Mycobacterium xenopi pulmonary disease - epidemiology and clinical features in non-immunocompromised patients.

Objectives: The genus Mycobacterium has more than 120 well-characterized species. Although the incidence of tuberculosis has decreased over the studied period, other, non-tuberculous mycobacteria (NTM) are isolated more often. Since, Mycobacterium xenopi is the most frequent NTM isolate in Croatia we studied its epidemiology and clinical relevance.

Methods: We performed a retrospective study over a 25-year period determining epidemiology, radiological findings and clinical importance of M. xenopi infection, obtaining data from archives in health care institutions from all over the country.

Results: We detected 40 patients with a positive isolate of M. xenopi. Twenty-four patients met American Thoracic Society criteria for pulmonary disease. Eighteen (90%) of treated patients were male, on average 61.7 years old. Nineteen (95%) patients lived in towns. Most of them had comorbid disease, 18 (90%), with chronic obstructive pulmonary disease (COPD) being the most frequent, found in 11 (55%) patients. All patients were immunocompetent. We found COPD as the most frequent comorbid disease in the group of patients with worse treatment response (n=8; 80%), while in patients with good treatment response COPD was less frequent (n=3; 30%). Differences in the proportions of patients with COPD were significant (p=0.037).

Conclusion: In patients with M. xenopi pulmonary infection, COPD is a predisposing condition, and as a comorbid disease, is an important prognostic factor for treatment response.