Comparison evaluation between gene Xpert Mtb/Rif and multiplex PCR for rapid diagnosis of mycobacterium tuberculosis.

OBJECTIVE: To compare the efficacy of Gene Xpert mycobacterium tuberculosis-rifampicin and multiplex polymerase chain reacton for the detection of mycobacterium tuberculosis and Rifampicin resistance. METHODS: The cross-sectional validation study was conducted at the Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from March to October 2018, and comprised mycobacterium tuberculosis-positive rifampicin-resistant and rifampicin-susceptible samples, with the latter acting as negative controls. Gene Xpert mycobacterium tuberculosis-rifampicin assasy and multiplex polymerase chain reacton were applied simultaneously and compared with gold standard mycobacterium growth indicator tube 960. Data was analysed using SPSS 24. RESULTS: Of the 192 samples, 84(44%) were culture-positive rifampicin-resistant and 108(56%) were culture-positive rifampicin-susceptible. Overall, 84(44%) were found positive. Gene Xpert mycobacterium tuberculosis-rifampicin assay detected all 84(100%) rifampicin-resistant samples, while multiplex polymerase chain reacton detected 44(52.3%) such samples. Sensitivity, specificity, positive predictive value and negative predictive value of Gene Xpert were 100% each respectively, while the corresponding values for multiplex polymerase chain reacton were 52%, 100%, 100% and 72% respectively. CONCLUSIONS: Molecular detection of mycobacterium tuberculosis and resistance by Gene Xpert and multiplex polymerase chain reacton simultaneously was found to be a rapid and cost-effective method.

Multiplex PCR for Rapid Diagnosis of Drug Resistant Mycobacterium Tuberculosis.

OBJECTIVE: To evaluate a multiplex PCR for rapid diagnosis of drug resistant mycobacterium tuberculosis (MTB) strain. STUDY DESIGN: Cross-sectional observational study. PLACE AND DURATION OF STUDY: Department of Microbiology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from January to September 2018. METHODOLOGY: Over a period of 8 months, a total of 84 cultured positive samples were included in the study using nonprobability sampling techniques. MTB isolates were phenotypically characterised using MGIT 960 system for antituberculosis agents including rifampicin (RIF), isoniazid (INH), ethambutol (EMB) and Streptomycin. The DNA was extracted using Gentra system DNA extraction kit. The multiplex PCR was optimised for genetic characterisation of MTB samples for rpo B (rifampicin), kat G (isoniazid) and emb B (ethambutol) gene. The gel electrophoresis was performed to observe comparative banding pattern of amplified gene products. RESULTS: For detecting drug resistance, the specificity and sensitivity of multiplex PCR in isolates was 100% and 100% for rifampicin, 100% and 71% for isoniazid, and 100% and 60% for ethambutol, respectively. When compared to phenotypically resistance results, the positive predictive value (PPV) was 100% each and the negative predictive value (NPV) was calculated to be 100%, 74% and 71% for RIF, INH and EMB, respectively. CONCLUSION: Multiplex PCR is a useful gadget for quick determination of drug-resistant TB in specimens, hence permitting an initial therapeutic approach. However, for accurate management of patients, phenotypic method should be used to confirm results.