[Vibrio cholerae in Madagascar: study of a multiresistant strain]

Madagascar was cholera free until March 1999. The first case was reported in Mahajanga, a north west coast harbor. Ten months later and despite a massive use of tetracycline as prophylactic drug, cholera had reached every region of the island. All suspected cholera samples were analysed at the Pasteur Institute of Madagascar where susceptibility to tetracycline was systematically performed. On February 2000, a multidrug resistant strain of V. cholerae was isolated. We studied this strain by performing Minimal Inhibitory Concentration (MIC) and by plasmidic and conjugative assay. As the original strain, this multiresistant V. cholerae showed a resistance to cotrimoxazole, to streptomycin and chloramphenicol but, in addition to, appeared strongly resistant to ampicillin and tetracycline. This strain harboured a 26 kb self-transmissible plasmid. Conjugation tests showed the possibility of plasmidic segregates or acquisition of two different plasmids. The weak transfer rate could explain why we have isolated only one multiresistant strain. The emergence of a such multiresistant strain should encourage the medical authorities to reinforce the epidemic survey in every medical Malagasy district and to carry out new antimicrobial surveys to describe the mechanisms of the spread of these resistances.