VARIABLE NUMBER TANDEM REPEAT TYPING OF NON-TUBERCULOUS MYCOBACTERIA ISOLATES IN HUMANS AND ENVIRONMENTS SAMPLES; TRANSMISSION STUDIES IN A BURULI ULCER ENDEMIC DISTRICT IN THE ASHANTI REGION, GHANA.

Non-Tuberculous Mycobacteria (NTM) also known as Environmental Mycobacteria (EM) are opportunistic and ubiquitous mycobacteria. Their mode of transmission appears to be dependent on the close proximity of humans with contaminated environments. One subset of NTMs, the Mycolactone Producing Mycobacteria (MPM); Mycobacterium pseudoshottsii, Mycobacterium liflandii, Mycobacterium xenopi and Mycobacterium ulcerans (MU), are of immense importance because of their pathogenicity in causing debilitating ulcers in both animals and man. Possible transmission routes will involve the interplay of the environment and humans.
This study aimed to determine and compare strain distribution of selected NTMs (focus on Mycobacterium ulcerans) from selected MU-infected environments and humans within four Buruli ulcer (BU) endemic communities in Ghana. Environmental samples (N=140) including biofilms, soil, detritus and water filtrates were obtained from 10 water bodies within four study areas. Following screening for Mycobacterium spp and MPMs using primers detecting the mycobacterial 16S rRNA and IS2404 genes, MU VNTR loci; locus 6, locus 19, ST1 and MIRU1, were used to genotype human (n=14) and environmental (n=20) isolates. Length polymorphism was validated using a reference strain, M. marinum DL and sequencing.
Twenty-seven percent (27%) of samples, mostly biofilms, from 9 water bodies were positive for Mycobacterium spp, of which 65.8% were MPMs, mostly M. ulcerans. Four MU genotypes, designated, W, X, Y and Z, which represented human isolates, matched those obtained in the environment, suggesting water bodies as major sources of infection. Additionally, previously
reported genotypes, A and B (MU), MLF (Mycobacterium liflandii) and MMDL (Mycobacterium marinum DL) were found only in water bodies. Genetic comparisons showed that for each community, at least one MU genotype is found both in humans and water bodies within it.
Genotype Y was shared by all human and environmental isolates from all four communities, suggesting wide dissemination within the Offin River. All repeats were confirmed with sequencing and phylogenetic analysis clustered isolates in this study with reference MU sequences from GenBank.
These findings support the hypothesis that transmission of NTMs, particularly MU, is dependent on the overlapping habitats of the pathogen and man. Further, it showed VNTR typing as a comparably useful tool for differentiating MU strains in BU endemic communities.