Molecular epidemiology of TB – Its impact on multidrug-resistant tuberculosis control in China☆

• Main Authors: Biao Xu, Yi Hu, Qi Zhao, Weibing Wang, Weili Jiang, Genming Zhao
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2015-01-01
• Series: International Journal of Mycobacteriology
• Subjects: China; Molecular epidemiology; Multidrug-resistant; Tuberculosis
• Online Access: http://www.ijmyco.org/article.asp?issn=2212-5531;year=2015;volume=4;issue=5;spage=134;epage=134;aulast=Xu;type=0
• ISSN: 2212-5531; 2212-554X

Aims and objectives: The transmission pattern of drug resistant Mycobacterium tuberculosis (MTB) might vary due to the differences in geographic features, socio-economic development and TB epidemic in specific areas and populations. This might also reflect how effectively a TB control program would work. This study aimed to investigate the transmission pattern of drug resistant TB, especially multidrug-resistant (MDR)-TB, and to discuss its implications for an effective TB control program in rural China. Methods: Applying a combination of conventional epidemiology with MIRU-VNTR-based genotyping and DNA sequencing, a descriptive cross-sectional study was performed in two Chinese rural counties: DQ, a long-term DOTS-covered county, and GY, where the DOTS program was launched 11 years later than DQ. Results: In total, 238 bacteriologic confirmed pulmonary TB patients from DQ and 393 from GY diagnosed between 2008 and 2011 were recruited in the study. Of the 631 isolates, 220 (34.9%) were resistant to at least one anti-TB drug, including 95 (15.1%) simultaneously resistant to isoniazid and rifampicin or MDR, albeit with the similar distribution between DQ and GY (32/238 vs. 63/393; p, 0.378). The MIRU-VNTR genotyping revealed 35 isolates from DQ and 86 from GY exhibited 15 and 32 clustering patterns with four patterns shared between two counties. Compared with GY county, DQ had a significantly lower clustering proportion in MTB isolates susceptible to first-line drugs (25/167 vs. 46/198; p, 0.047) and total drug resistant TB isolates (12/71 vs. 44/149; p, 0.044), but a similar clustering proportion in MDR-TB isolates (8/32 vs. 18/63; p, 0.712). A significant higher clustering proportion was observed in the previously treated patients in both counties, but in the sputum smear-positive patients with cavitaries only in GY. Comparing the previously treated patients between the two counties, the proportion of MDR-TB and clustering proportion exhibited a similar distribution, while the average age of previously treated patients in DQ is significantly older than that in GY. Conclusions: A lower proportion of recent transmissions was observed in the county with long-term DOTS implementation. However, DOTS itself might not have worked enough on blocking the recent transmission of MDR-TB. This observation suggests the urgent needs of implementing the Stop-TB strategies; in particular, accelerating the use of rapid molecularbasedTBdiagnosisand drug susceptibility testing, providing active case findings in a high risk population of MDR-TB and enhancing infection control in high MDR-TB burden countries.