Occurrence of hybrid Escherichia coli strains carrying Shiga toxin and heat-stable toxin in livestock of Bangladesh

Fatema Tuz Johura, Rozina Parveen, Atiqul Islam, Abdus Sadique, Md Niaz Rahim, Shirajum Monira, Anisur R. Khan, Sunjukta Ahsan, Makoto Ohnishi, Haruo Watanabe, Subhra Chakraborty, Christine M. George, Alejandro Cravioto, Armando Navarro, Badrul Hasan, Munirul Alam

Research output: Contribution to journalArticlepeer-review

Abstract

Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC) are important causes of diarrhea in humans and animals worldwide. Although ruminant animals are the main source of STEC, diarrhea due to this pathotype is very low in Bangladesh where ETEC remains the predominant group associated with childhood diarrhea. In the present study, E. coli strains (n = 35) isolated from Bangladesh livestock (goats, sheep, and cattle) and poultry (chicken and ducks) were analyzed for the presence of major virulence factors, such as Shiga toxins (STX-1 and STX-2), heat-labile toxin, and heat-stable toxins (STa and STb). Multiplex polymerase chain reaction results revealed 23 (66%) E. coli strains to be virulent possessing either sta (n = 5), stx (stx1, n = 8; stx2, n = 2), or both (n = 8) genes in varying combinations. Thirty-four percent (8/23) of strains from livestock were hybrid type that carried both stx (either stx1 or stx2) and ETEC-specific enterotoxin gene sta. Serotyping results revealed that the ETEC strains belonged to five serotypes, namely O36:H5, O174:H-, O152:H8, O109:H51, and O8:H21, while the STEC-producing strains belonged to serotypes O76:H19 (n = 3), O43:H2 (n = 2), O87:H16 (n = 2), OR:H2 (n = 1), O110:H16 (n = 1), and O152:H8 (n = 1). The STEC-ETEC hybrid strains belonged to serotypes O76:H19 (n = 3), O43:H2 (n = 2), O87:H16, OR:H2, and O152:H8. Forty percent (2/5) of the ETEC and 20% (2/10) of the STEC strains were multidrug resistant with the highest drug resistance (50%) being found in the hybrid strains. Molecular fingerprinting determined by pulsed-field gel electrophoresis and cluster analyses by dendrogram revealed that, genetically, STEC-ETEC hybrid strains were highly heterogeneous. Multidrug-resistant E. coli STEC-ETEC hybrid strains in domesticated animals pose a public health threat for humans in Bangladesh.

Original languageEnglish (US)
Article number287
JournalFrontiers in Public Health
Volume4
Issue numberJAN
DOIs
StatePublished - Jan 9 2017

Keywords

  • Enterotoxin
  • Hybrid
  • Livestock
  • Multidrug resistant
  • PFGE
  • Shiga-toxin

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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