Enterohemorrhagic Escherichia coli O157: H7 from healthy dairy cattle in Mid-West Brazil: occurrence and molecular characterization

Abstract

Pesq. Vet. Bras. 34(1):24-28, janeiro 2014 24 RESUMO.-[Escherichia coli enterohemorrágica O157: H7 em bovinos leiteiros saudáveis no Centro-Oeste do Brasil: ocorrência e caracterização molecular.] Escherichia coli enterohemorrágica (EHEC) sorotipo O157:H7 representa as principais cepas de E. coli produtoras de toxina Shiga (STEC) relatadas em grandes surtos e doenças graves, tais como colite hemorrágica (CH) e síndrome hemolí-tica urêmica (SHU), potencialmente letais. O objetivo deste estudo foi reportar a ocorrência e caracterização molecular de STEC 0157:H7 isoladas por swab retal de 52 bovinos saudáveis pertencentes a 21 rebanhos leiteiros do Centro--Oeste do Brasil. A detecção dos genes 16SrRNA, stx1, stx2, rfbO157, fliCh7, eae, ehxA, saa, cnf1, chuA, yjaA Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 represents the major Shiga toxin-producing E. coli (STEC) strain related to large outbreaks and severe diseases such as hemorrhagic colitis (HC) and the potentially lethal hemolytic uremic syndrome (HUS). The aim of this study was to report the occurrence and molecular characterization of O157:H7 isolates obtained by rectal swab from 52 healthy dairy cattle belonging to 21 farms in Mid-West of Brazil. Detection of 16SrRNA, stx1, stx2, rfbO157, fliCh7, eae, ehxA, saa, cnf1, chuA, yjaA and TSPE4.C2 genes was performed by PCR. The isolates were further characterized by serotyping. Two hundred and sixty E. coli isolates were obtained, of which 126 were characterized as STEC. Two isolates from the same cow were identified as serotype O157:H7. Both isolates presented the stx2, eae, ehxA, saa and cnf1 virulence factor genes and the chuA gene in the phylogenetic classification (virulent group D), suggesting that they were clones. The prevalence of O157:H7 was found to be 1.92% (1/52 animals), demonstrating that healthy dairy cattle from farms in the Mid-West of Brazil are an important reservoir for highly pathogenic E. coli O157:H7.

Detection of virulence factors and antimicrobial resistance patterns in shiga toxin-producing Escherichia coli isolates from sheep

“…Studies by Ferreira et al (2014) and Freitas-Filho et al (2014) were pioneering in determining the prevalence of STEC and STEC/O157:H7 in healthy cattle in the State of Goiás, Brazil, while our study evaluated the virulence factors and antimicrobial resistance in STEC isolates obtained from healthy sheep in this State. On the contrary, Blanco et al (2003) found a higher prevalence of non-O157 STEC in sheep compared to cattle, where our study did not reveal the difference between sheep (78.3%) and cattle (72.7%) .…”

Occurrence of Virulence Genes and Antimicrobial Resistance of E. coli O157:H7 Isolated from the Beef Carcass of Bahir Dar City, Ethiopia

“…The enterohemorrhagic hemolysin hlyA makes adherence possible for eae -negative strains. When both hlyA and eae genes are present, this is an indicator for increased pathogenicity [ 10 ]. In addition, 20% of the isolates harbored the eae gene in our study.…”

“…Shiga toxins are a family of related toxins with two major groups, Shiga toxin 1 ( stx1 ) and Shiga toxin 2 ( stx2 ), expressed by genes considered to be horizontally acquired by bacteriophages, and are encoded by stx1 and stx2 genes, respectively [ 5 , 8 ]. In addition, enterohemolysin [ 9 ] and intimin [ 10 ], encoded by hlyA and eae genes, respectively, are another form of virulence factors of the bacteria [ 7 ].…”

Shiga toxin‐producingEscherichia coliin the animal reservoir and food in Brazil

“…STEC frequencies in cattle ranging from 16·5 to 78·3% were reported from the Midwest region (Salvadori et al ; Ferreira et al , ) with the detection of serotypes O26:NM, O111:NM, O118:H14 and O118:H16 in eae ‐positive strains. In the Goiás State (GO), Freitas‐Filho et al () described a prevalence of 1·9% of O157:H7 STEC strains among healthy dairy calves and Santos et al () isolated the O26 and O113:H21 STEC strains in cattle at slaughterhouse in the Mato Grosso State (MT). Only few reports from swine are available.…”

“…The O157:H7 STEC isolates from Brazil and other Latin American countries share several phenotypic and genotypic characteristics and the analysis of their genetic relatedness suggested the presence of a particular clone more related to human infections in Brazil, as well as a common origin for some strains isolated from different sources and countries (Guth et al ; Bastos et al ; Regua‐Mangia et al ; Freitas‐Filho et al ). Some Brazilian O157 strains isolated from cattle did not express Stx, including the strains isolated by Cerqueira et al (), while all Brazilian strains recovered from human disease do.…”