Transferable plasmid-mediated resistance to streptomycin in a clinical isolate of Yersinia pestis

Plasmid-mediated high-level resistance to multiple antibiotics was reported in a clinical isolate of Yersinia pestis in Madagascar in 1997. We describ e a second Y. pestis strain with high-lever resistance to streptomycin, iso lated from a human case of bubonic plague in Madagascar. The resistance det erminants were carried by a self-transferable plasmid that could conjugate at high frequencies to other Y. pestis isolates. The plasmid and the host b acterium were different from these previously associated with multiple-drug resistance, indicating that acquisition of resistance plasmids is occurrin g in this bacterial species. Emergence of resistance to streptomycin in Y. pestis represents a critical public health problem since this antibiotic is used as the first-line treatment against plague in many countries.