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

Fernanda Morcatti Coura,Soraia De Araújo Diniz,Jamili Maria Suhet Mussi,Marcos Bryan Heinemann,Marcos Xavier Silva,Andrey Pereira Lage,Camila Stefanie Fonseca De Oliveira,Cairo Henrique Sousa De Oliveira

doi:10.1590/0103-8478cr20180998

Abstract

ABSTRACT: This 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.

Highlights

Diarrhea is an important health concern in young animals, and frequently E. coli pathovars such as enterotoxigenic E. coli (ETEC), Shiga-toxin producing E. coli (STEC), enterohemorrhagic E. coli (EHEC), and entero-pathogenic E. coli (EPEC), are associated with its etiology (CROXEN & FINLAY 2010)
The identification of E. coli strains positive for EAST-1 (EAEC) was associated with the presence of diarrhea (P=0.008)
All seven phylogenetic groups were detected in E. coli isolated from diarrheic feces; phylogenetic groups A and F were identified at low frequency

Summary

Introduction

Diarrhea is an important health concern in young animals, and frequently E. coli pathovars such as enterotoxigenic E. coli (ETEC), Shiga-toxin producing E. coli (STEC), enterohemorrhagic E. coli (EHEC), and entero-pathogenic E. coli (EPEC), are associated with its etiology (CROXEN & FINLAY 2010). There are a few studies involving E. coli pathovar infections in buffalo calves worldwide (OLIVEIRA et al, 2007; BORRIELLO et al, 2012; MAHANTI et al, 2013; BERALDO et al, 2014). V.49, n.5, a heat stable toxin called EAST-1, primarily detected in strains of entero-aggregative E. coli (EAEC) strains, can occur in other pathovars such as ETEC, EPEC, and EHEC, and has been identified in strains of E. coli isolated from cattle and humans with diarrhea (NAGY & FEKETE, 2005; VEILLEUX & DUBREUIL, 2006); its ability to cause diarrhea in calves is less known (KOLENDA et al, 2015). Contamination with EHEC and STEC in dairy products from buffalo cows represents a potential risk to public health; the frequency of these pathovars in buffalos needs to be determined

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