Pyrazinamide is important in tuberculosis treatment, as it is bactericidal to semidormant mycobacteria not killed by other antituberculosis drugs. Pyrazinamide is also one of the cornerstone drugs retained in the treatment of multidrug-resistant tuberculosis (MDR-TB). However, due to technical difficulties, routine drug susceptibility testing of Mycobacterium tuberculosis for pyrazinamide is, in many laboratories, not performed. The objective of our study was to generate information on pyrazinamide susceptibility among South African MDR and susceptible M. tuberculosis isolates from pulmonary tuberculosis patients. Seventy-one MDR and 59 fully susceptible M. tuberculosis isolates collected during the national surveillance study (

The reemergence of tuberculosis (TB) has become a major health problem worldwide, especially in Asia and Africa. Failure to combat this disease due to nonadherence or inappropriate drug regimens has selected for the emergence of multiple-drug-resistant (MDR) TB. The development of new molecular genotyping techniques has revealed the presence of mixed Mycobacterium tuberculosis infections, which may accelerate the emergence of drug-resistant strains. There are some studies describing the local distribution of circulating strains in South Africa, but to date, reports describing the frequency and distribution of M. tuberculosis genotypes, and specifically MDR genotypes, across the different provinces are limited. Thus, 252 isolates (of which 109 were MDR) from eight of the nine provinces of South Africa were analyzed by spoligotyping. Spoligotyping showed 10 different lineages, and ST53 (11.1%) and ST1 (10.3%) were the most frequent genotypes. Of the 75 different spoligopatterns observed, 20 (7.9%) were previously unreported. Analysis of the mycobacterial interspersed repetitive units of variable-number tandem repeats of the ST53 and ST1 isolates revealed that ϳ54% of the ST53 isolates were of mixed M. tuberculosis subpopulations. Drug resistance (defined as resistance to at least isoniazid and/or rifampin) could only be linked to a history of previous anti-TB treatment (adjusted odds ratio, 4.0; 95% confidence interval, 2.27 to 7.10; P ‫؍‬ <0.0001). This study describes a high diversity of circulating genotypes in South Africa in addition to a high frequency of mixed M. tuberculosis subpopulations among the ST53 isolates. MDR TB in South Africa could not be attributed to the spread of any single lineage.Tuberculosis (TB) is a major cause of illness and death worldwide but especially in Asia and Africa (42). Twenty-two countries designated high TB burden countries account for 80% of all new cases worldwide (42). As of 2008, South Africa was ranked fourth among these, with an incidence rate of 940 cases per 100,000 persons (42) (up from 536 in 2005 [41]). Due to nonadherence to drug regimens or the use of inappropriate drug regimens, the TB epidemic has been largely exacerbated by the emergence of multidrug-resistant (MDR) TB (7).Traditionally, it has been assumed that TB is caused by an infection with a single strain and that recurrences are the result of reactivation of the strain causing the first episode (6, 24, 39). However, it has recently been shown that patients, both human immunodeficiency virus (HIV) positive and HIV negative, in high-incidence settings may have more than one strain in the same sputum sample (24, 39) and that mixed infections may cause complications in the treatment of the disease if a patient is infected with both a sensitive and a resistant Mycobacterium tuberculosis isolate (39). Extensively drug-resistant (XDR) TB strains (defined as resistant to isoniazid [INH] and rifampin [RIF], in addition to any fluoroquinolones and at least one injectable anti-TB drug) (5) were first reported in...

BackgroundIndia has the highest estimated burden of tuberculosis in the world, accounting for 21% of all tuberculosis cases world-wide. However, due to lack of systematic analysis using multiple markers the available information on the genomic diversity of Mycobacterium tuberculosis in India is limited.Methodology/Principal FindingsThus, 65 M. tuberculosis isolates from New Delhi, India were analyzed by spoligotyping, MIRU-VNTR, large deletion PCR typing and single nucleotide polymorphism analysis (SNP). The Central Asian (CAS) 1 _DELHI sub-lineage was the most prevalent sub-lineage comprising 46.2% (n = 30) of all isolates, with shared-type (ST) 26 being the most dominant genotype comprising 24.6% (n = 16) of all isolates. Other sub-lineages observed were: East-African Indian (EAI)-5 (9.2%, n = 6), EAI6_BGD1 (6.2%, n = 4), EAI3_IND, CAS and T1 with 6.2% each (n = 4 each), Beijing (4.6%, n = 3), CAS2 (3.1%, n = 2), and X1 and X2 with 1 isolate each. Genotyping results from five isolates (7.7%) did not match any existing spoligopatterns, and one isolate, ST124, belonged to an undefined lineage. Twenty-six percent of the isolates belonged to the TbD1+ PGG1 genogroup. SNP analysis of the pncA gene revealed a CAS-lineage specific silent mutation, S65S, which was observed for all CAS-lineage isolates (except two ST26 isolates) and in 1 orphan. Mutations in the pncA gene, conferring resistance to pyrazinamide, were observed in 15.4% of all isolates. Collectively, mutations in the rpoB gene, the katG gene and in both rpoB and katG genes, conferring resistance to rifampicin and isoniazid, respectively, were more frequent in CAS1_DELHI isolates compared to non-CAS_DELHI isolates (OR: 3.1, CI95% [1.11, 8.70], P = 0.045). The increased frequency of drug-resistance could not be linked to the patients' history of previous anti-tuberculosis treatment (OR: 1.156, CI95% [0.40, 3.36], P = 0.79). Fifty-six percent of all new tuberculosis patients had mutations in either the katG gene or the rpoB gene, or in both katG and rpoB genes.ConclusionCAS1_DELHI isolates circulating in New Delhi, India have a high frequency of mutations in the rpoB and katG genes. A silent mutation (S65S) in the pncA gene can be used as a putative genetic marker for CAS-lineage isolates.