Mycobacterium simiae pulmonary infection: a case series and literature review.

Incidence of Mycobacterium simiae pulmonary infection is increasing and diagnosis and treatment are challenging. We surveyed the clinical features, risk factors, diagnosis, and management in 20 patients from northeastern Iran diagnosed by line probe assay and confirmed by sequencing the ITS (16S-23S) rRNA region and carried out a literature review using the keywords "pulmonary infection" and "Mycobacterium simiae." The mean age of patients was 55.1 years, with 80% female and 90% diagnosed by sputum. Clinical symptoms included severe cough (90%), sputum production (70%), haemoptysis (50%), and chest pain (35%). Comorbidities included a history of tuberculosis (60%), smoking (40%), or chronic obstructive pulmonary disease (20%). Patients were treated with levofloxacin, clarithromycin, and co-trimoxazole. Except for two patients, the clinical symptoms improved. Mycobacterium simiae pulmonary infection is increasing in people with underlying diseases. Although choosing the most appropriate treatment remains a challenge, combining successful treatments could be useful in treating these patients.