Clonality of Mycobacterium ulcerans by Using VNTR-MIRU Typing in Ivory Coast (Côte d’Ivoire), West Africa

Background: Buruli ulcer (BU) is neglected skin disease caused by Mycobacterium ulcerans. The lack of early diagnosis and treatment causes severe disability. In Central and in West Africa, BU is endemic and its control is difficult because the most cases occur in rural regions. The molecular particularity of M. ulcerans was the acquisition of the virulence plasmid pMUM001. Genetic analyses have demonstrated the high diversity with variable number tandem repeats (VNTR) and Mycobacterial Interspersed Repetitive Units (MIRU) in M. ulcerans and in mycolactone producing Mycobacteria (MPMs).
Objective: The objective of this study was to investigate the molecular diversity by using MIRU-VNTR method in clinical samples of BU patients in Côte d’Ivoire.
Study Design: 21 clinical samples were collected from BU patients in different sites and were first analyzed in molecular diagnosis of BU using two targets insertion sequence IS2404 and keto reductase-B-domain (KR). In a second step, we have analyzed the strains by PCR typing for four specific and sensitive markers MIRU1, VNTR6, ST-1 and VNTR19.
Results and Conclusion: 100% of clinical samples were positive in molecular tests for IS2404 and 95% for KR and confirm M. ulcerans in the samples. By PCR typing, we have found 61.9 % positive for MIRU1 and 52%, 85.7%, and 61.9% for VNTR6, ST-1 and VNTR19 respectively. One of sample was negative for all genotyping markers. Two different genetic profiles were identified by MIRU1 and ST-1 loci by gel-analyzed of the amplified products. The VNTR profile C (3,1,1) corresponding of 3 copies MIRU1, 1 copy VNTR6 and 1 copy ST-1 was detected in 28.5% of samples and confirms the West African genotype in Côte d’Ivoire. Different genetic strains of M. ulcerans were co-circulated in the same endemic region in the country. This study has described first the circulating of different genetic strains of M. ulcerans in Côte d’Ivoire.