Genotyping of Mycobacterium tuberculosis by Spoligotyping

Abstract

Tuberculosis (TB) remains an infectious disease causing a public health problem. Presence of different lineages of Mycobacterium tuberculosis complex (MTC) has been noted while there are very limited genotype data available pertaining strains circulated in Thailand. Genotypic method is an epide-miological tool to differentiate local strains and allow the comparison of strains with global isolates. Genotyping is useful for epidemiological investigation and tracking of TB transmission. The genotypes elucidate diversity of strains circulating and the genetic link among the isolates. This study manipulated spoligotyping and aimed to investigate strains circulating in Uttaradit, Phitsanulok, Sukhothai and Phetchabun provinces of Thailand. A total of 162 MTC isolates collected from pulmonary tuberculosis patients were genotyped by spoligotyping, and the strains were compared with those in the international spoligotype database (SpolDB4). Altogether 34 different spoligotype patterns were identified; and new genotypes were found as unidentified families or had individual non-clustering genotypes of M. tuberculosis. The East African-Indian (EAI) groups were the predominant strains followed by Beijing, H3, U, T1, BOV, S and Beijing Like. The proportions of majorities, EAI and Beijing were 43.30% (71/162) and 35.80% (58/162), respectively. EAI2_NTB (Nonthaburi) was the most frequent spoligotype among the EAI groups. In addition, 2 isolates were identified to be Mycobacterium bovis suggesting the transmission of tuberculosis between human and animals. Therefore, spoligotyping revealed the diversity of MTC strains circulating in this region. The major and the minor groups as well as the new MTC strains could be identified. Thus, data of genotypes should be useful in supporting surveillance and control of tuberculosis.