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Objective To evaluate performance of thin layer agar (TLA) 7H11 method for detection of ofloxacin (OFX) and kanamycin (KM) resistance in smear positive clinical specimens of patients with tuberculosis comparing the results with gold standard MGIT 960 system. Study design Cross-sectional validation study. Place and duration of study Department of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from April to September 2017. Methodology Acid fast bacilli (AFB) smear positive specimens submitted at the study place, were inoculated on TLA 7H11 agar. Growth was examined along with susceptibility of OFX and KM and compared with gold standard MGIT 960 system. Results One hundred and sixty specimens were evaluated. Sensitivity and specificity of TLA for OFX was found to be 100% and 99.3%, respectively; and PPV and NPV was found to be 90.9% and 100%, respectively. Overall diagnostic accuracy was 99.38%. Sensitivity and specificity of TLA for KM was found to be 80% and 100%, respectively. PPV and NPV was found to be 100% and 99.36%, respectively. Overall diagnostic accuracy was 99.38%. Conclusion Thin layer agar is reliable, easy to perform and cost effective technique not only for rapid detection of MTB but also for drug susceptibility (DST) of second line anti TB agents. It is a suitable alternative to culture on LJ medium and can also be alternative to MGIT 960 system in resource-poor settings.

Objective To evaluate the performance of nitrate reductase assay on smear positive pulmonary specimens for detection of multi and extensively drug resistant tuberculosis simultaneously. Study design Cross-sectional analytical study. Place and duration of study Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi from June to December 2016. Methodology Smear positive pulmonary samples were processed both by nitrate reductase method on Lowenstein Jenson medium and also inoculated on gold standard Bactec MGIT 960 TB system. All the specimens were first digested and decontaminated according to standard protocol before inoculation. Results Out of total 76 samples, three did not give color and, therefore, were excluded from the final data analysis. Among the remaining 73 samples, mycobacterial index was: 28 specimens were having 1+ (1-9 bacilli/100 fields), 26 samples were 2+ (1-9 bacilli/ field), and 19 samples were having 3+ index (>9 bacilli/field). The respective sensitivity and specificity were 84% and 100% for isoniazid (INH); 82% and 100% for rifampin (RIF); 67% and 100% for amikacin (AK); and both 100% for ofloxacin (OFX). Overall agreement in case of INH, RIF, AK, and OFX was 94.5%, 97.2%, 98.6% and100%, respectively. Overall average agreement was 97.5%. Conclusion Nitrate reductase assay is a reliable, low cost and accurate method that can be used for early for diagnosis of multi and extensively drug resistant tuberculosis.