A 9-month-old infant from a resource-poor country presents with persistent watery diarrhea and malnutrition. An intestinal biopsy reveals blunting of the villi and a characteristic histopathologic lesion where bacteria are intimately attached to the epithelial surface, causing effacement of the host cell microvilli. This “attaching and effacing” lesion is primarily mediated by the binding interaction between which two bacterial protein factors?
A 7-year-old boy living in a rural community in a tropical region of West Africa is brought to a clinic with a large, raised, “raspberry-like” papillomatous lesion on his right lower leg that appeared several weeks ago. The lesion is accompanied by regional lymphadenopathy. This primary lesion is highly characteristic of which infection?
A 9-year-old child living in Thailand, known to have had a dengue infection two years prior, presents with high fever and is later hospitalized with signs of shock, hemoconcentration, and thrombocytopenia. The development of Dengue Hemorrhagic Fever (DHF) in this patient is most strongly associated with which immunopathologic mechanism?
A 7-year-old girl from a coastal county in New Jersey presents in August with an abrupt onset of high fever, headache, and confusion, which rapidly progresses to seizures and coma. A lumbar puncture is performed. Which of the following cerebrospinal fluid (CSF) profiles would be most characteristic of Eastern Equine Encephalitis (EEE) and help differentiate it from other viral encephalitides?
A 16-year-old male from rural Arizona presents with 3 days of fever, myalgias, and headache. He now develops acute dyspnea. Vital signs: temperature 38.7°C (101.66°F), heart rate 115 bpm, respiratory rate 30/min, blood pressure 85/50 mmHg, oxygen saturation 88% on room air. Labs show WBC 19,000/μL with immunoblasts, hematocrit 54%, platelets 58,000/μL. Chest X-ray reveals bilateral interstitial infiltrates. Which virus is most likely responsible?
A 2-year-old boy presents with a limp and refusal to bear weight for 4 days. He is afebrile with a temperature of 37.5°C (99.5°F), has a normal white blood cell count, and a C-reactive protein of 15 mg/L. Aspiration of the hip joint is performed. Which of the following techniques will most significantly improve the likelihood of isolating Kingella kingae by culture from the synovial fluid?
A 9-year-old boy with a two-week history of persistent, worsening cough and low-grade fever is diagnosed with Mycoplasma pneumoniae pneumonia. He completes a 5-day course of azithromycin but shows no clinical improvement after 48 hours and his fever persists. He has no history of international travel. What is the most prudent next step in his management?
A medical student is creating a study guide on the molecular biology of HIV-1 and is reviewing the function of its major genomic regions. They are trying to recall which part of the genome is responsible for producing the viral enzymes that are the targets for several major classes of antiretroviral drugs. The POL gene of the HIV-1 genome encodes for which of the following groups of proteins?
An infant is born to a mother who traveled to Brazil during her first trimester and had a febrile illness with a rash. The infant is born with severe microcephaly. In addition to microcephaly, which of the following neurologic or ocular findings is a specific and characteristic component of the most likely diagnosis?
A 6-year-old boy who plays frequently in a wooded area behind his home in the Midwest presents with lethargy, seizures, and ataxia. An MRI shows diffuse parenchymal inflammation. A lumbar puncture reveals significant eosinophilia. He has concurrent ocular involvement. Which exposure is the most likely source of his infection?
