*1,2Eliya, T. T., 1,2Ajide, B. A., 1Ugwu, C., 1Emmana, B., 1Ishaku, P., 1James, E., and 1,[1]John, B.
1Zankli Research Centre, Bingham University, Karu, Nasarawa State, Nigeria
2Biological Sciences Department, Bingham University, Karu, Nasarawa State, Nigeria
3Community Medicine and Primary Health Care Department, Bingham University, Karu, Nasarawa State, Nigeria *Correspondence to: iliya.taryuta@binghamuni.edu.ng; Tel: +2347034229746
Abstract:
Background: Tuberculosis (TB) culture is the ‘gold standard’ test for detecting Mycobacterium tuberculosis and enables comprehensive drug susceptibility testing. However, culture contamination remains a challenge in TB culture, resulting in significant loss of time and resources, and potentially leading to poor treatment outcomes due to incorrect clinical decision-making. The objective of this study is to assess the effect of sputum transit time on contamination rate and the yield of M. tuberculosis.
Methodology: We conducted a prospective analysis of all samples received for TB culture at a Reference Laboratory from January to December 2021. Samples were decontaminated by the standard N-Acetyl L-cysteine (NALC)/Sodium Hydroxide (NaOH) method and inoculated on Lowenstein-Jensen (LJ) solid media. The number of days from sample collection to processing was documented for all 988 valid samples received within the study period. A univariable analysis was used to explore the relationship between transit time and contamination rate. Percentages and Odds ratios with associated 95% confidence intervals were reported.
Results: Of 988 diagnoses and follow-up samples received, 508 (58.7%) were from males, while 14 (1.4%) were from children ≤ 14 years of age. Overall, 56 (5.7%) samples were contaminated, of which 17 (30.4%) were positive for AFB. A contamination rate of 4.1%, 7.1%, and 8.3% was recorded for Optimal (0-7 days), Delayed (8-14 days), and Extended delay (>15 days) samples, respectively. Compared to samples analyzed within optimal transit time, those with Delayed and Extended delay transit times had greater odds of being contaminated, with OR of 1.811 (95% CI=0.997-3.290) and 2.148 (95% CI=0.983-4.688), respectively.
Conclusion: The study revealed that TB culture contamination rate tends to increase with the number of days taken for sample movement from collection to processing. However, the association detected fell slightly short of achieving statistical significance. It is also instructive that about one in three contaminated samples were positive for AFB, which could have far-reaching implications for the clinical decision-making and management of persons being treated for various forms of TB. Investment in innovative approaches to ensure that all samples for TB culture reach the testing laboratories within the optimal period is likely to save time, resources, and lives.
Keywords: Mycobacterium tuberculosis, Tuberculosis-culture, contamination-rate, transit-time.
Download this Article in PDF format below