Evaluation of Thin Layer Agar 7H11 for Direct Susceptibility Testing of Mycobacterium Tuberculosis Complex against Second Line Anti Tuberculosis Drugs on Smear Positive Specimens.

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.

Direct Susceptibility Testing on MGIT 960 TB System: A Rapid Method for Detection of Drug Resistant Tuberculosis.

OBJECTIVE: To evaluate direct drug susceptibility testing on MGIT 960 system for detection of multidrug resistant tuberculosis from smear positive pulmonary specimens. STUDY DESIGN: Cross-sectional analytical study. PLACE AND DURATION OF STUDY: Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi, from July 2016 to September 2017. METHODOLOGY: Smear positive specimens were pretreated according to guidelines and then tested on MGIT 960 TB system for direct drug susceptibility testing (DST) of isoniazid and rifampin. Samples were also processed by gold standard indirect method, which comprises culture and then DST from positive growth by MGIT 960 TB system. RESULTS: Out of 108 specimens, 95 (88%) DST results were reportable. Out of 95 reportable specimens, 17 isolates were resistant to both isoniazid (INH) and rifampin (RIF) by direct DST. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for INH were 92%, 93%, 82%, 97% and 92.6%, respectively; and 95%, 96%, 86.3%, 98.6% and 95.7%, respectively for RIF. Average time to report DST by indirect method was 23.6 ±3.9 days, while it was 11.4 ±2.7 days for the direct method. CONCLUSION: Direct susceptibility testing on MGIT 960 system showed very good agreement when compared with indirect method. Time saving is crucial factor in initiation of early effective therapy, especially in drug resistant cases. Further studies on large scale are required for more accurate evaluation of this method.

Evaluation of Nitrate Reductase Assay for Early Detection of Multi and Extensively Drug Resistance Tuberculosis in our Setup.

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.

Subcutaneous facial mycosis in a child due to Madurella mycetomatis.

Mycetoma is a chronic, granulomatous, subcutaneous, inflammatory disease caused by true fungi (eumycetoma) or filamentous bacteria (actinomycetoma). Eumycetoma usually affects adult males involving limbs and other exposed body parts. Children represent the least commonly encountered age group with this disease. A case of subcutaneous facial mycosis due to Madurella mycetomatis in a three year old child was diagnosed at the Microbiology department Armed Forces Institute of Pathology Rawalpindi, which to our knowledge is the first case reported of its kind. Early diagnosis and timely medical therapy lead to favourable outcome without any surgical intervention.