Abstract
The aim of this study was to characterize the genotypes of Mycobacterium tuberculosis (MT) in isolates obtained from Henan, China, and to study the distribution features of Beijing strains in Henan. A total of 443 MT strains isolated in Henan Province were tested for susceptibility to isonicotinylhydrazide (INH), rifampicin (RFP), ethambutol (EMB) and streptomycin (SM), and genotyped by spoligotyping. The clustering of genotypes revealed 4 gene clusters (Beijing and Beijing-like, T, Manu, and S and LAM3) and 24 genotypes. In total, 387 (87.4%) of the strains were Beijing strains. The frequency of multidrug-resistant (MDR) strains was significantly higher in the Beijing and Beijing-like strains than in the other strains (χ2=4.6564, P<0.05). However, the percentages of drug resistance and sensitivity in the Beijing strains were almost the same as those in the non-Beijing strains. The proportion of Beijing strains in the ≤60-year-old TB patients was significantly higher than in the >60-year-old TB patients (χ2=32.053, P<0.001). The distribution of Beijing strains deceased gradually from the east to the west in Henan Province (P<0.0001). The data demonstrate that the Beijing genotype is a major type in the area and may be related to enhanced transmissibility. The transmission of Beijing family strains has increased in Henan and its incidence is highest in the east of Henan. The MDR strains were significant in the spread of MT.
Highlights
Mycobacterium tuberculosis (MT) is seriously harmful to human survival and health
MDR-TB accounted for 7.8% of the MT Beijing strains, but multidrug resistance did not emerge in the non-Beijing families, in types T1, T2, T3, T4 and other types
Age significantly correlated with the distribution of the Beijing family strains (Table IV)
Summary
Mycobacterium tuberculosis (MT) is seriously harmful to human survival and health. Currently it constitutes the second major cause of mortality due to infectious disease worldwide. The 4th international spoligotyping database, SpolDB4, describes 1939 shared types (STs) of MT, representing a total of 39,295 strains from 122 countries. These strains have been tentatively classified into 62 clades and/ or lineages using a mixed expert-based and bioinformatics approach [6]. The MT Beijing strain is widely distributed in Far East Asia and approximately 86% of clinical isolates in China belong to this family [3]. This finding has had a major impact on the epidemiological study of MT. Certain MT Beijing‐like genotypes are characterized in terms of deletions of spacers 1-34 and by certain individual deletions in spacers 35-43
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