Virulence factors and phylotyping of Escherichia coli isolated from non-diarrheic and diarrheic water buffalo calves

EnglishThis study aimed to determine the virulence factors, phylogenetic groups, and the relationships between pathovars and phylogenetic groups of E. coli strains isolated from feces of buffalo calves. A total of 217 E. coli strains were obtained from feces after culture and were screened by PCR for detection of virulence factors EAST-1, enterohemolysin, Saa, CNF2, F41, F5, STa, intimin, Stx1 and Stx2. One hundred and thirty-four isolates were positive for one or more virulence factors: eighty-four from diarrheic animals, and fifty from non-diarrheic calves. The pathovars of E. coli identified in diarrheic feces were ETEC (F5+) (2/84), NTEC (16/84), STEC (20/84), EPEC (3/84), EHEC (3/84), and EAEC (EAST-1+) (33/84). Pathovars identified in non-diarrheic animals were NTEC (21/50), STEC (17/50), EHEC (1/50) and EAEC (7/50). E. coli strains positive for EAST-1 (P=0.008) and phylogroup C (P = 0.05) were associated with the presence of diarrhea. Phylogenetic analysis showed that 58.95% of the isolates belonged to phylogroup B1, followed by E (9.70%), B2 (5.90%), C (5.90%), D (5.22%), A (2.24%), and F (1.50%). Phylogroup B1 predominated in pathogenic E. coli isolated from water buffalo, and phylogroup C constituted an enteropathogenic E. coli for water buffalo calves. Key words: buffalo calves; diarrhea; Escherichia coli; pathovars; phylogenetic group portuguesO objetivo foi determinar os fatores de virulencia, os grupos filogeneticos e as possiveis relacoes entre os patovares e os grupos filogeneticos identificados de cepas de Escherichia coli isoladas de fezes de bezerros bubalinos. Um total de 217 amostras de E. coli foram identificadas a partir de cultura das fezes e submetidas a reacao em cadeia da polimerase (PCR) para deteccao dos fatores de virulencia EAST-1, enterohemolisina, Saa, CNF2, F41, F5, STa, intimina, Stx1 e Stx2. Foram identificadas 134 cepas positivas para um ou mais fatores de virulencia: 84isoladas de bezerros bubalinos diarreicos e 50 de bezerros bubalinos saudaveis. Os patovares de E. coli obtidos de fezes diarreicas foram ETEC (F5+) (2/84), NTEC (16/84), STEC (20/84), EPEC (3/84), EHEC (3/84), e EAEC (EAST-1+) (33/84). Os patovares isolados de fezes nao diarreicas foram NTEC (21/50), STEC (17/50), EHEC (1/50) e EAEC (7/50). Cepas de E. coli positivas para EAST-1 (P = 0,008) e filogrupo C (P = 0,05) foram associadas com a presenca de diarreia. A analise de filogrupos revelou que 58,95% dos isolados pertencem ao filogrupo B1, seguido por E (9,70%), B2 (5,90%), C (5,90%), D (5,22%), A (2,24%) e F (1,50%). O filogrupo B1 predomina em cepas de E. coli patogenicas isoladas de bezerros bufalos e o filogrupo C constitui um filogrupo de E. coli patogenica enterica para bezerros. Palavras-chave: bezerros bubalinos; dirreia, Escherichia coli;,grupo filogenetico, patovares