Infectious Disease Flashcards
Clinical clues for Legionella Pneumonia
- Recent travel (especially cruise or hotel stay) within the previous 2 weeks
- Contaminated potable water in hospitals/nursing homes
- Fever > 102.2
- Bradycardia relative to high fever
- Neurological symptoms (especially confusion)
- GI symptoms (especially diarrhea)
- Unresonsive to beta-lactam and aminoglycoside antibx
Laboratory clues for legionella pneumonia
- Hyponatremia
- Heptatic dysfunction
- Hematuria and proteinuria
- Sputum Gram stain showing many neurtrophils but few or no microorganisms
Most common method used to confirm diagnosis of Legionnaires’ disease
urine antigen testing
When Legionnaires’ dz is suspected or proven, what therapy should be started
-Macrolide or fluoroquinolone
Describe the CSF findings in Cryptococcal meningoencephalitis
- High opening pressure (normal: 100-180 mm H20)
- Low glucose, High protein
- WBC < 50/uL with mononuclear predominance
- Transparent capsule seen with india ink stain
- Cryptococcal antigen positive
- Culture on Sabouraud agar
Describe the treatment of Cryptococcal meningoencephalitis?
- Initial: Amphotericin B with Flycytosine
- Maintenance: Fluconazole
Cryptococcal meningoencephalitis is typically seen in immunocompromised patients, especially those with advance HIV disease at what CD4 count
< 100
This is used to treat dermatophytosis and onychomycosis?
Griseofulvin
Patient with thrush and an opportunistic infection such as Cryptococcus suggest that the patient is immunocompromised. HIV is a common and treatable cause of immunosuppression in this patients age group. Describe the testing and treatment of the HIV in the setting of acute infection?
- She should be tested for HIV, but initiation of antiretroviral therapy in the setting of acute infection is not recommended due to risk of immune reconstitution syndrome
- Antiretroviral therapy should be deferred until at least 2-8 weeks after completing induction antifungal therapy for crytpococal meningitis (this was just specific for this infection)
Describe the use of Itraconazole in treating Cryptococcal infection
- Can be used as on alternate to fluconazole in the treatment of pulmonary cryptococcal infection.
- However, it does not cross the BBB, making it ineffective in CNS infection
This is used in the treatment of cerebral toxoplasmosis, which typically presents with headache, focal neurologic deficits, and/or seizures. Neuroimaging shows multiple ring-enhancing lesions with edema
Sulfadiazine-pyrimethamine
Manifestation of Primary syphilis?
-Painless genital ulcer (chancre)
Manifestation of Secondary Syphilis?
- Diffuse rash (palms and soles)
- Lymphadenopathy (Epitrochlear**)
- Condyloma lata
- Oral lesions **
- Hepatitis
Manifestation of Latent syphilis
Asymptomatic
Manifesation of Tertiary Syphilis
- CNS (Tabes Dorsalis, Dementia)
- Cardiovascular (Aortic aneursym/insufficiency)
- Cutaneous (gummas)
Describe the oral mucosa lesions in secondary syphilis?
-grey mucous patches
Describe the rash seen in secondary syphilis
A diffuse maculopapular rash that begins on the trunk, extends to the extremities, and involves the palms and soles
The presence of EPITROCHLEAR lymphadenopathy is particularly pathognomonic for what?
secondary syphilis
Describe the diagnosis and treatment of syphilis
- Diagnosed using a combo of nontreponemal (eg, RPR) and treponemal-specific (eg, T pallidum enzyme immnoassay) serologic tests.
- Treatment for secondary syphilis is the same as for primary syphilis - one dose of IM penicillin G benzathine - which provides up to 3 weeks of treatment-dose penicillin.
- Adequate treatment is confirmed by a 4-fold decrease in serologic titers at 6-12 months
Patients who receive solid organ transplantation require high-dose immunosuppressant meds to prevent rejection. This creates an immunocompromised state that puts patients at high risk for opportunistic infections, most notable Pneumocystis pneumonia (PCP) and CMV. Post-transplant patients with PCP typically have acute respiratory failure (tachypnea, hypoxia), dry cough, and fever (the course is more indolent in patients with HIV). Lactate dehydrogenase levels are often elevated, and chest x-ray classically reveals bilateral, diffuse interstitial infiltrates. Describe how you yield this diagnosis
- P jirovecii (The causative organism of PCP) cannot be cultured
- Diagnosis requires the examination of respiratory samples using microscopy with specialized stains
- Induced sputum is the least invasive method for obtaining an adequate respiratory samples.
- If this does not yield a diagnosis, bronchoscopy with bronchoalveolar lavage*** is required
Beta-D-glucan is part of the cell wall of fungi; therefore, a serum assay can be useful in the diagnosis of many fungal infection. Particularly which ones?
- Aspergillus
- Candida
What organism?
- AIDS with CD4 < 180
- Severe, watery diarrhea **
- Low-grade fever
- Weight loss
Cryptosporidium
What organism?
- AIDS with CD4 < 100
- Watery diarrhea
- Crampy abdominal pain
- Weight loss
- Fever is RARE**
Microsporidium/isosporidium
What organism?
- AIDS with CD4 < 50
- Watery diarrhea
- HIGH FEVER (> 102.2)
- Weight loss
Mycobacterium avium complex
What organism?
- AIDS with CD4 < 50
- Frequent, small volume diarrhea
- Hematochezia
- Abdominal pain
- Low-grade fever
- Weight loss
CMV
Cryptosporidium is among the most common causes of infectious diarrhea worldwide and is commonly spread how?
- Through drinking water
- Animal contact (eg, horse breeding)
- Person-to-person contact
What does stool examination show is cryptosporidium infection and what is treatment (especially in AIDS)
- Stool examination with modified acid-fast stain reveals cryptosporidial oocytes measuring 4-6 um
- The mainstay of treatment is supportive care and antiretroviral therapy because infection often persists until CD4 counts improve
How does Entamoeba histolytica infection present?
Dysentery, which is characterized by abdominal pain, diarrhea, and bloody stools
Strongyloides stercoralis infxn is associated with what presentation?
- Cutaneous (pruritus and urticaria)
- Pulmonary
- GI
Acute Pyelonephritis can result in Gram-negative sepsis. Urine (and blood) cultures should be obtained routinely before administration of empiric antibiotics. When is urological imaging (eg, CT of abdomen/pelvis) indicated?
- typically reserved for patients with persistent clinical symptoms despite 48-72 hours of therapy
- History of nephrolithiasis
- complicated pyelonephritis (abscess, multiorgan failure, shock, renal failure, MOre likely in DM, kidney stones, immunosuppression, or anatomic abnormalities)
- Unusual urinary findings (eg, gross hematuria, suspician for urinary obstruction)
Pathogenesis of C. Diff colitis
- Disruption of intestinal flora –> C difficile overgrowth
- Exotoxins cause mucosal inflammation/injury
Most common clinical presentation of C. diff colitis?
-WATERY diarrhea
Diagnosis and treatment of C. diff colitis
- Stool PCR (stool toxin testing)
- ORAL Vancomycin or metronidazole
Stool cultures are NOT highly diagnostic in patients who develop diarrhea after >72 hours of hospitalization. They can be helpful in what situations?
- Immunocompromised patients
- Those with bloody diarrhea or underlying IBD to distinguish between disease flare and infection
Nonspecific systemic symtptoms (eg, fever, cough, abdominal pain, diarrhea, night sweats, weight loss) in the presence of SPLENOMEGALY and an elevated ALK PHOS level should raise suspicion for what in patients with HIV and a CD4 count < 50?
- Disseminated Mycobacterium avium complex (MAC)
- The splenomegaly and alk phos reflect MAC hepatosplenic involvement
Diagnosis, Treatment and Prophylaxis of MAC infection in HIV patients?
- Diagnosis: blood cultures (or lymph node or bone marrow biopsy)
- Treatment: first line is clarithromycin or azithromycin
- Patients with CD4 count < 50 should receive Azithromycin prophylaxis against MAC
Prophylaxis of Pneumocystis pneumonia in HIV
- Trimethoprim-sulfamethoxazole is preferred
- Dapsone is alternate
This can be considered as prophylaxis in patients with HIV who have had episodes of esophageal candidiasis?
Fluconazole
What organism?
- Gram-negative, free-living in MARINE environments
- Ingestion (oysters) or wound infection
- Increased risk in those with LIVER disease ** (cirrhosis, hepatitis, hemochromatosis)
Vibrio Vulnificus
Describe the manifestations of Vibrio Vulnificus infection
- Rapidly progressive (often < 12 hours)
- Septiciemia (septic shock, BULLOUS lesions)
- Cellulitis: HEMORRHAGIC BULLAE, necrotizing fasciitis
Why are those with hemochromatosis at particularly great risk of getting Vibrio vulnificus infection?
free iron act as an exponential growth catalyst
Describe diagnosis and treatment of Vibrio vulnificus infection
- Diagnosis is made by blood and wound cultures
- Treatment (IV antibiotics) should NOT BE DELAYED due to high risk of DEATH
Describe how you diagnose CMV colitis in HIV patient with CD4 < 50
- The diagnostic test of choice is a colonoscopy with biopsy (eosinophilic intranuclear and basophilic intracytoplasmic inclusions)
- Serology and PCR results may be positive but do NOT conclusively prove end-organ disease (eg, colitis)
What is the most likely diagnosis in a patient from Mississippi who was initially thought to have sarcoidosis (cough, hilar adenopathy, erythema nodosum, and non-caseating granulomas in an African American individual) but deteriorates following high-dose corticosteroid therapy
Histoplasmosis
What is used for diagnosis of Histoplasmosis
-Careful fungal tissue stains and culture, along with Histoplasma urinary antigen testing
Blastomyces (associated with contact with soil or rotting wood, with dissemination in immunocompromised hosts presenting as skin lesions, osteolytic bone lesions, or prostate involvement) is also present in Mississippi and should be excluded in a patient with suspected histoplasmosis. What symptom is more suggestive of histoplasmosis?
Hilar adenopathy
Where is coccidioides found
SOUTHWESTERN US
Postherpetic neuralgia is persistent neuritic pain > 4 months after Herpes Zoster rash onset. What is treatment?
-TCAs, Pregabalin, Gabapentin
This is used in the treatment of drug-resistant CMV. It can also be considered for patients with severe VZV who fail first line drugs
Foscarnet
Doxycycline is an excellent treatment option for lyme disease as it has the advantage of simultaneously preventing or treating coexisting what?
human granulocytic anaplasmosis, an infection also carried by I. scapularis
Ludwig angina is a rapidly progressive cellulitis of the submandibular space. Most cases arise from what?
-Dental infections in the mandibular molars that spread contiguously down the root into the submylohyoid (and then sublingual) space
Describe how someone with Ludwig angina presents
- develops symptoms rapidly with systemic (fever, chills, malaise) and local compressive (eg, mouth pain, drooling, dysphagia, muffled voice, airway compromise) manifestations
- Physical exam findings are often striking due to mass effect from edema
- The submandibular area is usually tender and indurated, and the floor of the mouth is often elevated, displacing the tongue
- Anaerobic, gas-producing bacteria may cause crepitus
Diagnosis and treatment of Ludwig angina
- CT scan of the neck confirms the diagnosis and rules out an abscess
- Most patients are treated with IV antibiotics (eg, ampicillin-sulbactam, clindamycin) and removal of the inciting tooth
- Drainage and surgery are rarely required as the process is cellulitic and typically nonsuppurative
- Impaired respiratory status requires prompt attention and early intervention with a mechanical airway
Lymph nodes can rarely cause an airway obstruction in Tuberculosis lymphadenitis . .what is this called?
Scrofula
Describe the use of serology in the diagnosis of Lyme disease
- Serology is NOT recommended in early localized disease as it is too insensitive and many patientss would be seronegative
- After the onset of erythema migrans, IgM antibodies to B burgdorferi usually appear within 1-2 week, and IgG antibodies typically appear within 2-6 weeks
- However, serology should be performed in patients with signs of early disseminated or late Lyme disease
HIV-associated diarrhea has many potential causes. CD4 count, chronicity, and the presence or absence of symptoms of colitis help narrow the differential diagnoses. Workup typically begin how?
-sending the stool for several tests including culture, ova and parasites, acid-fast stain, and C diff. antigen
Patients with pneumonia caused by anaerobic organisms typically present with indolent symptoms such as fever, malaise, and a characteristic foul-smelling sputum. Poor dentition, which predisposes to a greater quantity of oral anaerobic organisms, increases risk for anaerobic aspiration pnemonia. Other risk factors for aspiration include forms of upper airway instrumentation (eg, endotracheal or nasogastric tubes), GERD, dysphagia, and impaired consciousness . . describe the antibiotic manageent
- Clindamycin
- Metronidazole with amoxicillin
- Amoxicillin-Clavulonate
- Carbapenem
Describe the epidemiology of Acute epididymitis?
- Age <35: Sexually transmitted (chlamydia, gonorrhea)
- Age > 35: Bladder outlet obstruction (coliform bacteria)
- Unilateral testicular pain
- Epidiymal edema
- Dysuria, frequency (with coliform infection)
Acute Epididymitis
Describe the likely causative organism of Acute Epididymitis based on Age
- Those Age > 35: Ascending coliform bacteria such as E. coli are most likely and urinary tract inflammatory symptoms (eg, dysuria, frequency are common)
- Patients age < 35: Chlamydia, N. gonorrhoeae
Describe the treatment of Acute Epididymitis
- Ceftriaxone/Doxycycline (if STI)
- Levofloxacin (if coliform bacteria)
Staph aureus can cause epidiymitis or orchitis in what setting?
-In the setting of a surgical procedure or severe overlying skin infections but is otherwise unlikely
This usually presents with the classic triad of fever, leukocytosis, and left upper-quadrant abdominal pain. Patients can also develop left-sided pleuritic chest pain, left pleural effusion, and splenomegaly
Splenic abscess
What are the risk factors for splenic abscess
- Infection (eg, infective endocarditis) with hematogenous spread
- Immunosuppression
- IV drug use
- Trauma
- Hemoglobinopathies
Treatment of splenic abscess
- Combination of broad-spectrum antibiotics and splenectomy
- Possible percutaneous drainage in poor surgical candidates
A patient with elevated transaminases, hepatomegaly and a positive serology test for hepatitis C virus (HCV) antibody (suggesting likely exposure to HCV) should undergo testing to confirm the diagnosis of chronic HCV infection. Describe this diagnostic process
-Because the virus may spontaneously clear in up to hald of affected patients, Diagnosis of chronic infection is a 2-step process that require both a positive serologic test for the HCV antibody and a confirmatory molecular test for the presence of circulating HCV RNA
In patients with esablished HCV, what imaging surveillance is needed and why?
-Abdominal U/S repeated every few months is recommended forsurveillance for hepatocellular carcinoma
This is an uncommon inflammatory disorder characterized by recurrent high fevers, arthritis/arthralgias, and a salmon-colored macular or maculopapular rash. ESR may be markedly elevated
Adult Still disease
Describe the manifestation of the immunologic phenomena that comes from infective endocarditis
- Positive Rheumatoid factor (possibly due to antibody production)
- Immune complex-mediated glomerulonephritis (hematuria, red cell casts)
- Cutaneous manifestations: Osler nodes (painful fingertip nodules)
What do lab studies usually show in infective endocarditis
- normocytic anemia
- dramatic elevations in ESR
Describe the clinical features of Mycoplasma pneumonia
- Indolent headache, malaise, fever, persistent dry cough
- Pharyngitis (NONexudative)
- Macular/vesicular rash **
diagnostic findings in mycoplasma pneumonia
- Normal leukocyte count
- Subclinical hemolytic anemia (cold agglutinins)
- Interstitial infiltrate (chest x-ray)
- A serous pleural effusion may be present in approximately 25% of patients
Risk factors for Neisseria gonorrhoeae infection are shared with many other STIs and include age <25, new or multiple sexual partners, substance abuse, and men who have sex with men. Coinfection with multiple pathogens is common; rates of simultaneous gonococcal and Chlamydia trachomatis infection are as high as 40% (Azithromycin also treats chlamydia). What other pathogens should a patient with gonorrhoaea be screens for?
- HIV
- Syphilis
- Hep B
Most common cause of community-acquired bacterial meningitis?
- Strep pneumo
- is usually secondary to hematongenous dissemination and may occur with or without concurrent pneumococcal pneumonia
Individual with a history of high risk sexual intercourse should be screened for HIV and hepatitis B. Who should be screened for hepatitis C?
- IV drugs users
- those with high risk needlestick exposure
- those who received blood transfusion before 1992
This is primarily seen in patients with HIV with CD4 counts <100. Symptoms feature vascular cutaneous lesion that often begin as small reddish/purple papules that evolve into friable pedunculated or nodular lesions. constitutional symptoms (eg, fever, malaise, night sweats) are typically present and organ (Liver, CNS, bone) involvement may occur.
Bacillary angiomatosis (Bartonella)
Treatment of bacillary angiomatosis
- Antibiotics (doxy, erythromycin)
- initiation of antiretroviral therapy (usually 2-4 weeks later)