Effect of sputum characteristics, transportation time and HIV status on rapid detection of mycobacterium tuberculosis complex in resource limited settings

Abstract

Globally, Tuberculosis (TB) is one of the most devastating infectious diseases and its eradication is still a challenge given the limitations of the current diagnostic technologies and capacities. Sputum characteristics (appearance, volume), duration of transport and HIV status are recorded and reported to Clinicians, their effect on recovery of Mycobacterium tuberculosis complex was ignored. The current study was conducted to determine how Sputum characteristics, duration of transport and HIV status impact on the recovery of Mycobacteria species and technique for rapid detection. Sputum was collected from 145 patients and tested with Gene Xpert MTB/RIFTM, microscopy, and Culture which is the Gold standard. Positive cultures were confirmed using lateral flow device Capillia NeoTM, M. bovis and Line probe assay. Data was entered in Microsoft excel (Office program 2019) and analyzed using R-Studio version 3.5.2 for windows. Descriptive statistics were used for categorical data to determine demographic-based infection rate, Kaplan-Meier survival estimates of sample characteristic, comparison of the recovery time and identification tests were analyzed. The results showed that there is higher TB infection rate among male 63% (55-71, p=0.0016), age group 20-40 years 52% (44-61, p=0.6183), primary education 61% (52-69, p=0.1273) and HIV negative 66% (57-73, p=0.0002). The appearance, volume, duration of transport, and HIV status were significantly associated with time to detection of Mycobacterium tuberculosis complex using MGIT culture (P<0.05). The mean detection time for MGIT was 18 days (8-32), LJG 42 days (30-58) and LJP 38 days (28-52). MGIT recovery rate was 93.2% (82.7-97.8), LJP 84.7% (72.5-92.4) and LJG 83.1 (70.6-91.2). Sensitivity of Gene Xpert and Capillia NeoTM based on Culture was 98.3% (89.7-99.9), LPA test 89.8% (78.5-95.8), Microscopy 59.3% (45.8-71.7) and LFD M. bovis 26% (20.9-45.8). MGIT technique has shorter time to detection of mycobacteria; however after the conventional 42 days of incubation, 42% of mucopurulent samples and 32% of HIV+ would be reported as negative. Gene Xpert is the best identification test for the detection of MTC from clinical specimen with shorter turnaround time compared to Culture followed by LFD Capillia NeoTM. We recommend studies for Laboratories to extend MGIT culture duration to recover Mycobacteria from Mucopurulent and HIV+ patients.