[Genotypic diversity of Mycobacterium tuberculosis in the Guiana-Antilles region]

This investigation dealt with 226 strains (1 isolate/patient) of Mycobacterium tuberculosis isolated in the French West Indies and French Guiana over a three-year period (1994-1996). The genotypic diversity of the isolates was investigated using various molecular markers; essentially two PCR-based rapid methods, namely spoligotyping and double-repetitive-element (DRE)-PCR, as well as three restriction fragment length polymorphism (RFLP)-based methods, namely IS6110-RFLP, DR-RFLP and PGRS-RFLP. Out of 226 isolates investigated, a total of 166 isolates were distributed in 31 spoligotype-defined clusters containing 2-31 strains, which corresponded to a rate of 73% of primary clustering. After secondary typing with DRE-PCR, IS6110-RFLP, DR-RFLP and/or PGRS-RFLP, molecular clonality was established for 73 isolates organised in 25 clusters (32% of clustered isolates). Considering one reactivation case per cluster, the rate of recent transmission was estimated to a minimal rate of 21%, however the available epidemiologic information led to the positive conclusion for only 14% of cases. The data obtained demonstrated the presence of common genotypes of M. tuberculosis among the three overseas French territories, i.e. Guadeloupe, Martinique and French Guiana. The results obtained during this retrospective study clearly indicate the importance of future prospective epidemiological investigations around the clustered cases of tuberculosis, so as to detect the persisting foci of endemic disease and characterize the chain of transmission as well as the subpopulations which are at an increased risk of contracting and/or propagating the disease. Last but not least, the present study also deals with a first phylogenetic approach of M. tuberculosis based on a comparison of the spoligotyping results obtained locally with those reported elsewhere in the world.