ABSTRACT
Spoligotyping and variable-number tandem repeats (VNTR) typing have been increasingly used for differentiating Mycobacterium tuberculosis strains with low copy numbers of IS6110. However, there are few studies comparing their potential to type the strains originating from South and Southeast Asia where many of the isolates have only a few copies, or even single copy, of IS6110. Here, we evaluated the genotyping of 187M. tuberculosis isolates harboring 1-6 copies of IS6110, available from a population-based study in Chiangrai, northern Thailand during 1998-2000, using spoligotyping and VNTR typing. The low-copy-number isolates constituted about 34% of all M. tuberculosis isolated in the province. Discriminating capacities and cluster identification by the two methods were compared with each other and to those obtained by the standard IS6110-restriction fragment length polymorphism (RFLP) method. We found that VNTR typing based on the studied 10-loci set generated more distinct patterns (151 patterns) than spoligotyping (54 patterns) and IS6110-RFLP (65 patterns). Most of the RFLP- or spoligotyping-defined clusters were subdivided by VNTR typing. Combining IS6110-RFLP with VNTR typing produced 164 distinct patterns and 21.9% of clustered isolates whereas the combination of IS6110-RFLP and spoligotyping gave 103 different patterns and 59.4% of clustered isolates. Our results confirm the utility of VNTR typing as the secondary method of choice for investigating the epidemiology of M. tuberculosis with low copy numbers of IS6110.
Subject(s)
Bacterial Typing Techniques , Minisatellite Repeats/genetics , Mycobacterium tuberculosis/genetics , Repetitive Sequences, Nucleic Acid/genetics , Tuberculosis/genetics , Cluster Analysis , Genotype , Humans , Molecular Epidemiology , Mycobacterium tuberculosis/isolation & purification , Thailand/epidemiology , Tuberculosis/epidemiologyABSTRACT
The first retrospective molecular characterization of Mycobacterium tuberculosis from cerebrospinal fluid of 158 tuberculous meningitis (TBM) in Thailand, collected between 1995 and 2005, was performed by Southern-blot hybridization with an IS6110 probe and spoligotyping on 152 and 147 isolates, respectively. Antituberculous drug susceptibility testing was performed in 149 patients, 118 of whom (79.2%) contained pan-sensitive strains and eight (5.4%) harbored multidrug-resistant M. tuberculosis. IS6110 RFLP typing revealed 110 RFLP patterns with 57.9% of patients infected with the Beijing genotype. This percentage was significantly higher than that in a previous report from pulmonary tuberculosis patients. Fifteen of 18 TBM patients (83%) aged <15 years were infected with Beijing isolates (OR=4.47, p=0.018). There were 40 spoligotypes, with 118 patients (80.3%) being clustered. The biggest cluster, which consisted of 84 patients, was the Beijing spoligotype (57.1%). There were 16 novel spoligotypes from 16 patients compared to the Fourth International Spoligotyping Database, SpolDB4. Sixty-four percent of the patients were male, and the mean age of patients was 33.8 years. Beijing isolates from 2001 to 2005 were found in higher percentages than those from 1995 to 2000, but this difference was not significant (p=0.28).
Subject(s)
Mycobacterium tuberculosis/classification , Mycobacterium tuberculosis/isolation & purification , Tuberculosis, Meningeal/microbiology , Adolescent , Adult , Aged , Aged, 80 and over , Bacterial Typing Techniques , Blotting, Southern , Child , Child, Preschool , Cluster Analysis , DNA, Bacterial/analysis , Drug Resistance, Bacterial , Female , Genotype , Humans , Infant , Male , Microbial Sensitivity Tests , Middle Aged , Molecular Epidemiology , Mycobacterium tuberculosis/genetics , Retrospective Studies , Thailand/epidemiology , Tuberculosis, Meningeal/cerebrospinal fluid , Tuberculosis, Meningeal/epidemiology , Young AdultABSTRACT
To determine whether intact pks15/1 is unique to the W-Beijing family, we investigated 147 Mycobacterium tuberculosis strains with different IS6110 genotypes. Intact pks15/1 was found in 87.8% of cerebrospinal fluid and 84.9% of sputum isolates. It was found not only in W-Beijing strains (approximate, equals 97%) but also in other genotypes (38.5%-100%).
