Abstract:

Objective: To investigate the genotype distribution and prevalence of Mycobacterium tuberculosis (MTB) isolates in Fujian Province, and to analyze the relationship between MTB genotypes and drug resistance. Methods: A total of 477 MTB clinical isolates from tuberculosis drug resistance surveillance sites in Fujian Province from 2017 to 2019 were selected as the research objects. The growth test method of p-nitrobenzoic acid (PNB)/thiophene-2-carboxylic acid hydrazide (TCH) was used for preliminary identification of bacteria. The drug sensitivity test of 9 kinds of anti-tuberculosis drugs (isoniazid (INH), rifampin (RFP), streptomycin (Sm), ethambutol (EMB), kanamycin (Km), ofloxacin (Ofx), capreomycin (Cm), propylamine (Pto), para aminosalicylic acid (PAS)) was carried out using the traditional solid proportion method. The strains were genotyped by the melting curve method of interval oligonucleotide typing (McSpoligotyping). Results: Among the 477 MTB strains, 245 strains (51.4%) were Beijing genotype, 44 strains (9.2%) were in T family (including 2 strains of T, 28 strains of T1, 7 strains of T2, 3 strains of T3 and T4, and 1 strain of T5), 35 strains (7.3%) were in H family (including 13 strains of H, 1 strain of H1, 21 strains of H3), 11 strains (2.3%) were in EAI family (including 10 strains of EAI2-Manila and 1 strain of EAI5), and 3 strains (0.2%) were in LAM3, Manu2 and X1 families, respectively, and the other 139 strains (29.1%) belonged to undefined or unknown families. Cluster analysis showed that the main epidemic types of each genotype family were SIT1 of Beijing family (44.9%, 214/477), SIT53 of T family (2.5%, 12/477), SIT742 of H family (1.9%, 9/477), and SIT19 of EAI family (1.5%, 7/477). The differences among the INH resistance rate of MTB strains of different family were statistically significant (χ²=10.311, P=0.036), the INH resistance rate of the EAI+LAM+Manu+X families was the highest (28.6%, 4/14). There was statistically significant difference among the RFP resistance rate MTB strains of different family (χ²=14.366, P=0.006), the RFP resistance rate of EAI+LAM+Manu+X families was the highest (21.4%, 3/14). There was statistically significant difference among Ofx resistance rate of MTB strains of different families (χ²=23.643, P=0.000), the Ofx resistance rate of H family strains was the highest (17.1%, 6/35). There was statistically significant difference among PAS resistance rate of MTB strains of different families (χ²=9.550, P=0.049), and the PAS resistance rate of strains of undefined family was the highest (4.3%, 6/139). Conclusion: The prevalent MTB genotype in Fujian Province is Beijing family, and the prevalence of the strains of T family, H family, EAI family and the undefined family should be pay attention and the monitoring should be strengthened. The resistance to INH, RFP, Ofx and PAS of MTB strains is related to different genotype families.

Key words: Mycobacterium tuberculosis, Genotype, DNA, ribosomal spacer, Polymerase chain reaction, Drug resistance, bacterial