Molecular epidemiology and genetic diversity of Mycobacterium tuberculosis complex in referral health centers of Bamako, Mali: What is new?

BACKGROUND AND AIMS: Tuberculosis (TB) remains an important global health issue worldwide. Despite this scourge threatening many human lives, especially in developing countries, thus far, no advanced molecular epidemiology study using recent and more accurate tools has been conducted in Mali. Therefore, this study aimed to use variable-number tandem repeats of mycobacterial interspersed repetitive units (MIRU-VNTR) technology coupled with the spoligotyping method to accurately determine the hot spots and establish the epidemiological transmission links of TB in Bamako, Mali. METHODS: In a cross-sectional study, 245 isolates of Mycobacterium tuberculosis complex (MTBC) were characterized using spoligotyping and MIRU-VNTR, and an epidemiological investigation was conducted. RESULTS: Of the 245 isolates, 184 (75.1%) were formally identified. The most widespread strain was the Cameroon strain (83; 45.1%). Eight major clusters were identified: Ghana (27; 14.7%), West African 2 (22; 12%), Haarlem (13; 7.1%), H37Rv (t) (8; 4.3%), Latin American Mediterranean (8; 4.3%), and Uganda I and II (6; 3.3%). Statistical analysis showed a significant difference between lineages from the respective referral health centers of Bamako, Mali (P = 0.01). CONCLUSION: This study establishes, for the first time, an accurate spatial distribution of circulating MTB strains in Bamako, Mali. The data was used to identify strains and "hot spots" causing TB infection and can also be used for more targeted public health responses, particularly for hot spots of drug-resistant strains.

Use of sodium dodecyl sulfate to improve tuberculosis sputum smear microscopy.

Sputum smear microscopy (SSM), the most widely available tool for tuberculosis (TB) detection, has limited performance in paucibacillary patients and requires highly experienced technicians. The objective of this study was to determine whether the addition of sodium dodecyl sulfate (SDS), a detergent that thins sputum, at 4% and 10%, improves the detection of acid-fast bacilli (AFB), the clarity of slides, and the biosafety of the technique. Thirty participants with presumptive TB were enrolled. Three independent, blinded technicians examined the slides. Regular sputum concentrated AFB smear and sputum culture were used as standard control methods. Sputum culture was also performed before and after 10% SDS addition for safety analysis. We found that neither SSM with SDS 4% nor SSM with SDS 10% improved the test's performance. However, slides with 4% and 10% SDS, compared with slides prepared without SDS, had significantly better clarity scores. The 10% SDS-prepared sputum samples were all culture negative. While adding SDS detergent does not improve the performance of SSM slides, it does improve the clarity and biosafety. Where experienced technicians are scarce, especially in low resource settings, use of SDS may enhance the ease of slide reading in sputum smear microscopy.

Diagnostic Performances of Three Rapid Diagnostic Tests for Detecting HIV Infections in Mali.

Diagnosis of HIV infections in resource-limited countries like Mali is based on Rapid Diagnostic Tests (RDTs). The RDTs are diagnostic assays designed for use at the Point-Of-Care (POC), which is quick, cost-effective and easy to perform. However, in these countries, the tests are commonly used without any initial evaluation or monitoring of their performance despite high levels of HIV strain diversity and rapid evolution of the virus. In this study, the reliability and accuracy of HIV RDTs (Determine™, Multispot™, SD Bioline™) used in Mali, where HIV-1 and HIV-2 co-exist, were evaluated from August 2004 to November 2017. A total of 1303 samples from new HIV-suspect patients in Bamako were tested for HIV-1 and HIV-2 using the RDT Determine™, followed by ELISA and Western Blot (WB). The Determine™ test showed a robust diagnostic sensitivity of 98.7% [CI 95: 97.59-99.37] and a diagnostic specificity of 99.2% [CI 95: 98.22-99.67]. The Multispot™ assay showed a diagnostic sensitivity of 98.77% [CI 95: 97.59-99.37] and a diagnostic specificity of 99.2% [CI 95: 98.22-99.67]. The diagnostic sensitivity and specificity of SD Bioline™ HIV-1/2 were 100% [CI 95:72.25-100] and 88.89% [CI 95: 56.50- 98.71], respectively. These data indicate excellent performance for HIV RDTs in Mali and we recommend the use of Determine™ HIV-1/2 for HIV screening and Multispot™ for discriminating HIV-2 from HIV-1 infections.