RESUMO
This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.
O objetivo deste trabalho foi estabelecer o potencial patogênico e a relação clonal de isolados de Aeromonas sp. e Vibrio cholerae obtidos durante um surto de diarréia. Isolados clínicos e ambientais foram investigados quanto à presença de genes de virulência e sua relação clonal foi obtida através de amplificação da Região Espaçadora Intergênica (REI) 16S-23S. Quatro genes de Aeromonas (lip, exu, gcat, flaA/B) foram encontrados em alta frequência embora o gene lip tenha se mostrado ausente em algumas espécies. Um quinto gene, aerA, foi raramente encontrado em A. caviae, a espécie mais abundante. O perfil da REI revelou alta heterogeneidade entre os isolados de Aeromonas e nenhuma correlação com espécie. Em contraste, todas as amostras de V. cholerae amplificaram os genes investigados (ctxA, tcpA, zot e ace) e revelaram perfil clonal através de REI e RAPD. Embora Aeromonas tenha sido o principal patógeno isolado, o perfil da REI não é compatível como única causa para os eventos de diarréia, enquanto a relação clonal de V. cholerae aponta esse microrganismo como o provável agente do surto. Estes resultados reforçam a necessidade de definir melhor o papel de Aeromonas em diarréias e de que forma essas bactérias se beneficiam quando em co-infecção com V. cholerae.
Assuntos
Humanos , Aeromonas/genética , Coinfecção/microbiologia , Surtos de Doenças , Diarreia/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Vibrio cholerae O1/genética , Aeromonas/patogenicidade , Brasil/epidemiologia , Coinfecção/epidemiologia , DNA Bacteriano/genética , Diarreia/epidemiologia , Genótipo , Infecções por Bactérias Gram-Negativas/epidemiologia , Reação em Cadeia da Polimerase , Técnica de Amplificação ao Acaso de DNA Polimórfico , Vibrio cholerae O1/patogenicidade , Virulência/genéticaRESUMO
This work aimed to assess pathogenic potential and clonal relatedness of Aeromonas sp. and Vibrio cholerae isolates recovered during a diarrhea outbreak in Brazil. Clinical and environmental isolates were investigated for the presence of known pathogenic genes and clonal relatedness was assessed by intergenic spacer region (ISR) 16S-23S amplification. Four Aeromonas genes (lip, exu, gcat, flaA/B) were found at high overall frequency in both clinical and environmental isolates although the lip gene was specifically absent from selected species. A fifth gene, aerA, was rarely found in A. caviae, the most abundant species. The ISR profile revealed high heterogeneity among the Aeromonas isolates and no correlation with species identification. In contrast, in all the V. cholerae isolates the four genes investigated (ctxA, tcpA, zot and ace) were amplified and revealed homogeneous ISR and RAPD profiles. Although Aeromonas isolates were the major enteric pathogen recovered, their ISR profiles are not compatible with a unique cause for the diarrhea events, while the clonal relationship clearly implicates V. cholerae in those cases from which it was isolated. These results reinforce the need for a better definition of the role of aeromonads in diarrhea and whether they benefit from co-infection with V. cholerae.
