Comparison of Bact/Alert -3D Automated Culture System and Conventional Culture Method for Mycobacterium tuberculosis from Extrapulmonary Specimens of the Patients Attending SKNMC and GH

摘要

Introduction: In extrapulmonary samples, very low yield of mycobacteria results in a low sensitivity of acid fast bacilli (AFB) smear and culture. M.tuberculosis, the slow grower takes 4 to 6 weeks on solid based medium. Thus various automated systems using liquid culture methods are useful for reducing detection time (between 9 to 16 days).Aim: To compare the liquid culture method by using Bact/Alert -3D automated culture system and conventional culture method from extrapulmonary specimens.Materials and Methods: The study was carried out in Department of Microbiology. Clinically suspected 66 samples were included in the study. Microscopy was done by Z-N staining .The samples were processed by standard guidelines. LJ medium were inoculated and incubated at 37°C. Sample was also inoculated in MP Bottle containing 7H9 Middlebrooks liquid Medium. LJ slopes were examined weekly for appearance of colony till 10 wks. MP bottles with positive results by Bact/Alert system were processed for identification and no growth up to 42 days was declared negative.Results: From 31.81% positive results for mycobacteria, 95.23% were detected positive by Bact/Alert while 28.57 % were positive by culture. Mean detection time of microscopy positive samples were detected in second week by Bactalert and in 4th week on LJ medium. Samples negative for microscopy, detected positive in fifth week by Bact/Alert-3D system while by seventh week on LJ medium.Conclusion: The sensitivity of liquid culture by automation is higher and earlier than culture on LJ Medium for detection of AFB which will help the patient for early clinical management. But cost is the main barrier in low economic setting.