Identification of predominant prevailing nontuberculosis mycobacteria in Hangzhou and analysis of their predisposing factors and drug resistance / 中国人兽共患病学报

ABSTRACT

This study is aim to determine the predominant prevailing nontuberculosis mycobacteria (NTM) in Hangzhou and to understand the predisposing factors and drug resistance of NTM.PNB/TCH growth tests were used to preliminarily identify the NTM in the mycobacterium-positive culture samples from 1 972 patients.The species of NTM isolates were con firmed using mycobacterium molecular linear probe method and sequencing of PCR product of 16S rRNA gene.The influence of sex and age on predisposing factors of NTM was subsequently analyzed.Concentration proportional method was applied to de tect the susceptibility of NTM isolates to armazide,rifampicin,streptomycin,ethambutol,ofloxacin and kanamycin.Results of PNB/TCH growth tests showed that 9.8％ (193/1 972) of the 1 972 mycobacterium-positive culture samples were positive.The mycobacterium molecular linear probe hybridization and PCR product sequencing confirmed that in the 193 samples with positive results of PNB/TCH growth tests,66.3％,18.1％,8.3％ and 7.3％ were infected with NTM alone,two mycobacteria,Mycobacterium tuberculosis and bacteria that not belonging to the genus of Mycobacteria,respectively.In the 173 NTM isolates (128 with single infection and 45 with mixed infection),57.8％ were identified as Mycobacterium intracellulare,followed by Mycobacterium abscessus (12.1％),Mycobacterium kansasi i (9.8％),Mycobacterium chelonei (9.8％) and Mycobacterium avium (5.8％).In the 35 mixed infection samples,28.5％ and 20.0％ were the co-infection of M.intracellulare and M.chelonei with M.tuberculosis,respectively.Male patients infected with NTM were more than female patients (1.67 ∶ 1) and the infection rate (80.4％) of populations with age over 50 years old was significantly high than that with lower than 50 years old (P＜0.01).Pulmonary infection proportion (95.1 ％) of NTM was significantly higher than other positions of body (P＜0.01).100％ of NTM isolates were resistant to armazide while the resistance rates of the isolates against the other 5 antituberculosis drugs were as high as 70.3 ％ 90.6 ％.As the conclusion of this study,M.intracellulare is the predominant prevailing NTM species in the recent years in Hangzhou,NTM mainly causes pulmonary infection and middle-aged and old people are easily infected by NTM.Moreover,NTM isolates have high resistance against commonly used antituberculosis drugs.