Caracterização molecular de Vibrio cholerae O1 sacarose negativa de isolados clínicos e ambiente na Amazônia brasileira

Abstract

The V. cholerae is an autochthonous organism of the aquatic environment and serogroups O1 and 139 are associated to the pandemic and epidemic cholera. The V. cholerae non-O1 and non O139 or non-binders vibrios (NAGS) are involved in isolated cases and outbreaks of cholera-like diarrhea. During the seventh pandemic there was the emergence of several isolated “El Tor atypical”. Among these there is a biochemical variant of V. cholerae O1 that does not ferment sucrose in TCBS in 18 to 24 hours which is the conventional incubation time. In this work, we studied 138 isolates of V. cholerae O1 and non O1 non-fermenter of sucrose on TCBS from clinical and environmental origin, obtained between 1994 and 1995 in the Brazilian Amazon (states of Pará, Amapá and Amazonas). We evaluated the fermentation of sucrose in TCBS and broth; the susceptibility to eight different antimicrobials in agar diffusion, the clonal relationship between V. cholerae O1 and NAG from clinical and environmental origin by PFGE and the presence of virulence genes tcpA and ctxAB by the polymerase chain reaction. It was observed that the samples of V. cholerae did not ferment sucrose in 24 hours of incubation in TCBS agar and broth, 43% used sucrose in 24 hours and 57% fermented it lately (more than 24 hours). The isolates had a low percentage of antimicrobial resistance (8.7%) and no cases of multidrug resistance. Regarding the virulence genes, in general, the isolates of V. cholerae O1 showed the ctxAB and tcpA. In the non-O1, these were absent, except for one clinical isolate non-O1 (gene tcpA +). The PFGE analysis revealed pulsotypes distinguished between O1 and nags, although two of the latter had presented the clonal relationship to clinical O1. All O1 clinical isolates were clonally related to the reference isolates from the seventh pandemic.