Evaluation of factors influencing Mycobacterium tuberculosis complex recovery and contamination rates in MGIT960

Abstract Background Tuberculosis (TB) is a major public health problem worldwide. Contamination rate and poor recovery of Mycobacterium tuberculosis complex (MTBC) in MGIT960 culture may affect the early diagnosis of TB. Evidence is needed to determine the factors associated with contamination rates and MTBC recovery in MGIT960. Hence, we undertook this study to compare the factors influencing MTBC culture positivity and contamination rates in MGIT960 in patients with pulmonary tuberculosis (PTB). Methods A total of 849 sputum samples from newly diagnosed smear-positive TB cases enrolled into the RePORT India cohort between May2014 to March2017 were analysed. Samples were inoculated into MGIT960 and positive cultures were examined for the presence of MTBC by immunochromatographic test for detection of MPT64 antigen. Results Of the 849 cases, 811 (95.5%) were culture positive for MTBC, 23 (2.7%) were culture negative and 15 (1.8%) were contaminated. Salivary sputum showed significantly less culture yield compared to mucopurulent/blood stained samples (p=0.021). Sputum from individuals Conclusion Our results highlight that extremes of age, smear negativity, HIV infection, sputum quality and cavitation significantly influence the culture yield of MTBC, whereas transport duration and smear grading affected the contamination rates in MGIT960. Hence, addressing these factors may improve the diagnostic performance of MGIT960.