Research Article Reprocessing of Contaminated MGIT 960 Cultures to Improve Availability of Valid Results for Mycobacteria Balaji Subramanyam, Gomathi Sivaramakrishnan, Devi Sangamithrai, Rajkumar Ravi, Kannan Thiruvengadam, Vaishnavi Vijayaragavan, Ayswarya Selvaraju, Srikanth Prasad Tripathy, and Rajesh Mondal Department of Bacteriology, ICMR-National Institute for Research in Tuberculosis, Chennai, India Correspondence should be addressed to Rajesh Mondal; rajesh.m@nirt.res.in Received 20 November 2019; Revised 18 June 2020; Accepted 30 June 2020; Published 18 July 2020 AcademicEditor:ToddR.Callaway Copyright © 2020 Balaji Subramanyam et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Optimal recovery of mycobacteria from the contaminated liquid culture is a challenge. While alternative methods have been suggested to reduce the rate of contamination in the BACTEC MGIT 960 system, reprocessing the contaminated liquid culture improves recovery of Mycobacterium tuberculosis. Among 793 MGIT cultures raised from as many sputum specimens after primarydecontaminationbythestandardNaLC-NaOHmethod,validresultswereavailablefor687(86.6%)as106(13.4%)were contaminated.Reprocessingandreculturingofthecontaminatedculturesincreasedvalidresultsto739(93.2%)andreducedthe contamination rate to 6.8%. Both values were statistically significant. Recovery of the Mycobacterium tuberculosis complex increasedfrom45.6%to48.4%.Validnegativeresultswereavailableforanadditional3.4%.emethodmaybeadoptedtoreduce the rate of contamination and to improve the valid culture results for mycobacteria. 1. Introduction e Center for Disease Control and Prevention (CDC) recommends the use of most efficient and rapid methods availablefordiagnosisoftuberculosis[1].eyincludethe use of at least one liquid medium such as the BACTEC MGIT 960 method for the primary isolation of myco- bacteria [2]. Controlling the overgrowth of normal flora present in sputum is a major challenge while culturing mycobacteriaintheliquidmedium.Overgrowthofnormal floraleadstocontaminationwhichaffectsthesensitivityof detection of the method especially in temperate settings. BACTEC MGIT 960 is currently considered as the gold standardbytheWorldHealthOrganization(WHO)andis used widely for primary isolation as well as drug suscep- tibility testing (DST) of Mycobacterium tuberculosis (MTB).However,highratesofcontaminationinMGIT960 [3] are known to result in lower recovery rate of myco- bacteria [4]. Alternatives such as use of a higher concentration of NaOH up to 1.5% for decontamination of sputum and increasing the volume of the antimicrobial supplement PANTA have been suggested by the manufacturer for re- ducing the rate of contamination. Reprocessing of the contaminated culture and incubating the same are also recommended but rarely practiced [5]. Failure to recover MTB hampers DST and raises concern especially if the cultureiscrucialforpatientmanagementandalsointhecase of extrapulmonary specimens. e present work aims to report on reprocessing of the contaminated liquid culture for optimal recovery of mycobacteria and to reduce the rate of contamination from clinical specimens of a temperate endemic setting. 2. Materials and Methods e observational study was done at the National Institute for Research in Tuberculosis (NIRT), Chennai, India, and was based on retrospective analysis of liquid cultures of all diagnostic and follow-up sputum specimens collected from patients under the NIRT Institutional Ethics Committee- Hindawi International Journal of Microbiology Volume 2020, Article ID 1721020, 3 pages https://doi.org/10.1155/2020/1721020