Nocardiosis — SCE Infectious Diseases MCQ

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HardRespiratory InfectionNocardiosisSCE Infectious Diseases

A renal-transplant recipient has a cavitating pulmonary lesion. Culture grows an aerobic, branching, beaded Gram-positive filamentous organism that is weakly acid-fast. Which genus is most likely?

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Correct answer: C — Nocardia

Nocardia species are aerobic branching filamentous actinomycetes with variable or partial acid-fastness and are important causes of pulmonary and disseminated disease in immunocompromised hosts. Actinomyces is anaerobic and non-acid-fast; mycobacteria are acid-fast rods rather than branching Gram-positive filaments.

Reference: UK SMI ID 10: Identification of aerobic actinomycetes. https://www.rcpath.org/asset/CE08D742-B58E-4E8D-986C43A75AC367C3/