Infectious Disease Management Flashcards

A 28-year-old man presents with genital ulcers and painful inguinal lymphadenopathy (buboes). He recently returned from a trip to Africa. The ulcers are soft and painful. What is the most likely diagnosis and treatment?

Answer: Chancroid; azithromycin 1g single dose

Chancroid (Haemophilus ducreyi) presents with painful soft ulcers and suppurative buboes; azithromycin 1g PO single dose is one of the recommended treatments.

A 50-year-old woman on long-term prednisone for rheumatoid arthritis develops disseminated Strongyloides infection. What is the treatment?

Answer: Ivermectin 200mcg/kg daily x 2 days

Ivermectin is the drug of choice for Strongyloides stercoralis; in disseminated disease, it is given daily until stool exams are negative for 2 consecutive weeks.

A 40-year-old HIV-positive man (CD4 40) on antiretrovirals develops vision loss. Fundoscopic exam shows yellow-white perivascular exudates with hemorrhage ('pizza pie' appearance). What is the diagnosis and treatment?

Answer: CMV retinitis; IV ganciclovir or oral valganciclovir

CMV retinitis in advanced AIDS presents with the classic 'pizza pie' fundoscopic appearance and is treated with valganciclovir 900mg BID for induction followed by maintenance therapy.

A 65-year-old immunocompetent man presents with fever, altered mental status, and CSF pleocytosis with lymphocyte predominance, elevated protein, and normal glucose. HSV-1 encephalitis is suspected. What test confirms the diagnosis?

Answer: CSF HSV PCR

CSF HSV PCR is the diagnostic test of choice for HSV encephalitis, with sensitivity >95% and specificity >99%, replacing brain biopsy as the gold standard.

A 45-year-old patient from the Ohio River Valley presents with fever, weight loss, and mediastinal lymphadenopathy. BAL reveals intracellular yeast within macrophages. What is the treatment for severe disseminated histoplasmosis?

Answer: Liposomal amphotericin B followed by itraconazole

Severe or disseminated histoplasmosis is treated with liposomal amphotericin B for induction (1-2 weeks) followed by step-down to itraconazole for 12 months.

A 70-year-old nursing home resident develops fever, productive cough, and hypoxia. Urinary antigen is positive. She has sulfa allergy. CXR shows lobar consolidation. What is the most likely pathogen and first-line treatment?

Answer: Legionella pneumophila; azithromycin or fluoroquinolone

Positive urinary antigen in pneumonia diagnoses Legionella; first-line treatment is a macrolide (azithromycin) or respiratory fluoroquinolone (levofloxacin).

A 32-year-old woman with no prior medical history presents with fever, myalgias, and rash one week after tick removal in New England. CBC shows leukopenia and thrombocytopenia. What is the most likely diagnosis?

Answer: Anaplasmosis (Anaplasma phagocytophilum)

Anaplasmosis (formerly HME/HGA) presents with fever, leukopenia, thrombocytopenia, and elevated transaminases after Ixodes tick bite in the Northeast; treated with doxycycline.