Session: Poster Session: Resistance in Mycobacteria
Monday, October 27, 2008: 12:00 AM
Room: Hall C
Background: Extensively Drug resistant Tuberculosis (XDR TB) is a global threat. To date however XDR TB has not been reported from Pakistan. In this study we assess the extent of XDR-TB within the Multidrug resistant (MDR) strains. The XDR isolates were genotyped in order to characterize the strain types associated with resistance in this population. Methods: Retrospective analysis was carried out on MTB strains from different parts of the country isolated between January 2004 and December 2007. MDR and XDR strains were identified. Susceptibility against rifampicin, isoniazid, streptomycin, ethambutol, ethionamide, capreomycin, amikacin, kanamycin and ciprofloxacin was on basis of agar proportion method, and against Pyrazinamide using BACTEC. Descriptive, univariate and multivariable analysis was conducted using SPSS version 14. XDR strains were genotyped using spoligotyping. Results: During the study period 7176 MTB strains were isolated from 14 major cities. These included 2528 (35%) MDR strains of which 44 (1.7%) were XDR. Mean age of the XDR patients was 35.03 years. Male: Female ratio was 1.47:1. XDR strain were 100%, 74%, 63%, 21% and 9% resistant to pyrazinamide, ethambutol, streptomycin, capreomycin and ethionamide respectively. Spoligotyping of 39 strains showed that 33 (85%) were grouped into 5 shared types (ST) while 6 (15%) were identified as “Orphan types”. ST distribution included; 33% Central Asian Strain 1 (ST26), 26% MANU1 (ST100), 10% MANU2 (ST54) and 5% poorly defined TB strains T1 (ST53). Conclusions: This is the first report of XDR TB from Pakistan. CAS1 strains previously shown to be predominant in the country also constituted a large proportion of XDR isolates. However our data also shows a high preponderance of MANU genotype within our XDR isolates. Our study provides essential baseline information on XDR-TB isolates for a better understanding and analysis of disease transmission dynamics in this population.