MOLECULAR CHARACTERIZATION OF VIBRIO-CHOLERAE O1 STRAINS ISOLATED DURING CHOLERA OUTBREAKS IN GUINEA-BISSAU

In the present study, 19 strains of Vibrio cholerae O1 biotype El Tor isolated during outbreaks of cholera in Guinea Bissau in 1987, 1994, a nd 1995 were characterized to investigate a possible epidemiological r elationship among the isolates. On the basis of ribotyping with the re striction enzyme BglI, 5 strains isolated in 1987 showed two closely r elated ribotypes, while 14 strains isolated in 1994 and 1995 showed th e same ribotype that was distinct from the ribotypes of strains isolat ed in 1987, Southern blot hybridization of BglI-digested genomic DNA w ith a cholera toxin probe demonstrated that the strains isolated in 19 87 shelved an identical cholera toxin genotype, whereas O1 strains iso lated in 1994 and 1995 showed the same genotype that was distinct from the genotype of strains isolated in 1987, These results were supporte d by the results of antibiotic susceptibility testing, in which strain s isolated in 1987 showed resistance to polymyxin B only, while each o f the strains from 1994 and 1995 showed resistance to polymyxin B, tri methoprim-sulfamethoxazole, and the vibriostatic agent O/129, Although our results are based on a limited number of V. cholerae O1 strains, they suggest that the epidemic in Guinea-Bissau in 1994 and 1995 was d ue to the introduction of a new strain to the country.