Drug resistance of Mycobacterium tuberculosis strains isolated from smear-positive pulmonary tuberculosis patients in Yunnan province: surveillance data analysis

  Objective  To investigate the status of drug resistance of Mycobacterium tuberculosis (MTB) strains isolated from smear-positive pulmonary tuberculosis patients in Yunnan province and to provide evidences for developing strategies for the prevention and treatment of drug resistance tuberculosis.

  Methods  Based on the number of reported smear-positive pulmonary tuberculosis cases in Yunnan province in 2008, 30 counties were selected with probability proportional to size (PPS) sampling and sputum specimens were collected from 5 591 smear-positive pulmonary tuberculosis patients reported in the 30 counties during the periods from 2009 to 2011 and from 2013 to 2015 for isolation, identification, and drug susceptibility test (DST) of MTB.

  Results  Totally 5 319 MTB strains were isolated from all the patients. For all the MTB strains isolated, 269 multidrug-resistant (MDR) and 19 extensively drug-resistant (XDR) strains were detected; the rate of MDR and XDR were 5.06% and 0.36%; the MDR rates were 7.46%, 4.67%, 3.97%, and 4.28% and the XDR rates were 0.39%, 0.19%, 0.00%, and 0.60% for the MTB strains isolated during 2009 – 2011, 2013, 2014, and 2015, respectively, with significant difference in the rates among various time periods (all P < 0.05). Compared to those of the MDR strains isolated during 2009 – 2011, 2013, 2014, and 2015, the ofloxacin- and kanamycin-resistant rate of the isolated non-MDR strains were lower (for ofloxacin-resistant: 1.53% vs. 15.79%, 7.29% vs. 11.58%, 2.90% vs. 14.29%, and 3.60% vs. 14.29%; for kanamycin-resistant: 2.27% vs. 5.00%, 0.31% vs. 2.50%, 2.63% vs. 25.88%, and 1.95% vs. 15.29%) and all the differences in the rates between the two groups were of significance (all P < 0.05), except for the difference in ofloxacin-resistant rate in 2014 and in ofloxacin- and kanamycin-resistant rate during 2009 – 2011.

  Conclusion  The drug resistance rate decrased to some extent for the MTB strains isolated from smear-positive pulmonary tuberculosis patients in Yunnan province in recent years but unreasonable clinic usage of second-line anti-TB drugs such as ofloxacin and kanamycin needs to be concerned for the prevention of MDR among pulmonary tuberculosis patients.