A case of pulmonary Mycobacterium shimoidei infection

Abstract

A 68 year-old male who was ex-smoker presented with fever and cough. Chest radiograph showed infiltrative shadows in both upper lung fields. A sputum smear for acid-fast bacilli was positive. But the isolate was not identified by polymerase chain reaction method. Acid-fast bacilli were cultured from sputum, but the identification was not done by DNA-DNA hybridization method. Mycobacterium shimoidei was identified by 16S ribosomal RNA sequencing with 98.42% matching. Rifampicin, ethambutol, clarithromycin, pyrazinamide, and ciprofloxacin were administered, and the symptom and abnormal shadows on chest radiography improved. And three months later from the initiation of treatment, sputum smear for acid-fast bacilli became negative. Chest CT scan four months after treatments showed decrease of infiltrative shadows. We had treated him for six months, and after that no recurrence occurred.