ID Flashcards
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Patients undergoing cardiothoracic or orthopedic surgery should be screened for nasal carriage of Staphylococcus aureus and, if positive, should have preoperative decolonization.
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Immune reconstitution inflammatory syndrome is the return of a robust immune response resulting from treatment of HIV that may “unmask” a pre-existing infection; when this occurs, the underlying infection should be treated while antiretroviral therapy is continued.
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This endemic dimorphic fungal infection is known to mimic other diseases, including tuberculosis, histoplasmosis, sarcoidosis, and cancer. The patient is stationed in Bakersfield, California, an epicenter for this infection. In addition, his assignment as a car mechanic, with much of his work likely conducted outside, increases the risk of infection. Another clue is his peripheral eosinophilia. A definitive diagnosis generally is made on the basis of serology and histopathologic analysis of tissue. When coccidioidomycosis is diagnosed, first-line therapy is fluconazole to prevent progressive or disseminated disease
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Guideline-based recommendations for empiric therapy of community-acquired pneumonia requiring ICU admission include a β-lactam (ampicillin-sulbactam, cefotaxime, ceftriaxone, or ceftaroline) to treat Streptococcus pneumoniae, gram-negative bacilli, or Haemophilus influenzae plus an agent active against Legionella, such as a macrolide or quinolone.
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Initial studies for fever of unknown origin in most patients typically include a complete blood count with differential, complete metabolic profile with kidney and liver studies, at least three blood culture sets and cultures of other bodily fluids (such as urine or from other sources based on clinical suspicion), an erythrocyte sedimentation rate, tuberculosis testing, and serology for HIV; it is reasonable to perform chest imaging (radiography or CT) as initial diagnostic imaging.
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Leptospiral meningitis usually develops weeks after exposure, during the second phase of illness, and can present with uveitis, rash, conjunctival suffusion, sepsis, lymphadenopathy, kidney injury, and hepatosplenomegaly.
The cerebrospinal fluid (CSF) findings resemble enteroviral meningitis, but empiric treatment with doxycycline should be started pending confirmation.
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Fulminant Clostridium difficile infections require oral vancomycin plus intravenous metronidazole; vancomycin enemas may also be added if ileus is present.
Oral vancomycin alone for 10 days is recommended for treatment of an initial episode of nonsevere and severe CDI. Oral fidaxomicin can also be used.
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Post–Lyme disease syndrome is a poorly understood sequela of Lyme disease thought to be due to a disordered immunologic response to the preceding infection; most patients slowly improve over a 6-month course, and treatment is directed toward symptom amelioration.
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Rapidly growing, nontuberculous mycobacteria, such as Mycobacterium fortuitum, can produce chronic, nonhealing wounds that do not respond to conventional antimicrobial therapy.
Leprosy is caused by the acid-fast bacillus Mycobacterium leprae, a slow-growing organism. Leprosy should be considered in the setting of chronic skin lesions that fail to respond to treatment of common skin conditions or when sensory loss is observed within lesions or in extremities.
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In patients with a high likelihood of pelvic inflammatory disease without indications for hospitalization, empiric therapy with intramuscular ceftriaxone and oral doxycycline is appropriate without waiting for microbiologic testing results.
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Screening for and possibly treating asymptomatic bacteriuria is supported by only two indications: pregnancy and medical clearance before an invasive urologic procedure.
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This patient has sustained a possible exposure to HIV and should begin postexposure prophylaxis as soon as possible with a three-drug regimen of tenofovir, emtricitabine, and dolutegravir.
Preferred HIV postexposure prophylaxis regimens include tenofovir disoproxil fumarate, emtricitabine, and either dolutegravir or raltegravir and are appropriate whether the exposure was occupational or nonoccupational.
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Acute, uncomplicated pyelonephritis can usually be managed with oral outpatient antimicrobial therapy, with the fluoroquinolones ciprofloxacin and levofloxacin being the preferred, first-line agents.
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Patients with selective IgA deficiency are susceptible to Giardia lamblia infection, manifesting as abdominal cramping, bloating, and chronic diarrhea.
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In patients with potential Zika virus exposure more than 2 weeks previously, testing for Zika virus IgM antibodies is necessary.
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Varicella-zoster virus is a cause of Ramsay Hunt syndrome, which usually presents with ear pain, a vesicular rash in the external ear (although the rash may be absent), and ipsilateral peripheral facial palsy.
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Coxiella- LIVESTOCK
Yersinia pestis infection of the lung causes pneumonic plague. Rodents serve as the primary reservoir for plague
Pneumonic tularemia occurs either after direct inhalation or through secondary spread of Francisella tularensis into the lungs. RABBITS
Chlamydia psittaci is the causative agent of psittacosis, which typically presents as pneumonia associated with abrupt onset of fever, severe headache, and dry cough. BIRD DROPPINGS
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Coagulase-negative Staphylococcus is less virulent than S. aureus and is less likely to cause metastatic infection or endocarditis in patients without prosthetic devices or endovascular hardware in place (such as prosthetic heart valves) and may be treated with simple removal of the intravenous catheter.
Coagulase-negative Staphylococcus CLABSIs often resolve with removal of the catheter. Blood cultures should be repeated after catheter removal to document clearance of the organism. Alternatively, patients with coagulase-negative Staphylococcus CLABSIs can be treated with antibiotics for 5 to 7 days if the catheter is removed and for 10 to 14 days in combination with antibiotic lock therapy if the catheter is not removed.
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Early removal of urinary catheters should be considered when possible, and patients should be monitored for their ability to void spontaneously after catheter removal.
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Human monocytic ehrlichiosis infection is characterized by a nonfocal febrile illness associated with leukopenia, thrombocytopenia, elevated hepatic enzyme levels, and a rapid response to tetracycline.
HME is endemic in the mid-Atlantic, southern, and southeastern United States;
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In patients with health care–associated ventriculitis or meningitis, device removal, if present, should accompany empiric antimicrobial therapy.
Staphylococcus species and enteric gram-negative bacteria are the most common causes, but up to 50% of patients can have negative cultures because more than 50% receive antibiotic therapy before CSF studies are performed, as occurred in this patient.
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First-line treatment for primary pneumonic plague is either streptomycin or gentamicin.
This patient most likely has pneumonic plague caused by the bacteria Yersinia pestis, one of the biologic agents classified as an A-list bioterrorism pathogen because of its high potential lethality and ease of dissemination. Sputum Gram stain (and possibly blood smear) may identify gram-negative coccobacilli demonstrating the classic bipolar staining or “safety pin” shape shown
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Liposomal amphotericin B is the treatment of choice for disseminated histoplasmosis.
Approximately 10% of patients with histoplasmosis develop disseminated infection; if not diagnosed early, the mortality rate is greater than 90%. The treatment of choice for disseminated histoplasmosis is liposomal amphotericin B initially, with de-escalation to itraconazole for several months
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In patients with pneumonia unresponsive to appropriate antibiotic therapy, a noninfectious cause mimicking pneumonia, antibiotic-resistant bacterial infection, infection with a nonbacterial organism, or loculated infection such as an empyema may be the cause.
Antibiotic therapy failure may indicate a noninfectious cause mimicking pneumonia, antibiotic-resistant bacterial infection, infection with a nonbacterial organism, or loculated infection such as an empyema.
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Daptomycin is contraindicated for use in pulmonary infections because it binds to surfactant and does not achieve adequate levels in the alveoli.
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Plasmodium falciparum infection should be suspected if the patient traveled to Africa, symptoms begin soon after return from an endemic area, and the peripheral blood smear shows a high level of parasitemia.
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Patients with spinal epidural abscess who also have neurologic compromise should immediately begin broad-spectrum antimicrobial therapy and undergo surgical drainage.
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Fever is the major manifestation of typhoid fever and is often associated with a relative bradycardia; additional symptoms may include a brief period of diarrhea followed by constipation, abdominal discomfort, nonproductive cough, mild confusion, and transient small blanching skin lesions (rose spots).
Human brucellosis can develop after exposure to one of four Brucella species through contact with viable organisms in secretions or excretions of infected animals, ingestion of undercooked meat or milk products, or, less often, inhalation
Humans acquire leptospirosis after contact with infected urine spread by carrier animals. Classically, illness is biphas
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Genotypic viral resistance testing is recommended immediately after a diagnosis of HIV infection to guide the selection of active agents for the antiretroviral regimen or after virologic failure of a regimen to guide adjustment of antiretroviral therapy.
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Herpes simplex virus type 2 can cause acute aseptic meningitis year round and is the most common cause of recurrent viral meningitis.
HSV-2 is more commonly associated with meningitis and is the most common cause of recurrent meningitis (recurrent benign lymphocytic meningitis). HSV-1 is associated with encephalitis. HSV can cause meningitis year round. CSF findings resemble enteroviral meningitis, with lymphocytic pleocytosis, a normal glucose level, and a mildly elevated protein level as in this patien
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In a patient with Lyme disease and possible central nervous system involvement, positive findings on lumbar puncture can support the diagnosis of neuroborreliosis, which necessitates parenteral therapy with ceftriaxone, cefotaxime, or penicillin.
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Patients with no known direct exposure to anthrax do not require treatment or separation from those who may be infected.
In cases of proven or suspected anthrax in a family member, no specific treatment or isolation procedures are required for others in the household because spread in health care or household settings has never been demonstrated
In patients with confirmed or suspected bioterrorism-related anthrax exposure, postexposure prophylactic antibiotics, taken for 60 days, should be started as soon as possible. Ciprofloxacin, levofloxacin, and doxycycline are the approved drugs
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he most appropriate preventive measure for this patient is daily tenofovir disoproxil fumarate and emtricitabine (TDF-FTC). He has multiple risk factors for acquiring HIV infection, including having sex with multiple partners without consistent condom use. Data support the use of pre-exposure prophylaxis (PrEP) in specific populations with ongoing high risk for infection, such as sexual partners of infected persons, men who have sex with men, and injection drug users.
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Osteomyelitis in a patient with a diabetic foot infection and no evidence of skin or soft tissue infection or sepsis requires a bone biopsy before antibiotics are administered.
Confirming a microbiologic diagnosis is needed before antibiotics can be administered.
Indications for amputation include persistent sepsis, inability to tolerate antibiotic therapy, progressive bone destruction despite therapy, and bone destruction that compromises the mechanical integrity of the foo
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In patients with previously treated syphilis, treponemal serology results will remain positive, but nontreponemal tests will be negative; these patients require no further testing or treatment.
A positive EIA (confirmed by a second test) with a negative RPR is the expected serologic result in a patient who has been treated for syphilis. The treponemal test (EIA) remains positive indefinitely, but the nontreponemal test (RPR or VDRL) should remain negative.
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A screening HIV test result that is positive on the initial antigen/antibody combination immunoassay but negative on the antibody differentiation immunoassay and nucleic acid amplification testing for HIV RNA represents a false-positive result.
If reactive, an HIV-1/2 antibody differentiation immunoassay is performed, which differentiates between HIV-1 and HIV-2 antibodies. If the antibody differentiation assay is reactive for HIV-1 antibody, then HIV-1 infection is confirmed. If the antibody differentiation assay is negative, then testing for HIV RNA by nucleic acid amplification is performed. A negative antibody differentiation assay with a positive HIV RNA test would indicate acute HIV infection (in the “window” period after infection but before antibody development).
