Caracterização molecular de Escherichia coli isoladas de bovinos, bubalinos e aves

Abstract

Escherichia coli pathotypes are important enteropathogens involved in the diarrheal syndrome. Pathogenic E. coli are classified into pathotypes according to the production of virulence factors and mechanisms which they cause the disease. Five pathotypes have been identified associated E. coli diarrhea in calves: enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), Shiga toxin-producing E. coli (STEC) and necrotoxigenic E. coli (NTEC). In this study, E. coli strains isolated from feces of cattle and buffalo calves and poultry carcasses were studied. Phylogenetic analysis of the 336 strains of E. coli isolated from bovine calves showed that 21 (6.25%) belonged to phylogroup A, 228 (67.85%) to phylogroup B1, 2 (0.6%) to phylogroup B2, 5 (1.49%) to phylogroup C, 57 (16.96%) to phylogroup E and 3 (0.9%) the filogrupo F. Phylogroup D was identified and twenty samples (5.95%) were designated as phylogroup "unknown". Only ETEC was associated with the presence of diarrhea (P = 0.002) and there was no association between the phylogenetic group of E. coli and the presence of diarrhea (P = 0.164). The correspondence analysis showed that EHEC and STEC are classified primarily as phylogroup B1.EAEC (EAST-1) phylogroup A, ETEC and EPEC phylogroup E. In total, 217 E. coli strains were isolated from feces of buffalo calves. Pathotypes identified in diarrheic feces were ETEC (2/84), NTEC (16/84), STEC (20/84), EPEC (3/84), EHEC (3/84) and EAEC (33/84). In non-diarrheic feces the pathotypes identified were NTEC (21/50), STEC (17/50), EHEC (1/50) and EAEC (7/50). Feces from animals aged 1 to 30 days were more frequently positive for E. coli virulence factors. Pathotype EAEC (EAST-1) (P = 0.008) and phylogroup C (P = 0.03) were associated with the presence of diarrhea. The analysis of E. coli phylogroup showed that 58.95% were phylogroup B1, followed by phylogroup s E (9.70%), B2 (5.9%), C (5.9%), D (5.22%), A (2.24%) and F (1.50%). E. coli strains isolated from poultry carcasses with normal appearance and carcasses condemned of colibacillosis in a slaughterhouse with Federal Inspection Service in the state of Tocantins were analyzed. One hundred and thirty seven samples of E. coli were obtained after isolation and biochemical identification. Eighty-four samples of E. coli were isolated from broiler carcasses condemned, of which 11 were isolated from the heart, 7 from the liver and 66 from the respiratory tract. Of the 53 strains isolated from normal poultry carcasses, 5 were isolated from heart, 4 from liver and 44 from the respiratory tract. The phylogroups A followed byB1 were the most common E.coli phylogroups isolated from healthy broiler carcasses, while phylogroups B1 followed by the A were more common in broiler carcasses condemned. The phylogroups B2, C, D, E and F were the least common phylogroups. The distribution of phylogenetic groups of 529 E. coli strains isolated from the three animal species were studied The frequency of phylogroups was: A = 15.31%, 60.49% = B1, B2 = 2.46%, C = 4.35%, D = 2.46%, 12.29% and E = F = 2.64%. The phylogroups A (P 0.001) and F (p = 0.002) were associated with E. coli isolated from poultry, phylogroups B1 (P 0.001) and E (P 0.001) with E. coli isolated from cattle and phylogroups B2 (P 0.001) and D (P = 0.007) with E. coli isolated from buffalo. The results demonstrate that some phylogroups ofE. coli are associated with the host studied and allow a better understanding of the phylogenetic composition of E. coli isolated fromin domestic animals