Molecular epidemiology of drug resistant Mycobacterium tuberculosis in Africa: a systematic review

Abstract Background The burden of drug resistant tuberculosis (TB) in Africa is largely driven by the emergence and spread of multidrug resistant (MDR) and extensively drug resistant (XDR) Mycobacterium tuberculosis strains. The highest burden of drug resistant TB is seen in countries further experiencing an HIV epidemic, resulting in high HIV/TB co-morbidity rates. The molecular mechanisms of drug resistance as well as the evolution of drug resistant TB strains have been widely studied using various genotyping tools. Viewed as a whole, this can give a better insight into the transmission dynamics of drug resistant TB in Africa.Methods A systematic review was performed on peer reviewed original research extracted from PubMed reporting on the molecular epidemiology of drug resistant TB from African countries. The search terms “Tuberculosis AND drug resistance AND Africa AND (spoligotyping OR molecular epidemiology OR IS6110 OR MIRU OR DNA fingerprinting OR RFLP OR VNTR OR WGS)” were used to identify relevant articles reporting the molecular epidemiology of drug resistant TB in Africa. Only studies reporting on the molecular epidemiology of drug resistant TB in Africa were included in the analysis.Results Diverse genotypes are associated with drug resistant TB in Africa, with variations in strain predominance within the continent. It has been demonstrated that drug resistant TB strains are associated with community and nosocomial outbreaks. Outbreaks have been described both in immunocompromised and immunocompetent individuals, involving MDR- and XDR-TB strains. Furthermore, the role of migration in the transmission of drug resistant TB strains has been demonstrated in certain parts of Africa. Of concern is the under-use of molecular epidemiological tools, resulting in gaps in knowledge of the transmission dynamics of drug resistant TB on the continent.Conclusions Genetic diversity of M. tuberculosis strains has been demonstrated across Africa implying that diverse genotypes are driving the epidemiology of drug resistant TB across the continent. To address knowledge gaps, there is a need for routine surveillance and extensive epidemiological investigations across the continent.