ABSTRACT
Purpose: The emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is a major public health problem. The diagnosis of MDR-TB is of paramount importance in establishing appropriate clinical management and infection control measures. The aim of this study was to evaluate drug resistance and mutational patterns in clinical isolates MDR-TB by GenoType® MTBDRplus assay. Material and Methods: A total of 350 non-repeated sputum specimens were collected from highly suspected drug-resistant pulmonary tuberculosis (PTB) cases; which were processed by microscopy, culture, differentiation and first line drug susceptibility testing (DST) using BacT/ALERT 3D system. Results: Among a total of 125 mycobacterium tuberculosis complex (MTBC) strains, readable results were obtained from 120 (96%) strains by GenoType® MTBDRplus assay. Only 45 MDR-TB isolates were analysed for the performance, frequency and mutational patterns by GenoType® MTBDRplus assay. The sensitivity of the GenoType® MDRTBplus assay for detecting individual resistance to rifampicin (RIF), isoniazid (INH) and multidrug resistance was found to be 95.8%, 96.3% and 97.7%, respectively. Mutation in codon S531L of the rpoB gene and codon S315T1 of katG genes were dominated in MDR-TB strains, respectively (P < 0.05). Conclusions: The GenoType® MTBDRplus assay is highly sensitive with short turnaround times and a rapid test for the detection of the most common mutations conferring resistance in MDR-TB strains that can readily be included in a routine laboratory workflow.
ABSTRACT
Purpose: India has a high burden of drug-resistant tuberculosis (TB), although there is little data on multidrug-resistant tuberculosis (MDR-TB). Although MDR-TB has existed for long time in India, very few diagnostic laboratories are well-equipped to test drug sensitivity. The objectives of this study were to determine the prevalence of MDR-TB, first-line drug resistance patterns and its changing trends in northern India in the 4 years. Materials and Methods: This was a prospective study from July 2007 to December 2010. Microscopy, culture by Bactec460 and p-nitro-α-acetylamino-β-hydroxypropiophenone (NAP) test was performed to isolate and identify Mycobacterium tuberculosis (M. tb) complex (MTBC). Drug sensitivity testing (DST) was performed by 1% proportional method (Bactec460) for four drugs: Rifampicin, isoniazid, ethambutol and streptomycin. Various clinical and demographical profiles were evaluated to analyse risk factors for development of drug resistance. Results: We found the overall prevalence rate of MDR-TB to be 38.8%, increasing from 36.4% in 2007 to 40.8% in 2010. we found that the prevalence of MDR-TB in new and previously treated cases was 29.1% and 43.3% ( P < 0.05; CI 95%). The increasing trend of MDR-TB was more likely in pulmonary TB when compared with extra-pulmonary TB ( P < 0.05; CI 95%). Conclusions: we found a high prevalence (38.8%) of MDR-TB both in new cases (29.1%) and previously treated cases (43.3%).This study strongly highlights the need to make strategies for testing, surveillance, monitoring and management of such drug-resistant cases.
ABSTRACT
Purpose: Extrapulmonary tuberculosis (EPTB) is emerging problem in developing and developed countries. The diagnosis of EPTB in its different clinical presentations remains a true challenge. IS6110-based polymerase chain reaction (PCR) is used for rapid identification and positivity rate of the Mycobacterium tuberculosis complex in clinical isolates of different sites of EPTB. The present study was carried out to study the prevalence of M. tuberculosis complex in clinical isolates of EPTB at tertiary care centres in Lucknow. Materials and Methods: Seven hundred fifty-six specimens were collected from the suspected cases of EPTB which were processed for Mycobacteria by Ziehl Neelson (ZN) staining and BACTEC culture. All the specimens were also processed for IS6110-based PCR amplification with primers targeting 123 bp fragment of insertion element IS6110 of the M. tuberculosis complex. Results: Of these 756 specimens, 71(9.3%) were positive for acid fast bacilli (AFB) by ZN staining, 227(30.1%) were positive for mycobacteria by BACTEC culture and IS6110 PCR were positive for M. tuberculosis complex in 165 (20.7%) isolates. We found a significant difference in sensitivities of different tests (P<0.05). Conclusions: This study reveals the positivity of M. tuberculosis complex in clinical isolates of EPTB case in tertiary care hospitals in Northern India. 72.7% of M. tuberculosis complex was confirmed by IS6110-PCR in culture isolates from different sites of EPTB. The high prevalence of the M. tuberculosis complex was seen in lymph node aspirate and synovial fluid. However, utility of PCR may play a potentially significant role in strengthening the diagnosis of EPTB especially targeting IS6110.