Diagnostic value of repeat deep sampling and cytocentrifugation in disseminated nocardiosis due to Nocardia brasiliensis with intramuscular and prostatic abscesses in a patient with myelodysplastic syndrome.

Nocardiosis remains diagnostically challenging in immunocompromised patients. We report disseminated nocardiosis due to Nocardia brasiliensis, supporting the role of repeat deep sampling and specimen concentration by cytocentrifugation in enhancing diagnostic yield. An 80-year-old man with myelodysplastic syndrome with low blasts and ring sideroblasts and type 2 diabetes mellitus presented with a three-week history of progressive pain and swelling of the right thigh and left lower leg. One week before symptom onset, the patient received a five-day course of oral levofloxacin for urinary frequency. Contrast-enhanced computed tomography (CT) demonstrated abscesses in the right thigh musculature, the subcutaneous tissue of the left lower leg, and the prostate. An initial smear from the left subcutaneous lesion was negative. Repeat aspiration of the intramuscular abscess in the right thigh, followed by cytocentrifugation, showed beaded, branching, Gram-positive filamentous bacilli, consistent with Nocardia. 16S ribosomal RNA gene sequencing subsequently identified N. brasiliensis. Antimicrobial susceptibility testing supported treatment with oral trimethoprim-sulfamethoxazole, which led to clinical improvement and a decrease in the size of the abscesses on follow-up contrast-enhanced CT. The patient was discharged on hospital day 23. In immunocompromised patients, nocardiosis may involve atypical anatomic sites. When the initial smear is negative, especially after prior antibiotic exposure, prompt repeat sampling with adequate volume from a deeper or alternative site, combined with cytocentrifugation, is essential to avoid delays in diagnosis and treatment.