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<p>Cattle are the main reservoir of Shiga toxin-producing and atypical Enteropathogenic <i>Escherichia coli</i>. In this study, 159 STEC and 53 aEPEC isolates from dairy cattle were characterized for 41 and 30 virulence genes, respectively, including Shiga toxin subtypes, plasmid and O-islands-encoded genes. Furthermore, the isolates were characterised for <i>Escherichia coli</i> phylogroups antimicrobial resistance patterns. The majority of <i>stx1</i> and <i>stx2</i> positive STEC isolates carried <i>stx1a</i>,<i> stx1c</i>,<i> stx2c</i> and <i>stx2d</i> subtypes and plasmid-encoded genes <i>hlyA</i>, <i>espP</i> and <i>saa</i>. Most STEC isolates lacked OI-encoded genes including non-LEE-encoded effector genes. Most EPEC lacked plasmid-encoded genes but possessed OI-encoded genes and non-LEE effector genes such as <i>nleB</i>,<i> nleG2-3</i>,<i> nleG2-1</i>,<i> nleF</i>,<i> and nleH1-1</i>. The majority of virulence genes (≥ 23/41) were found in 11% (17/159) of STEC isolates which were <i>eaeA</i> positive and belonged to serotypes O26:H2, O26:H11, O136:H16, and O157:H7. At least 19% (10/53) of EPEC isolates that belonged to serotypes O26:H11, O177:H2, and O177:H11 carried most virulence genes (≥ 16/30). Most STEC (79.2%) and EPEC (62%) isolates were assigned to phylogroup B1. Antimicrobial resistance was observed in 13.2% and 35.9% of STEC and EPEC isolates, respectively. Furthermore, 3.8% of STEC and 7.6% of EPEC were multi-drug resistant. To our knowledge, this is the first study on the molecular characteristics of STEC and EPEC isolates from dairy cattle in South Africa. The findings of this study highlight the importance of dairy cattle as a reservoir and a probable source of virulent STEC and EPEC strains for humans in South Africa.</p>

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Virulence genes, antimicrobial resistance profiles and phylogroups of Shiga toxin-producing Escherichia coli and atypical enteropathogenic Escherichia coli isolates from dairy cattle in South Africa

  • 期刊论文

  • 发表日期：

    2025年11月19日

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  • Alaba Olawole,
  • Mogaugedi Malahlela,
  • Beniamino Cenci-Goga,
  • Luca Grispoldi,
  • Ernest Mokantla,
  • Musafiri Karama

摘要

Cattle are the main reservoir of Shiga toxin-producing and atypical Enteropathogenic Escherichia coli. In this study, 159 STEC and 53 aEPEC isolates from dairy cattle were characterized for 41 and 30 virulence genes, respectively, including Shiga toxin subtypes, plasmid and O-islands-encoded genes. Furthermore, the isolates were characterised for Escherichia coli phylogroups antimicrobial resistance patterns. The majority of stx1 and stx2 positive STEC isolates carried stx1a, stx1c, stx2c and stx2d subtypes and plasmid-encoded genes hlyA, espP and saa. Most STEC isolates lacked OI-encoded genes including non-LEE-encoded effector genes. Most EPEC lacked plasmid-encoded genes but possessed OI-encoded genes and non-LEE effector genes such as nleB, nleG2-3, nleG2-1, nleF, and nleH1-1. The majority of virulence genes (≥ 23/41) were found in 11% (17/159) of STEC isolates which were eaeA positive and belonged to serotypes O26:H2, O26:H11, O136:H16, and O157:H7. At least 19% (10/53) of EPEC isolates that belonged to serotypes O26:H11, O177:H2, and O177:H11 carried most virulence genes (≥ 16/30). Most STEC (79.2%) and EPEC (62%) isolates were assigned to phylogroup B1. Antimicrobial resistance was observed in 13.2% and 35.9% of STEC and EPEC isolates, respectively. Furthermore, 3.8% of STEC and 7.6% of EPEC were multi-drug resistant. To our knowledge, this is the first study on the molecular characteristics of STEC and EPEC isolates from dairy cattle in South Africa. The findings of this study highlight the importance of dairy cattle as a reservoir and a probable source of virulent STEC and EPEC strains for humans in South Africa.