Profile of non-tuberculous mycobacteria amongst tuberculosis presumptive people in Cameroon.

BACKGROUND: Cameroon is a tuberculosis (TB) burden country with a 12% positivity among TB presumptive cases. Of the presumptive cases with a negative TB test, some are infected with Non-tuberculous Mycobacteria (NTM). However, the diagnosis of NTM infections remains difficult due to the lack of tools in many laboratories, particularly in resource limited laboratories and remote setting. The present study was undertaken to determine NTM profile and associated comorbidities among TB presumptive people. METHODS: A retrospective study was conducted from December 2018 to December 2019 in the Tuberculosis-National Reference Laboratory (TB-NRL) for Bacteriological analysis of samples and Jamot Hospital of Yaounde (JHY) for clinical evaluation of confirmed NTM patients. We included in this study data of 5267 TB presumptive people previously diagnosed using three consecutive samples and having culture and SD Bioline results with or without Microscopy and reverse hybridization-based Line Probe Assay(LPA) results. The data on co-morbidities or history of people infected with NTM were then collected from the three participants with available clinical data. RESULTS: We collected data of 5267 presumptive TB people. Among them, 3436 (65.24%), have a positive culture with 3200 (60.75%) isolates belong to Mycobacterium tuberculosis Complex (MBTC) and 236 (4.48%) to NTM. Our results showed that, 123 (52.11%) NTM were isolated from people with negative microscopy and 113 (47.88%) from people with positive microscopy. Among the 236 NTM, 108 (45.8%) isolates were identified using LPA. M. fortuitum was the most represented species (32.41%) followed by M. intracellulare (19.44%). Sputum had the highest proportion of NTM (56%), followed by bronchial aspirations (31%). The extra-pulmonary samples presented lower proportions of isolates compared to pulmonary samples. Some patients affected with NTM presented comorbidities as HIV infection, Pulmonary tuberculosis, Type 2 diabetes, Chronic bronchitis and Alveolar pneumonia. CONCLUSIONS: Our study showed the presence of NTM strains among presumptive TB people with a predominance of M. fortuitum and M. intracellulare. It is important to implement a surveillance system of NTM in TB burden country and also to develop a point-of-care test for NTM identification in limited-resource settings.

A cost-benefit algorithm for rapid diagnosis of tuberculosis and rifampicin resistance detection during mass screening campaigns.

BACKGROUND: Active tuberculosis (TB) case finding is important as it helps detect pulmonary TB cases missed by the other active screening methods. It requires periodic mass screening in risk population groups such as prisoners and refugees. Unfortunately, in these risk population groups periodic mass screening can be challenging due to lengthy turnaround time (TAT), cost and implementation constraints. The aim of this study was to evaluate a diagnostic algorithm that can reduce the TAT and cost for TB and Rifampicin resistance (RR) detection. The algorithm involves testing with TB-LAMP followed by Xpert MTB/RIF for positive TB-LAMP cases to diagnose TB during mass campaigns in prisons and refugee camps. METHODS: The National Tuberculosis Control Program (NTCP) organized routine TB mass-screening campaigns in 34 prisons and 3 villages with refugees camps in Cameroon in 2019. TB LAMP was used for initial TB diagnosis and all TB-LAMP positive cases tested with the Xpert MTB/RIF assay to determine RR. TAT and cost benefits analysis of the combined use of TB-LAMP and Xpert MTB/RIF assays was determined and compared to the Xpert MTB/RIF assay when used only. RESULTS: A total of 4075 sputum samples were collected from TB presumptive, 3672 cases in 34 prisons and 403 samples in 3 villages. Of the 4,075 samples screened with TB-LAMP, 135 were TB positive (3.31%) and run on the Xpert MTB/RIF. Of the 135 positives cases, Xpert MTB/RIF revealed 3 were RR (2.22%). The use of TB-LAMP followed by testing with Xpert MTB/RIF for TB and RR detection reduced the TAT by 73.23% in prisons and 74.92% in villages. In addition to a reduced TAT, the two molecular tests used in synergy is cost benefit from year 2 onwards. CONCLUSION: This study demonstrates the advantages of a diagnostic algorithm based on an initial testing with TB-LAMP followed by testing with Xpert MTB/RIF for TB diagnosis. This approach improved early and rapid TB detection with an added advantage of providing RR status. The proposed algorithm is effective and less costly from the second year of implementation and should be used by TB control programs.

Diabetes mellitus and tuberculosis, a systematic review and meta-analysis with sensitivity analysis for studies comparable for confounders.

INTRODUCTION: Meta-analyses conducted so far on the association between diabetes mellitus (DM) and the tuberculosis (TB) development risk did not sufficiently take confounders into account in their estimates. The objective of this systematic review was to determine whether DM is associated with an increased risk of developing TB with a sensitivity analyses incorporating a wider range of confounders including age, gender, alcohol consumption, smoke exposure, and other comorbidities. METHODS: Pubmed, Embase, Web of Science and Global Index Medicus were queried from inception until October 2020. Without any restriction to time of study, geographical location, and DM and TB diagnosis approaches, all observational studies that presented data for associations between DM and TB were included. Studies with no abstract or complete text, duplicates, and studies with wrong designs (review, case report, case series, comment on an article, and editorial) or populations were excluded. The odds ratios (OR) and their 95% confidence intervals were estimated by a random-effect model. RESULTS: The electronic and manual searches yielded 12,796 articles of which 47 were used in our study (23 case control, 14 cross-sectional and 10 cohort studies) involving 503,760 cases (DM or TB patients) and 3,596,845 controls. The size of the combined effect of TB risk in the presence of DM was OR = 2.3, 95% CI = [2.0-2.7], I2 = 94.2%. This statistically significant association was maintained in cohort (OR = 2.0, CI 95% = [1.5-2.4], I2 = 94.3%), case control (OR = 2.4, CI 95% = [2.0-2.9], I2 = 93.0%) and cross-sectional studies (OR = 2.5, CI 95% = [1.8-3.5], I2 = 95.2%). The association between DM and TB was also maintained in the sensitivity analysis including only studies with similar proportions of confounders between cases and controls. The substantial heterogeneity observed was mainly explained by the differences between geographic regions. CONCLUSIONS: DM is associated with an increased risk of developing latent and active TB. To further explore the role of DM in the development of TB, more investigations of the biological mechanisms by which DM increases the risk of TB are needed. REVIEW REGISTRATION: PROSPERO, CRD42021216815.