Increasing Incidence of Nontuberculous Mycobacteria, Taiwan, 2000–2008

Abstract

To assess the species distribution and epidemiologic trends of nontuberculous mycobacteria, we examined isolates from patients in Taiwan.During 2000-2008, the proportion increased signifi cantly from 32.3% to 49.8%.Associated disease incidence increased from 2.7 to 10.2 cases per 100,000 patients.Mycobacterium avium complex and M. abscessus were most frequently isolated.I n Taiwan, the incidence of tuberculosis (TB) remains high despite advances in the antimycobacterial therapy and implementation of well-known TB control measures (1).Therefore, patients with acid-fast bacilli (AFB)-positive specimens, especially respiratory samples, are generally presumed to be infected with Mycobacterium tuberculosis and are treated with antituberculosis agents and placed in isolation rooms.Increased isolation of nontuberculous mycobacteria (NTM) causing mycobacterial diseases (2,3) implies that more patients with AFB-positive samples have received inappropriate or unnecessary empirical antituberculous treatment.To help clinicians determine whether to initiate antituberculous treatment, mycobacterial laboratories should provide percentages of NTM isolates among specimens with positive AFB.However, the number and species of NTM from clinical specimens are increasing in the clinical laboratory, and the distribution of NTM species varies by geographic area (4).We thus sought to assess the species distribution of NTM isolates from various clinical specimens and to elucidate the epidemiologic trends of NTM isolates and diseases over a 9-year period in Taiwan.