A case study of disseminated coccidioidomycosis following anti-TB treatment

Background : Mycobacterium and Coccidioides are pathogenic microorganisms that can provoke progressive pulmonary or disseminated granulomatous diseases in humans. Tuberculosis (TB) and coccidioidomycosis have similar clinical and radiological presentations but require different treatments. Coinfection with TB and Coccidioides is exceptionally rare. Diagnosis may be missed even in endemic areas. Case presentation : We present the case of a 34-year-old immunocompetent man with no previous history of TB exposure. Initially, microbiological and molecular tests were positive for Mycobacterium tuberculosis, which showed resistance to rifampicin, and he was discharged with TB treatment. However, after 27 days, he returned with abscesses on his head, left knee, shoulder, and left forefinger. Direct examination of the lesions with KOH and Grocott stain then revealed multiple endospore-containing spherules, confirming coccidioidomycosis. The fungus was further genotyped as Coccidioides posadasii using 621 and GAC microsatellites. Treatment with antimycotic drugs (fluconazole and amphotericin B) led to improvement of the patient's chest X-ray and lesions after several weeks. Conclusions : Though coinfection by Coccidioides and Mycobacterium is extremely rare, it can occur in immunocompetent patients exposed in endemic regions like northern Mexico. Treatment of tuberculosis with antimicrobials may mask or complicate the coccidioidomycosis diagnosis. Early diagnosis and intervention with antifungals such as amphotericin B and fluconazole can significantly improve clinical outcomes.