brainscape2 Flashcards
Ascariasis
present with intestinal symptoms and eosinophilia, but more often has a lung phase with nonproductive cough followed by an asymptomatic intestinal phase.? Ascariasis can also present with the worms obstructing the small bowel or bile ducts.
Brown recluse spider
the upper arm, thorax, or inner thighs.? Bites are characterized by a red plaque or papule with central clearing; some patients develop a necrotic eschar.
Infective endocarditis
fever, cardiac murmur, and embolic phenomenon (eg, subungual splinter hemorrhages).? Although this patient’s drug abuse history can suggest endocarditis,
Kaposi sarcoma
This patient with a history of injection drug use presents with clusters of violaceous skin papules indicating likely Kaposi sarcoma (KS), an AIDS-defining illness.? KS is an endothelial malignancy triggered by the reactivation of human herpesvirus 8 (HHV8).
HIV-associated KS is typically marked by the development of papular cutaneous lesions that may become confluent.?
The lesions are violaceous, pink, red, or brown due to an abundance of erythrocytes within the tumor vasculature and tissue.? Pruritus, pain, and skin necrosis are rare.? Obstruction of draining lymphatic channels can cause distal lymphedema (eg, lower extremity swelling).? Visceral lesions in the lungs and gastrointestinal tract may be life-threatening.
Because the tumor arises due to unchecked HHV8 replication in the setting of profound immunosuppression (eg, low CD4, high viral load), first-line treatment is antiretroviral therapy (ART).?
Streptococcus pneumoniae
HIV are at increased risk for community-acquired pneumonia (CAP), particularly in the setting of advanced disease (CD4 count <200/mm3).? Streptococcus pneumoniae causes the majority of cases, likely due to increased rates of colonization and impaired immunity against encapsulated bacteria.
“Rusty sputum” is classic for pneumococcal pneumonia but may not always be present.?
Pneumococcal vaccination is recommended for all patients with HIV to reduce the risk of invasive S pneumoniae disease.
usually causes respiratory tract infections (eg, pneumonia), meningitis, or bacteremia.
Actinomyces
Actinomyces causes abscesses primarily at the head and neck with characteristic granular yellow pus (“sulfur granules”).? It can also cause indolent pulmonary disease.
Penicillin G is the treatment of choice for Actinomyces, another filamentous gram-positive bacterium.?
Actinomyces is anaerobic, not aerobic; Actinomyces is not acid-fast; and sulfur granules may be found with Actinomyces infection.
Actinomyces is an anaerobic bacterium of the oral cavity that may cause invasive disease in patients with dental infections or trauma (eg, tooth extraction).? Risk of infection is increased in those with poorly functioning immunity due to underlying immunosuppression, diabetes mellitus, or malnutrition.
Patients typically develop a chronic, slow-growing, nontender, indurated mass that eventually forms multiple sinus tracts to the skin.? A pathognomonic feature is the presence of purulent discharge with “sulfur granules”
penicillin
TB resembles Actinomyces on Gram stain, but TB is usually acid-fast (unlike Actinomyces).
acute bacterial meningitis
- This patient’s presentation of fever, headache, nuchal rigidity, vomiting, and altered mental status is consistent with acute bacterial meningitis.? Evaluation of bacterial meningitis includes blood cultures and lumbar puncture (LP).? A head CT scan should be performed prior to LP
Cefepime is a fourth-generation cephalosporin that covers most of the major organisms of bacterial meningitis (eg, Streptococcus pneumoniae, Neisseria meningitidis, group B streptococci, Haemophilus influenzae) as well as Pseudomonas aeruginosa.? Vancomycin provides coverage against cephalosporin-resistant pneumococci, and ampicillin covers Listeria monocytogenes.?
?-Age 2-50: Streptococcus pneumoniae, Neisseria meningitidis
-Age >50: S pneumoniae, N meningitidis, Listeria
-Immunocompromised: S pneumoniae, N meningitidis, Listeria,gram-negative rods
Acute giardiasis
can present with diarrhea (can be steatorrhea), flatulence, abdominal cramps, weight loss, and nausea.
Acute hepatitis A infection
fever, malaise, jaundice, and hepatomegaly, particularly in patients who have recently traveled to developing countries.?
Acute HIV
Acute HIV may cause mononucleosis-like symptoms (eg, fever, fatigue, sore throat, painless lymphadenopathy), a generalized rash, and painful mucocutaneous ulceration (shallow, sharply demarcated, with a white base).?
Mononucleosis-like syndrome?(eg, fever,?lymphadenopathy, sore throat, arthralgias)
Generalized macular rash
Gastrointestinal symptoms
This patient’s subacute gastrointestinal symptoms (eg, diarrhea, nausea, cramps), systemic manifestations (eg, fever, weight loss, night sweats, arthralgias), lymphadenopathy, and transient rash should raise suspicion for acute HIV infection.
Two notable clues (not always present) are painful oral ulcerations and/or oval, pink/red macular lesions
HIV infection often causes a mononucleosis-like syndrome consisting of fever, night sweats, lymphadenopathy, arthralgias, and diarrhea.? Important diagnostic clues include oral ulcerations
Acute HIV infection also causes fever, malaise, and generalized lymphadenopathy, and testing should be performed in this patient.? However, adenopathy in acute HIV is nontender
constitutional symptoms and maculopapular rash on the trunk, neck, and face, not the palms/soles.? Most patients also have diffuse lymphadenopathy, sore throat, and (often) mucocutaneous ulcers.?
Acute lymphoblastic leukemia
present with fever, fatigue, lymphadenopathy, splenomegaly, and lymphocytosis.?
however, bone marrow failure would cause a low, rather than an elevated, reticulocyte count, as in this patient.?
cute lymphoblastic leukemia usually causes lymphadenopathy and symptoms related to anemia (eg, fatigue), thrombocytopenia (eg, bruising), or neutropenia (eg, infection).? Peripheral smear would show blasts
Adenovirus infection
fever, exudative pharyngitis, malaise, and generalized lymphadenopathy
Allergic bronchopulmonary aspergillosis
often manifests with the classic triad of fever, pleuritic chest pain, and hemoptysis.? Imaging usually reveals focal lesions (nodules with or without cavitation).? It is often associated with immunosuppression (eg, HIV with CD4 count <50/mm3).?
causes prolonged cough but usually occurs in those with underlying asthma or cystic fibrosis.? In addition, an elevated eosinophil, not lymphocyte, count is seen
Aspergillosis tends to cause nodules and focal infiltrates on chest x-ray (not bilateral interstitial infiltrates)
? Aspergillus may cause pulmonary disease (upper lobe cavitary disease) in immunocompromised patients, but microscopy would show acid-fast negative hyphae
Voriconazole
Aspiration pneumonia
cavitary infiltrate and is common in those with alcohol/substance use disorder.? Most cases occur in the lower lobes (particularly the right lower lobe)
dyspnea, cough productive of foul-smelling sputum, and fever.?
Babesiosis
This patient visited a Lyme-endemic area and subsequently developed an annular rash with central clearing, the characteristic lesion of early localized Lyme disease.? Although the rash improved with oral doxycycline, she subsequently developed high fever, anemia, and thrombocytopenia, raising strong suspicion for coinfection with Babesia microti.
Lyme disease is transmitted by the Ixodes scapularis tick during blood feeding.? Because this vector also harbors Anaplasma phagocytophilum and B microti, patients with Lyme disease are often (in 4%-28% of cases) coinfected with multiple pathogens.? Doxycycline is effective against A phagocytophilum but has no activity against B microti.
other signs of babesiosis such as anemia, thrombocytopenia, and/or leukopenia are frequently present.? The diagnosis is confirmed when intraerythrocytic parasites are seen on thin peripheral blood smear.? Treatment with azithromycin and atovaquone is curative.
Bartonella henselae (Catscratch disease)
Feline scratch/bite
Flea bite from infected feline
Papule in area of transmission
Prominent, tender regional lymphadenopathy
fastidious, facultative, intracellular, gram-negative coccobacillus.? It is typically transmitted by feline scratch/bite or flea bite.? A papular lesion develops at the site of transmission, and tender regional lymphadenopathy is very prominent.?
catscratch disease is marked by a primary cutaneous lesion (vesicular, erythematous, or papular) at the site of inoculation, patients with this condition have prominent, painful, regional lymphadenopathy,
Bacillary angiomatosis
The organism causes a local dermal infection, spreads to the vascular endothelium, and then attacks red blood cells.? The major manifestations of infection are therefore mostly cutaneous, lymphatic, and endovascular (Cat-scratch disease, bacillary angiomatosis, endocarditis).
Bacillary angiomatosis (BA) is a Bartonella infection seen primarily in patients with HIV with CD4 counts <100/mm3 (CD4-mediated immune response is crucial for control and elimination of the organism).?
Symptoms feature vascular cutaneous lesions that often begin as small reddish/purple papules and evolve into friable pedunculated or nodular lesions.? Constitutional symptoms (eg, fever, malaise, night sweats) are typically present and organ (liver, central nervous system, bone) involvement may occur.
Lesional biopsy with microscopy/histopathology
Doxycycline or erythromycin
Antiretroviral therapy
Beh?et syndrome
A pathergy test diagnoses Beh?et syndrome
Beh?et syndrome can cause recurrent genital ulcers but they are usually small, painful, and on the scrotum.? Oral ulcers are also frequently present.
Blastomycosis
low-grade fever and violaceous skin lesions with scrapings showing yeast,
affects primarily areas in the Midwest and Upper Midwest regions of the United States, extending into the southern Mississippi Valley.
Primary infection occurs through inhalation, and blastomycosis most often causes a mild to moderate pulmonary infection.? Extrapulmonary disease due to hematogenous spread most commonly affects the skin. ?Bone, prostate, and the central nervous system are also frequently involved.?
Skin lesions of blastomycosis have a characteristic presentation of heaped-up verrucous or nodular lesions with a violaceous hue that may evolve into microabscesses.? Disseminated disease can occur in both immunocompetent and immunocompromised patients, but it is usually more severe in immunocompromised individuals.
Candida
colonizes airways and usually does not cause pneumonia.?
Common causes of esophagitis in patients with HIV
Oral thrush usually present
White plaques throughout esophagus
Biopsy: pseudohyphae
The large majority of patients with Candida esophagitis have oral thrush(although lack of thrush does not exclude the diagnosis); most have prominent dysphagia rather than odynophagia
fluconazole
This patient with AIDS has pain with swallowing, substernal burning, and oral thrush (white oral plaques), indicating likely Candida albicans?esophagitis.? Infectious esophagitis is common in patients with advanced AIDS (CD4 count <100/mm3)
celiac disease
Tissue transglutaminase antibodies can indicate?celiac disease, which usually presents with weight loss, diarrhea, and malabsorption (eg, steatorrhea).
Cellulitis (nonpurulent)
S pyogenes,MSSA, Enterococcus, Haemophilus influenzae, Pseudomonas aeruginosa, and Staphylococcus aureus
Deep dermis & subcutaneous fat
Flat edges with poor demarcation
Indolent (over days) fewer initial systemic symptoms (eg, fever).
Localized (fever later in course)
This patient with erythema, warmth, and swelling of the foot associated with fever and lymphadenopathy has cellulitis, a bacterial infection that involves the deep dermis or subcutaneous fat.? Cellulitis typically occurs when gram-positive skin flora (eg, beta-hemolytic Streptococcus, Staphylococcus aureus) gain access to the subcutaneous space via breaks in the skin (eg, trauma, insect bites, preexisting skin infection).
This patient with chronic interdigital pruritus and skin flaking likely developed cellulitis as a complication of tinea pedis (TP), a dermatophyte infection most commonly caused by Trichophyton rubrum.? TP is one of the most common risk factors for lower extremity cellulitis.? Dermatophytes are generally noninvasive but cause fissuring, erosions, and ulceration that allow bacterial entry into the tissue, particularly when the feet are chronically wet or occluded (eg, by nonbreathable footwear, as in this patient who wears rubber shoes).? Patients with immunosuppression (eg, uncontrolled diabetes) are at particularly high risk of developing both severe TP and secondary cellulitis.
Cellulitis (purulent)
MSSA,MRSA
Purulent drainage
Folliculitis: infected hair follicle
Furuncles: folliculitis ? dermis ? abscess
Carbuncle: multiple furuncles
Chikungunya virus infection
Caribbean islands and subsequently developed fever, rash, and severe polyarthritis, likely indicating chikungunya, an alphavirus infection transmitted by Aedes mosquitoes.
Manifestations typically include high fever; diffuse maculopapular rash; and symmetric, progressive joint pain that is severe enough to interfere with daily activities.? Joint symptoms begin in the distal small joints of the hands and feet but may affect proximal joints over time.? Transient lymphopenia and thrombocytopenia often occur.
Although fever and rash resolve spontaneously in a few days, up to 70% of patients with chikungunya develop chronic arthralgia/arthritis that lasts months or years
Chlamydia psittaci
usually acquired through close contact with birds and causes the abrupt onset of fever, dry cough, and headache.
Psittacosis, caused by Chlamydia psittaci, presents with abrupt-onset cough and headache after exposure to exotic birds
Chlamydia trachomatis
Initial small, shallow ulcers (often missed)
Then painful & fluctuant adenitis (buboes)
Painless
Doxycycline is the first-line treatment for lymphogranuloma venereum caused by Chlamydia trachomatis.? Small (2-3 mm), painless genital ulcers appear and then resolve before the development of painful, suppurative inguinal nodes.?
Clostridium perfringens
causes gas gangrene and manifests with severe pain, bullae, soft tissue crepitus, and signs of systemic toxicity (including shock and multiorgan failure).?
Clostridium tetani
Typical symptoms include tonic contraction and spasm of skeletal muscle (eg, neck stiffness, masseter spasm), which can last up to 4-6 weeks.? The risk for tetanus is greatest in wounds that are deep (eg, puncture wounds) or contain devitalized tissue (eg, burns, crush injuries).
Patients (such as this one) with significant or dirty puncture wounds who have received >3 tetanus toxoid doses but have not received revaccination for tetanus within 5 years should be vaccinated.? This patient has not received Tdap in adulthood and should therefore receive a single dose of Tdap at this time
Unimmunized, uncertain, or <3 tetanus toxoid doses: Tetanus toxoid-containing vaccine*
PLUS TIG
history of a puncture wound (eg, splinter) approximately 1 week prior to symptom onset that leads to inoculation with Clostridium tetani spores.?
Tetanus toxin travels through lower motor neurons to the CNS, where it inactivates inhibitory interneurons.? Common manifestations include masseter muscle spasm (lockjaw [trismus]), muscle pain and stiffness, and difficulty swallowing.
Tetanus is a clinical diagnosis.
Coccidioidomycosis
Coccidioidomycosis is a fungal infection endemic to the southwestern United States; it often manifests as CAP with hilar lymphadenopathy.
predominantly pulmonary infections (“valley fever”).? It has been reported in a wide geographic distribution but is found primarily in the desert Southwest and Central Valley of California.
symptomatic infection is often marked by subacute pulmonary symptoms, chest x-ray usually reveals a unilateral (not bilateral) infiltrate with ipsilateral hilar lymphadenopathy.? Tissue biopsy would show spherules with endospores (not yeasts).
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.?
Confirmation primarily relies on serologic testing, but cultures are often sent.? 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.
condylomata acuminata
Podophyllotoxin and imiquimod are topical medications used to treat condylomata acuminata, genital warts caused by certain serotypes of human papillomavirus.
skin-colored verrucous and filiform papules in the anal/perianal area, penile shaft, or vulvovaginal and cervical areas.
contact dermatitis
erythematous plaques, often associated with vesicle formation, oozing, or crusting.? Itching is typically intense.?
Creutzfeldt-Jakob disease
prion disease that causes personality change, dementia, and (often) myoclonus.
Cryptococcus
Cryptococcus typically causes patchy infiltrates or nodular lesions
Cryptococcal meningoencephalitis
The patient presents with fevers, headaches, and signs of elevated intracranial pressure (eg, vomiting, papilledema).? In immunocompromised patients with HIV, this is most consistent with cryptococcal meningitis, typically seen in patients with CD4 counts <100/mm3.? Cryptococcus neoformans is an invasive fungus acquired by the inhalation of spores that primarily causes pulmonary disease
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)
Neuroimaging is performed to exclude mass lesions, although C neoformans infection rarely causes mass lesions in patients with HIV. ?
Initial: amphotericin B with flucytosine
Maintenance: fluconazole
cryptosporidiosis
CD4<180/mm3
Severe watery diarrhea
Low-grade fever
Weight loss
In this patient with a recent CD4 count of 94/mm3, severe watery diarrhea, weight loss, and low grade fevers, cryptosporidiosis is the most likely diagnosis.
The pathogen is usually self-limited in immunocompetent hosts, but it may cause severe chronic infection in patients with AIDS (particularly those with CD4 counts <180/mm3).? Stool examination with modified acid-fast stain reveals cryptosporidial oocytes
The mainstay of treatment is supportive care and antiretroviral therapy because infection often persists until CD4 counts improve.
Cutaneous larva migrans
a creeping cutaneous eruption caused by dog (Ancylostoma caninum) or cat (A braziliense) hookworm larvae.? Most infections are acquired from walking barefoot on contaminated sand (beaches) or soil.? Humans are incidental hosts, and larvae are typically unable to penetrate the dermal basement membrane.? As a result, cutaneous infection without deeper penetration is the norm.
symptoms usually start with a pruritic, erythematous papule at the site of larvae penetration (which may go unnoticed).? Within a few days, patients develop symptoms related to larvae migration: intensely pruritic, serpiginous, reddish-brown cutaneous tracks.?
Hookworm larvae may cause a papular lesion at the site of entry (usually the lower extremity) and proximal, intensely pruritic, reddish-brown tracks from larval migration.
Cytomegalovirus
CD4<50/mm3
Frequent, small-volume diarrhea
Hematochezia
Abdominal pain
Low-grade fever
Weight loss
Cytomegalovirus (CMV) is a common cause of colitis, esophagitis, or retinitis in patients with AIDS.? However, colonic symptoms typically include frequent, small volume stools that are often bloody
Common causes of esophagitis in patients with HIV
Large, linear ulcers in distal esophagus
Biopsy: intranuclear/intracytoplasmic inclusions
CMV esophagitis is generally marked by large, linear ulcers in the distal esophagus and biopsy evidence of intracytoplasmic and intranuclear inclusions; IV ganciclovir is the treatment of choice.?
Cytomegalovirus typically causes retinitis (eg, floaters, blurry vision) in patients with HIV who have CD4 counts <50/mm3.?
MRI may show periventricular enhancement
CMV may cause retinitis, colitis, pneumonitis, encephalitis, and other organ involvement.
Cytomegalovirus
typically causes an asymptomatic initial infection.? However, a minority (<10%) of patients develop a mononucleosis-like initial illness (closely resembling Epstein-Barr virus [EBV] mononucleosis) with several weeks of fever, malaise, fatigue, absolute lymphocytosis with >10% atypical lymphocytes, and mild elevations in aminotransferase levels.? Compared with EBV, CMV mononucleosis usually causes much milder pharyngitis, lymphadenopathy, and splenomegaly (or these symptoms may be absent).
negative heterophile antibody testing (monospot), and positive CMV IgM serology.?
Men who have sexual encounters with men, such as this patient, have higher rates of CMV seroconversion than the general population and are at increased risk for infection with different CMV strains.
Deep venous thrombosis
lower extremity pain, swelling, and occasionally erythema and fever.? However, the swelling and erythema typically involve the posterior leg or calf,
Dengue fever
usually presents with fever, headache, retro-orbital pain, rash, and significant myalgia and arthralgias.? Patients can also develop hemorrhagic dengue fever with significant hemorrhage in the skin or nose.?
Diphtheria
Diphtheria typically presents with fever, malaise, pharyngitis, and lymphadenopathy.? A gray pseudomembrane may cover the tonsils and oropharynx.
Disseminated gonococcus infection
cause rash and joint symptoms (eg, tenosynovitis, polyarthralgia).? However, the rash is marked by a few scattered pustules or vesicopustules, not a diffuse maculopapular rash.
Polyarthralgia:? Asymmetric pain in multiple distal and proximal joints.
Pustular rash:? Most patients have 2-10 pustular or vesiculopustular lesions on the distal extremities; trunk lesions can also occur.? The palms and soles may or may not be affected.
Tenosynovitis:? Patients report pain over the flexor tendons of multiple distal joints (eg, wrists, ankles, fingers, toes) and/or pain with passive range of motion of the joint.
Systemic signs of infection (eg, fever, chills, malaise) are frequently present. no urogenital symptoms.
Because Neisseria gonorrhoeae grows fastidiously, blood and synovial fluid cultures are frequently negative (fewer than one-third of patients had positive blood cultures in one study); therefore, the diagnosis is usually presumptively established by NAAT of urogenital sites.
Entamoeba histolytica
presents with dysentery, which is characterized by abdominal pain, diarrhea, and bloody stools.
Entamoeba histolytica infections.
Metronidazole-based combination therapy is used to treat Entamoeba histolytica infections.
abdominal pain, fever, diarrhea, and weight loss
Erysipelas
Streptococcus pyogenes
Superficial dermis & lymphatics
Raised, sharply demarcated edges
Rapid spread & onset
Fever early in course
Erysipelas is a skin infection of the upper dermis and superficial lymphatic system most commonly caused by group A?Streptococcus.? Infections take hold in areas of skin disruption, often due to minor trauma, inflammation, concurrent infection, or edema.? Patients rapidly develop systemic symptoms (fever, chills), regional lymphadenitis, and a warm, tender, erythematous rash notable for raised, sharply demarcated borders.?
Haemophilus ducreyi
painful genital papule that progressed to an ulcer, suggesting Haemophilus ducreyi (chancroid) infection.
erythematous papules that evolve into pustules and then erode into painful ulcers.
erythematous base, well-demarcated/undermined borders, and an overlying purulent exudate.? Painful inguinal lymphadenitis is common.
treatment with antibiotics (eg, azithromycin) is typically curative.
Azithromycin or ceftriaxone may be used to treat a chancroid (caused by Haemophilus ducreyi), which is a painful ulcer with an exudative base that may be accompanied by tender, suppurative lymphadenopathy.
Herpangina
high fever, malaise, and throat pain.? Examination of the throat typically shows hyperemic yellow or grayish-white papulovesicles.
Herpes simplex encephalitis
acute (not subacute) fever, headache, seizures, focal deficits, and altered mental status.? Imaging typically reveals unilateral temporal lobe?enhancing lesions with mass effect.
Cognitive and personality changes, as well as focal neurological deficits and/or seizures, are more common in HSV infection due to the temporal lobe involvement (seen on MRI).?
Herpes encephalitis is usually marked by acute constitutional symptoms, focal neurologic deficits, and/or seizure.? The herpes rash is vesicular, Lumbar puncture usually reveals significant red blood cells in the cerebrospinal fluid.
Herpes simplex virus
Pustules, vesicles, or small ulcers on erythematous base
Tender lymphadenopathy
Systemic symptoms common
Herpes simplex lesions are painful and vesicular
Common causes of esophagitis in patients with HIV
Orolabial lesions usually present
Vesicular or ulcerative round/ovoid lesions (“volcano-like”)
Biopsy: multinucleated giant cells
HSV esophagitis is usually marked by endoscopic evidence of small, round-oval, volcano-like esophageal lesions and multinucleated giant cells/intranuclear inclusions on biopsy; acyclovir/valacyclovir is the treatment of choice
painful vesicular lesions on an erythematous base,
Histoplasma capsulatum,
a soil-based fungus with a wide distribution found primarily in the Mississippi and Ohio River valleys.? It usually causes an asymptomatic or mild pulmonary infection.? Immunocompromised patients with disseminated disease may develop papular, crusting skin lesions, but disseminated infection is rare in immunocompetent patients.
a subacute granulomatous pneumonia with yeasts on tissue biopsy.? Although similar findings are seen with Candida pneumonia or blastomycosis, this patient’s history of recent cave exploring suggests infection with Histoplasma capsulatum, a dimorphic fungus endemic to temperate areas of the United States, Asia, Africa, and South/Central America.
most readily in soil contaminated with bat or bird droppings, patients often have a history of vocational (eg, chicken farming) or recreational (eg, cave exploring) activities that increase risk of exposure.
Manifestations usually begin 2-4 weeks after exposure with subacute fever, chills, malaise, headache, myalgia, CP, 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.?
tissue diagnosis, which often reveals granulomas with narrow-based budding yeasts.
Most cases resolve completely over weeks without intervention.? For those with moderate or severe disease, oral itraconazole or intravenous liposomal amphotericin B can be administered.
HIV-associated dementia
cause behavioral and personality changes in those not on antiretroviral therapy.? However, brain imaging with contrast usually shows diffuse brain atrophy, ventricular enlargement, and reduced attenuation of white matter structures.
Hodgkin lymphoma
Hodgkin lymphoma may present with asymptomatic lymphadenopathy, sometimes accompanied by prolonged B symptoms (eg, fever, weight loss, night sweats).
Human monocytic ehrlichiosis
Transmitted by tick vector (Lone Star tick)
Seen in southeastern & south central United States
Flu-like illness (high fever, headache, myalgias, chills)
Neurologic symptoms (confusion)
Rash (<30% in adults) is uncommon (“Rocky Mountain spotted fever without the spots”)
Ehrlichiosis is characterized by an acute febrile illness with malaise and altered mental status.? Ehrlichiosis is not often associated with a rash (<30% in adults) and is described as “Rocky Mountain spotted fever (RMSF) without the spots.”? Neurologic symptoms may include confusion, mental status changes, clonus, and neck stiffness.? Laboratory studies often show leukopenia and/or thrombocytopenia, along with elevated aminotransferases and lactate dehydrogenase.
Intracytoplasmic morulae in monocytes
PCR testing for Ehrlichia chaffeensis/E ewingii
Empiric doxycycline while awaiting confirmatory testing
Infectious mononucleosis
+ Tonsillitis/pharyngitis ? exudates
? Hepatosplenomegaly
fatigue, malaise, sore throat, fever, and lymphadenopathy.? Splenomegaly and, less commonly, hepatomegaly are also seen.
resents with prolonged fever, malaise, and sore throat.? Physical findings include enlarged, erythematous tonsils with exudates; splenomegaly; and lymphadenopathy
Elevated transaminases are also seen in most patients due to mild, transient hepatitis.
In addition, some patients develop autoimmune hemolytic anemia and thrombocytopenia, rare complications of infectious mononucleosis?due to cross-reactivity of EBV-induced antibodies against red blood cells and platelets.? In particular, IgM cold agglutinin antibodies cause complement-mediated destruction of red blood cells.? This hemolysis, which can occur 2-3 weeks after the onset of EBV symptoms, may lead to jaundice, elevated bilirubin, and increased reticulocyte count, as seen in this patient.
leukocytosis and atypical lymphocytes
The heterophile antibody (Monospot) test is specific for EBV and detects EBV antibodies that agglutinate to horse red blood cells.? However, results may be negative early in the course of illness, especially during the first week of symptoms (25% false-negative
Influenza virus
fever, fatigue, myalgia, pharyngitis, and lymphadenopathy and occurs during the winter months
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.
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.? 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).
Streptococcus pneumoniae, Staphylococcus aureus, and (less commonly) Pseudomonas aeruginosa can cause secondary bacterial pneumonia in patients with influenza.? Patients with these infections have high fever, significant leukocytosis (>15,000/mm3), and lobar infiltrates on chest x-ray.?
INH hepatotoxicity
has been associated with hepatotoxicity, which can manifest as a mild INH hepatotoxicity or severe INH hepatitis.
Severe INH hepatitis presents with clinical manifestations similar to those seen with viral hepatitis (eg, fatigue, nausea, flu-like symptoms, jaundice, aminotransferases >10 times upper limit of normal).
In contrast, ~10%-20% of patients taking INH will experience mild, subclinical hepatic injury (mild INH hepatotoxicity) demonstrated only by minor elevations in serum aminotransferases. The prognosis is excellent in these patients and the condition is self-limited, allowing for INH therapy to be maintained with close follow-up.
Because the patient in this question is relatively young and otherwise asymptomatic, she can continue taking INH as long as her liver function tests are regularly monitored and remain only mildly elevated.
innocent “flow” murmur
innocent “flow” murmur due to hyperdynamic circulation from fever.
Jarisch-Herxheimer reaction
Patients with Lyme disease can occasionally develop the Jarisch-Herxheimer reaction following antibiotic initiation.? This reaction (likely reflecting cytokine and immune complex release from killed spirochetes) often causes high fever and worsened systemic symptoms
Klebsiella
Klebsiella and Pseudomonas primarily cause nosocomial pneumonia.? Although Klebsiella can cause aspiration pneumonia, this patient has no clear features (eg, impaired consciousness, dysphagia) that put her at risk for aspirating.
including hospital-acquired pneumonia.
Klebsiella pneumoniae and mixed anaerobes often cause pulmonary infections in those at risk for aspiration (eg, alcoholism).? Symptoms of putrid sputum and infiltrates in the dependent pulmonary lobes (right lower, right middle) are common
Legionella
high fever (>39 C [102.2 F]), pulmonary symptoms (dyspnea, cough), and gastrointestinal symptoms (nausea, vomiting, diarrhea).?
Erythromycin
atypical community-acquired pneumonia with central nervous system (confusion) and gastrointestinal (abdominal pain, diarrhea, hepatitis) features.? The primary environmental source of Legionella pneumophila is water
Recent travel (especially cruise or hotel stay) within the previous 2 weeks
Contaminated potable water in hospitals/nursing homes
Bradycardia relative to high fever
Neurologic symptoms (especially confusion)
Gastrointestinal symptoms (especially diarrhea)
entral nervous system and gastrointestinal involvement to fulminant disease with multi-organ failure.? Relative bradycardia (despite high fever) is a classic association; hyponatremia and mild hepatitis, as in this patient, are frequently seen.? Legionella is an intracellular gram-negative rod, so sputum Gram stain may show neutrophils but no organisms.? The diagnosis can be made by culture, generally from bronchoscopy.? However, Legionella is difficult to recover even when selective media (buffered charcoal yeast extract) are used.? Urine antigen testing is rapidly available, highly specific, and the most common method to confirm the diagnosis
macrolide or fluoroquinolone.
