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Antibiotic-associated diarrhea — ABIM Board MCQ

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HardInfectious DiseaseAntibiotic-associated diarrheaABIM Board

A 41-year-old man with untreated HIV, CD4 count 28/µL, positive Toxoplasma IgG and multiple ring-enhancing brain lesions began pyrimethamine, sulfadiazine and leucovorin. After 12 adherent days he has worsening hemiparesis and enlarging lesions. Which next step is most appropriate?

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Correct answer: B — Obtain stereotactic brain biopsy to evaluate an alternative diagnosis

The best answer is “Obtain stereotactic brain biopsy to evaluate an alternative diagnosis”. More than 90% of patients with toxoplasma encephalitis improve neurologically within about 14 days. Clinical deterioration or absent improvement by 10 to 14 days despite adequate therapy should prompt tissue diagnosis for alternatives such as primary CNS lymphoma. Antibody titers do not monitor response, and corticosteroids can obscure lymphoma without resolving diagnostic failure.

Reference: NIH Adult Opportunistic-Infection Guideline: Toxoplasma Encephalitis: https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/toxoplasmosis