Serial regimen formulation guided by overall treatment effectiveness resulted in treatment outcomes comparable to those obtained with first-line treatment. Confirmatory formal trials in populations with high levels of human immunodeficiency virus coinfection and in populations with a higher initial prevalence of resistance to second-line drugs are required.

Although the heterogeneity of Mycobacterium tuberculosis populations and the existence of mixed infections are now generally accepted, systematic studies on their relative importance are rare. In the present study, 10 individual colonies of each M. tuberculosis isolate (primary isolate) from 97 tuberculosis patients in a primarily human immunodeficiency virus-negative population were screened for heterogeneity and detectable mixed infections by spoligotyping, IS6110-based restriction fragment length polymorphism analysis, and mycobacterial interspersed repetitive unit-variable number of tandem repeat typing. The MICs of antituberculosis drugs for colonies with divergent fingerprints were determined. Infections with different bacterial subpopulations were detected in the samples from eight patients (8.2%), and the frequency of detectable mixed infections in the study population was estimated to be 2.1%. Genotypic variations were found to be independent of the drug susceptibilities, and the various molecular markers evolved independently in most cases. The predominant strains and the primary isolates always had concordant drug susceptibility and MIC testing results. These findings have implications on the interpretation of molecular epidemiology results for patient follow-up and in transmission studies.Tuberculosis (TB) patients have often been assumed to be infected with a single Mycobacterium tuberculosis strain, and infection with one strain is thought to confer immunity to additional M. tuberculosis infections. Therefore, a recurrence of disease after treatment is often considered to be caused by the same strain that caused the original infection. However, cases of reinfection by a second M. tuberculosis strain and occasional infection with more than one strain have been documented (2,5,12,22,31), and the occurrence of mixed infections has now become generally accepted. Infection with multiple strains of M. tuberculosis can seriously confuse interpretation of drug susceptibility testing (DST) results and the detection of epidemiological links (2, 44). However, the frequency of mixed infections and the appreciation of their impact on the phenotypic and the genotypic properties of the primary isolates largely remain unknown, essentially because of the lack of systematic studies on the heterogeneity within M. tuberculosis populations from an individual patient.Almost 30 years ago, Mankiewicz and Liivak (19) used phage typing to analyze the heterogeneity among individual colonies obtained from cultures of specimens isolated from 233 Eskimo patients, leading to the conclusion that 14.1% of the patients tested were simultaneously infected with more than one M. tuberculosis strain. The development of DNA fingerprinting tools has, meanwhile, considerably improved the capacity to distinguish M. tuberculosis strains. Among these tools, IS6110-based restriction fragment length polymorphism (IS6110-RFLP) analysis is considered the standard technique for comparison of M. tuberculosis isolates (32, 33). Other techniques, su...

BackgroundIn Bangladesh DOTS has been provided free of charge since 1993, yet information on access to TB services by different population group is not well documented. The objective of this study was to assess and compare the socio economic position (SEP) of actively detected cases from the community and the cases being routinely detected under National Tuberculosis Control Programme (NTP) in Bangladesh.Methods and FindingsSEP was assessed by validated asset item for each of the 21,427 households included in the national tuberculosis prevalence survey 2007–2009. A principal component analysis generated household scores and categorized in quartiles. The distribution of 33 actively identified cases was compared with the 240 NTP cases over the identical SEP quartiles to evaluate access to TB services by different groups of the population. The population prevalence of tuberculosis was 5 times higher in the lowest quartiles of population (95.4, 95% CI: 48.0–189.7) to highest quartile population (19.5, 95% CI: 6.9–55.0). Among the 33 cases detected during survey, 25 (75.8%) were from lower two quartiles, and the rest 8 (24.3%) were from upper two quartiles. Among TB cases detected passively under NTP, more than half of them 137 (57.1%) were from uppermost two quartiles, 98 (41%) from the second quartile, and 5 (2%) in the lowest quartile of the population. This distribution is not affected when adjusted for other factors or interactions among them.ConclusionsThe findings indicate that despite availability free of charge, DOTS is not equally accessed by the poorer sections of the population. However, these figures should be interpreted with caution since there is a need for additional studies that assess in-depth poverty indicators and its determinants in relation to access of the TB services provided in Bangladesh.

Summaryobjective To determine the relative frequencies of reinfection vs. reactivation or treatment failure in patients from a high tuberculosis incidence setting with a low prevalence of HIV infection.method We performed DNA fingerprinting on serial isolates from one and multiple TB episodes from 97 retreatment patients; 35 patients had been previously cured, whereas 62 had not.results DNA fingerprinting patterns of recurrence Mycobacterium tuberculosis isolates of 5 of the 35 previously cured patients did not match with those of the corresponding initial isolates, indicating reinfection. We did not document reinfection during treatment. Isolates from each of the remaining 30 previously cured patients had identical DNA fingerprinting results, indicating reactivation. DNA fingerprinting patterns of isolates from the 62 patients with persistently positive sputum smears were identical, suggesting treatment failure.conclusion These findings suggest that reinfection is not a common cause of relapse and treatment failure in this rural predominantly HIV-free population despite the high incidence of TB.

HCl 6-10% in water can be recommended for Ziehl-Neelsen destaining above H(2)SO(4). Diluting is easier and safer, and it may cause less confusion with false-positives during rechecking, including a restaining step.