Multidrug-resistant tuberculosis in Bangladesh: results from a sentinel surveillance system.

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) is a serious obstacle to successful TB control. The 2010-2011 Bangladesh Drug Resistance Survey (DRS) showed MDR-TB prevalence to be 7% overall, 1.4% in new and 28.5% in previously treated patients. We aimed to determine the rate of MDR-TB in selected sentinel sites in Bangladesh. METHODS: Fourteen hospitals from the seven divisions in Bangladesh were selected as sentinel surveillance sites. Newly registered TB patients were systematically enrolled from August 2011 to December 2014. Sputum specimens were processed for culture and drug susceptibility testing by the proportion method using Löwenstein-Jensen medium. RESULTS: Specimens from 1906 (84%) of 2270 enrolled patients were analysed. Isolates from 61 (3.2%) were identified as having MDR-TB. The proportion of MDR-TB was 2.3% among new and 13.8% among previously treated TB patients (P < 0.001). The overall proportion of MDR-TB was 3.2%:3.5% in males and 2.3% in females; by age, the MDR-TB rate was highest (5.2%) in those aged 65 years. CONCLUSIONS: The high proportion of MDR-TB among new patients found in this sentinel surveillance significantly differs from that reported in the DRS. While the sentinel surveillance sites were not designed to be nationally representative, it is worrying to observe a higher number of MDR-TB cases among new patients.

Comparison of TaqMan(®) Array Card and MYCOTB(TM) with conventional phenotypic susceptibility testing in MDR-TB.

BACKGROUND: Although phenotypic drug susceptibility testing (DST) is endorsed as the standard for second-line drug testing of Mycobacterium tuberculosis, it is slow and laborious. METHODS: We evaluated the accuracy of two faster, easier methodologies that provide results for multiple drugs: a genotypic TaqMan(®) Array Card (TAC) and the Sensititre(®) MYCOTB(TM) plate. Both methods were tested at three central laboratories in Bangladesh, Tanzania, and Thailand with 212 multidrug-resistant tuberculosis (MDR-TB) isolates and compared with the laboratories' phenotypic method in use. RESULTS: The overall accuracy for ethambutol, streptomycin, amikacin, kanamycin, ofloxacin, and moxifloxacin vs. the phenotypic standard was 87% for TAC (range 70-99) and 88% for the MYCOTB plate (range 76-98). To adjudicate discordances, we re-defined the standard as the consensus of the three methods, against which the TAC and MYCOTB plate yielded 94-95% accuracy, while the phenotypic result yielded 93%. Some isolates with genotypic mutations and high minimum inhibitory concentration (MIC) were phenotypically susceptible, and some isolates without mutations and low MIC were phenotypically resistant, questioning the phenotypic standard. CONCLUSIONS: In our view, the TAC, the MYCOTB plate, and the conventional phenotypic method have similar performance for second-line drugs; however, the former methods offer speed, throughput, and quantitative DST information.