Molecular Typing Characteristic and Drug Susceptibility Analysis of Mycobacterium tuberculosis Isolates from Zigong, China

Abstract

China is one of the 22 countries with high TB burden worldwide, and Sichuan contained the second-largest number of TB cases among all of the Chinese provinces. But the characteristics of Mycobacterium tuberculosis circulated in Zigong, Sichuan, were still unknown. To investigate the character and drug resistance profile, 265 clinical isolates were cultured from tuberculosis patient's sputum samples in the year of 2010, of which the genetic profile was determined by using Spoligotyping and MIRU-VNTR typing methods, and the drug sensibility testing to the four first-line and four second-line antituberculosis (anti-TB) drugs was performed by using proportion method on Lowenstein-Jensen (L-J) media. The major Spoligotype was Beijing family (143/265, 53.96%), followed by T (80/265, 30.19%) and H (9/265, 3.40%) genotypes; the total Hunter-Gaston discrimination index (HGDI) of the 24 loci MIRU-VNTR was 0.9995. About 27.17% (72/265) of the isolates were resistant to at least one of the eight tested anti-TB drugs, and for Beijing and non-Beijing family isolates the proportion of drug resistance was 28.47% (41/144) and 25.62% (31/121), respectively. That is, the most prevalent genotype here was Beijing family, and the 24 loci VNTR analysis could supply a high resolution for genotyping, and Beijing and non-Beijing isolates had no difference (p > 0.05) for drug resistance.