RESUMO
AIMS: The antagonistic activity of the Escherichia coli strain H22 against enteric bacteria was studied both in vitro and in vivo. METHODS AND RESULTS: In vitro, bacterial strains belonging to seven of nine genera of the family Enterobacteriaceae (Enterobacter, Escherichia, Klebsiella, Morganella, Salmonella, Shigella and Yersinia) were inhibited by the strain H22. Six days after simultaneous oral inoculation in germ-free mice, E. coli strain H22 reduced the faecal population of Shigella flexneri 4 to undetectable levels (P < 0.05). In ex vivo assay, inhibitory zones against Sh. flexneri 4 were observed around faecal samples from mice inoculated with E. coli strain H22. The in vitro inhibition of Sh. flexneri 4 was shown to be mediated by microcin C7. In addition to microcin C7, strain H22 was shown to produce aerobactin, new variants of colicins E1 and Ib, and bacteriophage particles with morphology similar to the phages of the family Myoviridae. CONCLUSIONS: Altogether, the properties of E. coli H22, observed both under in vitro and in vivo conditions, suggest its potential use as a probiotic strain for livestock and humans. SIGNIFICANCE AND IMPACT OF THE STUDY: The strain H22 was shown to produce several antimicrobial compounds with inhibitory capabilities against pathogenic or potentially pathogenic enterobacteria.
Assuntos
Enterobacteriaceae/fisiologia , Escherichia coli/fisiologia , Administração Oral , Animais , Antibacterianos/análise , Bacteriocinas/análise , Bacteriófagos/metabolismo , Colicinas/análise , Enterobacter/fisiologia , Escherichia/fisiologia , Fezes/microbiologia , Feminino , Ácidos Hidroxâmicos/análise , Klebsiella/fisiologia , Masculino , Camundongos , Microscopia Eletrônica/métodos , Morganella/fisiologia , Myoviridae , Plasmídeos/ultraestrutura , Salmonella/fisiologia , Shigella/fisiologia , Shigella flexneri/fisiologia , Sideróforos/análise , Yersinia/fisiologiaRESUMO
In order to detect phenotypic characteristics associated with pathogenicity, 25 strains of Escherichia coli, isolated from clinical cases of colisepticemia in broiler chickens, were examined to determine the following properties: colicinogenicity, colicin V production, type 1 fimbriae, hemolysin expression and motility. Colicinogenicity occurred in 72% of the strains, 56% of all strains produced colicin V, 84% were positive for type 1 fimbriae and 80% were positive for motility. None of the strains had hemolytic activity; however, all of them, expressed at least one of the other characteristics studied. These results suggest that the diversity of phenotypes detected partially explain the multifactorial nature of avian colisepticemia.
Assuntos
Infecções por Escherichia coli/veterinária , Escherichia coli/patogenicidade , Doenças das Aves Domésticas/microbiologia , Sepse/veterinária , Técnicas de Tipagem Bacteriana , Plasmídeos de Bacteriocinas , Técnicas Bacteriológicas , Colicinas/análise , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Fímbrias Bacterianas/ultraestrutura , Técnica de Placa Hemolítica , México , Fenótipo , Sepse/microbiologia , VirulênciaRESUMO
In order to detect phenotypic characteristics associated with pathogenicity, 25 strains of Escherichia coli, isolated from clinical cases of colisepticemia in broiler chickens, were examined to determine the following properties: colicinogenicity, colicin V production, type 1 fimbriae, hemolysin expression and motility. Colicinogenicity occurred in 72 of the strains, 56 of all strains produced colicin V, 84 were positive for type 1 fimbriae and 80 were positive for motility. None of the strains had hemolytic activity; however, all of them, expressed at least one of the other characteristics studied. These results suggest that the diversity of phenotypes detected partially explain the multifactorial nature of avian colisepticemia.(AU)
Assuntos
Escherichia coli/patogenicidade , Infecções por Escherichia coli/veterinária , Doenças das Aves Domésticas/microbiologia , Sepse/veterinária , Técnicas de Tipagem Bacteriana , Técnicas Bacteriológicas , Plasmídeos de Bacteriocinas , Colicinas/análise , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Fímbrias Bacterianas/ultraestrutura , Técnica de Placa Hemolítica , México , Fenótipo , Sepse/microbiologia , VirulênciaRESUMO
Colicin production was studied among 137 Escherichia coli strains isolated from pregnant patients with symptomatic or asymptomatic, urinary tract infection (IVU). The observed colicinogeny frequency was 72.92% (n = 96), among the symptomatic patients and 29.26% (n = 41) among the asymptomatic group. The most frequently identified colicins from symptomatic patients were: V (23.9%), A (18.7%) and E1 (17.7%) and within the patients with asymptomatic IVU the most frequently observed colicins were A (9.7%), E1 (17.0%) y V (2.4%). The major frequency of colicin V among the E. coli strains isolated from the symptomatic group against the asymptomatic one, was statistical significant (p > or = 0.025). The results on the observed frequencies of colicins E1 and A were not statistical significant. Among the 137 studied E. coli strains, 37.2% were hemolytic. 83.3% of the colicin V producing strains (n = 24) were hemolytic, among the strains producing other colicin different than colicin V 34% (n = 58) were hemolytic and 12.0% of non colicinogenic strains were hemolytic. These results were statistical significant (p > 0.05). The present data, suggest that colicins production is an important pathogenicity factor among the E. coli strains, specially for those strains producing colicin V. The observed association among hemolysin and colicin V production may be an interesting pathogenicity factor which suggests an increasing ability of uropathogenic strains to produce symptomatic urinary tract infections.
Assuntos
Colicinas/análise , Infecções por Escherichia coli/microbiologia , Escherichia coli/metabolismo , Proteínas Hemolisinas/análise , Complicações Infecciosas na Gravidez/microbiologia , Infecções Urinárias/microbiologia , Feminino , Humanos , GravidezRESUMO
30 strains isolated from clinical cases and a laboratory induced R-mutant or S typhi were studied. The synthesis of Colicin V, Siderophores, hydroxamate and phenolate (Aerobactin and Enterochelin) were investigated using biological assays. All strains were positive for Enterochelin but only strains 6586 and 4448 were positive for Aerobactin. An 80 kD receptor for enterochelin was found in the outer membrane of strains. Only strains 4448, 635 and 4693 produced Colicin V. Plasmid related antibiotic resistance was demonstrated in 7 strains and was considered "cryptic" in 3 others. The LD50 for mice ranged from 2.7 x 10(4) to 1 x 10(9) bacteria per ml. The presence of pathogenic factors was not related to the LD50.