A 14-year-old adolescent weighing 45 kg presents to the emergency department 12 hours after a high-risk sexual exposure. The source’s HIV status is unknown. Which of the following is the preferred 28-day, three-drug postexposure prevention (PEP) regimen for this patient?
A 17-year-old male who lived in a filariasis-endemic area for many years presents with paroxysmal nocturnal cough, dyspnea, and profound eosinophilia (> 2,000/μL). His chest x-ray shows diffuse miliary lesions. Repeated blood smears for microfilariae are negative. What is the most likely diagnosis?
A 2-month-old infant is diagnosed with infant botulism. The infant’s descending, flaccid paralysis is a direct result of botulinum toxin’s action at the neuromuscular junction. Which of the following describes the specific molecular mechanism of the toxin that leads to paralysis?
An 11-year-old heart transplant recipient presents with a headache and new-onset seizures. An MRI of the brain reveals a solitary, ring-enhancing abscess. A biopsy and culture identify Cladophialophora bantiana, a cause of phaeohyphomycosis. In addition to voriconazole therapy, what is the most critical factor for survival in this patient?
A 13-month-old child presents with a febrile seizure. Workup reveals a primary Human Herpesvirus 6B infection. MRI of the brain is performed due to the prolonged nature of the seizure. Which specific brain structures are most likely to show areas of hyperintense signal on T2 weighted images in cases of HHV-6B associated encephalitis?
A 17-year-old male returning from Central Africa presents with transient, localized, non-erythematous subcutaneous swelling over his wrist and reports seeing a “worm” move across his eye. He is diagnosed with loiasis and a blood smear shows a high microfilarial load. Before starting diethylcarbamazine (DEC), what is the most critical co-infection to rule out to prevent severe adverse reactions?
A 17-year-old male is brought to the emergency department after a motorcycle accident resulting in a deep, contaminated crush injury to his thigh. Twelve hours later, the area is markedly swollen with significant crepitus, and the patient complains of severe pain that seems disproportionate to the wound’s appearance. An exudate smear shows gram-positive bacilli but very few leukocytes. This presentation is highly suggestive of which diagnosis?
A 12-year-old boy from an endemic region in South America is being treated for paracoccidioidomycosis with itraconazole. During therapy, he develops new, enlarging lymph nodes, fistula formation, and fever. This paradoxical worsening is suspected to be an inflammatory reaction. In addition to continuing antifungal therapy, what other treatment is recommended?
An 8-year-old boy from a region in Africa where Human Herpesvirus 8 is endemic presents with aggressive, widespread cutaneous nodules and visceral involvement. A diagnosis of endemic Kaposi sarcoma is made. The pathogenesis of this and other HHV-8 associated lymphoproliferative disorders involves multiple virally-encoded proteins that manipulate host cell processes. Which of the following is a key pathogenic mechanism of HHV-8?
A 2-year-old child with diarrhea is infected with Entamoeba histolytica. Research indicates that the gut microbiome can influence the pathogenicity of this organism. The presence of which specific bacteria has been associated with increased rates of diarrhea in children infected with E. histolytica?
