Drug resistance and its clinical relevance of nontuberculous mycobacteria in Sichuan area

Abstract

Objective To analyze the status of infection and drug resistance of nontuberculous mycobacteria (NTM) and its clinical relevance in Sichuan area. Methods Mycobacteria laboratory specimens from January 2014 to December 2015 in Public Health Clinical Center of Chengdu were retrospectively collected and analyzed. NTM identification was performed by gene chip or 16S rDNA gene sequencing. Drug susceptibility test of NTM was performed using proportion method. Clinical relevance of 87 NTM isolates from patients was analyzed. The chi-square test was used for rates comparison between groups. Results There were 12 460 cases of Mycobacterium culture from January 2014 to December 2015. A total of 3 991 cases (32.0%) were positive for culture and 125 cases of them were nontuberculous mycobacteria. Nine species/complex of NTM were identified. M. chelonae/M. abscessus was the predominant species (42/125, 33.6%), followed by M. intracellulare (37/125, 29.6%) and M. avium (29/125, 23.2%). There was no statistically significant difference of drug resistance within two years (χ2=3.88, P>0.05). All 125 NTM isolates exhibited different degrees of drug resistance to anti-TB drugs. The rate of isoniazid resistance (99.2%) was the highest, followed by rifampicin (97.6%), streptomycin (93.6%), ofloxacin (89.6%), amikacin (85.6%), capreomycin (81.6%), ethambutol (65.6%), kanamycin (58.4%) and clarithromycin (44.8%). Of the 87 NTM isolates from patients, 58 cases (66.7%) were diagnosed with NTM infection. Conclusions The incidence of NTM shows an upward trend during the period from 2014 to 2015 in Sichuan area, and the drug resistance is severe. The clinical relevance of NTM isolations needs further study. Key words: Mycobacterium; Nontuberculous; Drug resistance; Clinical relevance