineffective (eg, central nervous system syphilis, multiple treatment failures) or contraindicated (eg, pregnancy).
🌑 Syphilis / Chancroid / LGV
Incubation: 9-90 d.
Primary lesion: papule Dx: Darkfield
Number of lesions: usually one.
Pain: none
Size of lesion: 5-15 mm.
Edges: indurated.
Base: clean.
Depth: moderate.
Lymph nodes: enlarged, nontender.
U.S. epidemiology: Southeast, urban areas.
Secondary: Fever, targetoid rash on palms and soles Dx: RPR -> FTA-Abs
Early Latent
Late Latent
Tertiary: Neurosyphilis (Tabes dorsalis, argyll-robertson) Dx: LP -> CSF-RPR -> CSF FTA-Abs
Painless genital ulcer and bilateral inguinal lymphadenopathy. Initial syphilis screening serology with rapid plasma reagin (RPR). Two types of serologic tests are used in combination to diagnose syphilis:
- Nontreponemal (eg, RPR, VDRL)
- Treponemal (eg, fluorescent treponemal antibody absorption)
Although either type may be used to screen for syphilis, nontreponemal tests may have higher false-negative rates (20%-30%) in patients with primary syphilis.
Patients with negative screening serology and strong clinical evidence of primary syphilis (eg, chancre) should be treated empirically with intramuscular benzathine penicillin G as this reduces the risk of transmission. In these patients, repeat nontreponemal serology should be done in 2-4 weeks to establish baseline titers; a 4-fold titer decrease at 6-12 months would confirm adequate treatment.
Primary syphilis
Syphilitic chancres form at the site of direct inoculation with Treponema pallidum. After exposure (3-60 days), patients develop a single papule that turns into a shallow, painless, nonexudative ulcer with indurated edges. Chancres are exceedingly infectious, with rates of T pallidum transmission as high as 30%. Most chancres resolve spontaneously in 6-8 weeks (if untreated), but the systemic spread of T pallidum results in continued infection.
Secondary syphilis: typically occurs weeks to months after the onset of primary disease and is characterized by a generalized mucocutaneous rash that involves the palms and soles, generalized lymphadenopathy, and constitutional symptoms. Inflammation may develop in other organs, resulting in hepatitis, glomerulonephritis, aseptic meningitis, patchy alopecia, and mucous patches.
Dx: primary and secondary-stage mucocutaneous lesions can be established by darkfield microscopy visualization of motile Treponema pallidum in exudative fluid from the lesions. In a patient with suggestive clinical findings, a presumptive diagnosis can be based on reactive syphilis serology, which entails the use of a nontreponemal serologic test (eg, rapid plasma reagin [RPR] or VDRL test) followed by a more specific treponemal serologic test (eg, fluorescent treponemal antibody absorption test or T. pallidum particle agglutination assay ). Treponemal serologies typically remain positive for life, whereas nontreponemal serology titers regress after appropriate treatment and are used to assess disease activity.
Tertiary syphilis, which occurs years to decades after the initial infection, is characterized by neurologic findings (eg, meningitis, tabes dorsalis, Argyll Robertson pupil, mental status changes), cardiac abnormalities (eg, thoracic aortic aneurysm), or 🌑 gummatous disease.
Latent syphilis is characterized by positive serology without symptoms.
Patients with neurosyphilis require cerebrospinal fluid examination for diagnosis (LP). Tx: Aqueous crystalline penicillin G 18-24 MU/d, given as 3-4 MU IV every 4 h or continuous infusion, for 10-14 d
Ddx:
Granuloma inguinale is caused by Klebsiella granulomatis and is marked by the formation of extensive, progressive, and painless genital ulcers, usually without lymphadenopathy. Granuloma inguinale is seen primarily in India, Guyana, and New Guinea. In the United States, <100 infections occur annually, most in patients who have traveled to these countries. Donovan bodies are present in these patients.
Granuloma inguinale (Donovanosis) is extremely rare in the United States. Ulcers most commonly are large, nontender, and beefy red and bleed easily when touched. The lesions differ from the syphilitic chancre in that they are larger, may be multiple in number, and usually have a very beefy red base. The ulcers do not heal spontaneously and can be present chronically.
Chancroid, caused by Haemophilus ducreyi, is most commonly found in developing regions but is rare in the United States and produces a painful, tender ulceration of the vulva. Chancroid is successfully treated with either azithromycin or ceftriaxone.
Incubation: 1-14 d. Primary lesion: pustule. Number of lesions: one or many.
Pain: exquisite. Size of lesion: 5-25 mm. Edges: ragged, undermined. Base: friable, purulent exudate. Depth: deep, excavated.
Lymph nodes: tender, may suppurate/form buboes.
U.S. epidemiology: rare, occasionally seen in warmer climates (many of these cases are imported from Mexico or the Caribbean).
Lymphogranuloma venereum (LGV) is a chronic infection produced by C. trachomatis. It is most commonly found in the tropics. The primary infection begins as a painless ulcer on the labia or vaginal vestibule; the patient usually consults the physician several weeks after the development of painful adenopathy in the inguinal and perirectal areas. Diagnosis can be established by culture or by demonstrating the presence of serum antibodies to C. trachomatis. Therapy for both granuloma inguinale and LGV is administration of 🎡tetracycline.
LGV is extremely rare in the U.S. The infection can begin as a small papule, erosion, or ulcer in the genital or perineal region; the lesion usually is asymptomatic and heals quickly without scarring. Patients with LGV rarely, if ever, present in this early ulcerative stage. Subsequently, patients develop the painful lymphadenopathy and buboes. During this stage, patients may have fever and other constitutional symptoms and develop draining fistulae. The early ulcerative lesions of LGV differ from those of primary syphilis in that they are smaller and less destructive and heal promptly. Dx: NAAT Tx: Doxy
Babesiosis
Babesiosis is a tick-borne protozoal illness endemic to the northeastern United States. Human transmission occurs via Ixodes scapularis approximately 48-72 hours after attachment. I scapularis also may transmit Borrelia burgdorferi (Lyme disease) and Anaplasma phagocytophilum (human granulocytic anaplasmosis); therefore, coinfection with multiple organisms is possible. Peak prevalence is in July and August, when tick populations are at their highest.
Infection is often asymptomatic or mild, but patients with immunocompromise, age >50, or a history of splenectomy are at higher risk for severe illness. Symptoms typically include the gradual onset of fatigue, malaise, weakness, chills, and fever. The organism multiplies in red blood cells, so patients may develop anemia with signs of intravascular hemolysis (jaundice, dark urine, indirect hyperbilirubinemia, reticulocytosis, elevations of aminotransferases and lactate dehydrogenase). Thrombocytopenia is common and mild hepatosplenomegaly may occur. Diagnosis is made by identifying organisms on peripheral blood smear (“Maltese cross”). Treatment includes 7-10 days of atovaquone plus azithromycin or quinine plus clindamycin (for severe illness). Symptoms may take up to 3 months to fully resolve.
🌴 Tabes dorsalis
Epidemiology
- Increased incidence of syphilis in men who have sex with men & HIV-infected patients
- HIV-positive patients develop neurosyphilis more rapidly
Pathogenesis
- Treponema pallidum spirochetes directly damage the dorsal sensory roots
- Secondary degeneration of the dorsal columns
Clinical findings
- Sensory ataxia
- Lancinating pains
- Neurogenic urinary incontinence
- Associated with Argyll Robertson pupils
Tabes dorsalis is a neurodegenerative condition that involves the posterior spinal columns and nerve roots. Posterior column involvement results in impaired vibration/proprioception, sensory ataxia, and instability during the Romberg test. Nerve root involvement can contribute to diminished pain/temperature sensation and reduced/absent deep tendon reflexes. Patients might complain of lancinating pains, described as brief shooting or burning pain in the face, back, or extremities. Tabes dorsalis can also be associated with Argyll Robertson pupils, which are typically miotic and irregular and characterized by normal pupillary constriction with accommodation but not with light.
The treatment of choice for neurosyphilis is intravenous (IV) penicillin for 10-14 days due to its adequate cerebrospinal fluid penetration and efficacy.
Leptospirosis
A spirochetal disease that has two phases. The bacteremic phase is characterized by sudden onset fevers, rigors, headache, photophobia, and severe myalgias. Four to 30 days
later, the immunologic phase ensues and is characterized by conjunctivitis, photophobia, retrobulbar pain, neck stiffness, diffuse lymphadenopathy, hepatosplenomegaly, and
aseptic meningitis. The most severe form is called Weil disease; it is associated with up to 40% mortality and is characterized by high direct bilirubin and mild elevation in
alkaline phosphatase and transaminase values, combined with a high creatine phosphokinase.
Leprosy
Leprosy is a chronic granulomatous disease of the skin and peripheral nerves caused by the acid-fast bacillus Mycobacterium leprae. Transmission is thought to occur via respiratory droplets, although cases are occasionally linked to close contact with a nine-banded armadillo. Infections are rare in the United States and occur primarily in immigrants or travelers to endemic regions (eg, Asia, Africa, South America).
Manifestations include >1 chronic, anesthetic, macular (often hypopigmented) ⚪ skin lesions with raised, well-demarcated borders. Nearby nerves often become nodular and tender, and segmental demyelination may result in loss of sensation and motor function. Diagnosis is clinical in endemic regions, but in the United States patients usually require a full-thickness biopsy of the skin lesion edge (as M leprae is not culturable).
Patients with minimal lesions (“paucibacillary”) are treated with dapsone and rifampin; those with extensive lesions (“multibacillary”) require the addition of clofazimine. Lesions often take months or years to heal completely.
Lung abscess
Frequently involves the posterior upper segments of the upper lobes; may be acute or indolent; causes indolent symptoms of fever, cough, dyspnea, weight loss and CT scan findings of an infiltrate with a cavity.
- *Hx:** Patients usually have foul-smelling sputum.
- *Dx:** Usually have necrotic tissue with air fluid levels
Malaria
A protozoal disease caused by Plasmodium (red blood cell [RBC] parasite transmitted by Anopheles mosquitoes). The hallmark is cyclical fever, coinciding with Plasmodium-induced RBC lysis.
Patients present with influenza-like symptoms, jaundice, and in its most severe forms with obtundation and confusion.
Fever in the setting of malaria is often intermittent. The diagnosis of malaria is established by visualization of parasites on peripheral smear.
The typical cycle (uncommon) consists of a cold phase (chills, shivering), then a hot phase (high-grade fevers), then a sweating stage (diaphoresis, fever resolution). Headache, malaise, myalgias, vomiting, and diarrhea are often seen. Anemia andthrombocytopenia are classic. Blood smears are the diagnostic gold standard.
Prophylaxis: Should begin 2 days to 2 weeks before departure in order to have adequate levels of drug on arrival and to identify potential side effects before leaving.
Whether or not to use drugs such as atovaquone-proguanil, mefloquine, or primaquine for resistant P falciparum will depend on knowledge of specific local patterns of drug sensitivity of plasmodia.
Tx: Long-sleeved clothing, insect repellent, and insecticide-treated bed nets can be somewhat protective; however, most returning travelers who have malaria did not adhere to chemoprophylaxis. Treatment regimens depend on the species and severity of infection.
Malignant Hyperthermia
Malignant hyperthermia is an inherited skeletal muscle disorder characterized by a hypermetabolic state precipitated by exposure to volatile inhalation anesthetics (eg, halothane, isoflurane, enflurane, desflurane, sevoflurane) and depolarizing muscle relaxants (eg, succinylcholine, decamethonium). Malignant hyperthermia usually occurs on exposure to the drug. Increased intracellular calcium leads to sustained muscle contractions, with resultant skeletal muscle rigidity and masseter spasm, tachycardia, hypercarbia, hypertension, hyperthermia, tachypnea, and cardiac arrhythmias. Rhabdomyolysis and acute kidney failure can develop. Malignant hyperthermia is life threatening if not treated immediately.
Tx: Includes discontinuing the offending drug and providing supportive care (eg, hydration, oxygen, cooling measures). Dantrolene sodium, a skeletal muscle relaxant, is the treatment of choice.
Meningococcal infection
Meningococcal infection may be associated with meningitis and hemorrhagic rash. The diagnosis is established based on cerebrospinal fluid examination.
Metastatic malignancy to the bone
Usually associated with a primary lesion (eg, breast, prostate, lung). Metastasis is usually multifocal and tends to remain isolated to one vertebral body, whereas osteomyelitis often crosses the end plate.
⛑ MENINGITIS
<1 month
- Group B Streptococcus
- Escherichia coli & other gram-negative bacteria
- Listeria monocytogenes
- Herpes simplex virus
≥1 month
- Streptococcus pneumoniae
- Neisseria meningitidis
N meningitidis is the second most common cause of bacterial meningitis in children age 1 month to 10 years (behind Streptococcus pneumoniae) and is the most common cause among adolescents. The risk of acquiring meningococcal disease is 10-fold higher in children age <2 years compared with older children.
Dx:
- Protein concentration [normal <40 mg/dL]
- Glucose concentration [normal 40 - 70 mg/dL]
- Leukocyte (WBC) count [normal 0 - 5 cells/mm3]
