Abstract

BackgroundEnterococcus faecalis and Enterococcus faecium are ubiquitous opportunistic pathogens found in the guts of humans and farmed animals. This study aimed to determine the occurrence, antimicrobial resistance, virulence, biofilm-forming ability and genotypes of E. faecalis and E. faecium from swine farms. Correlations between the genotypes, virulotypes, antibiotic resistance, and the environmental factors such as locality of farms and farm hygiene practice were explored.MethodsE. faecalis and E. faecium strains were isolated from the oral, rectal and fecal samples of 140 pigs; nasal, urine and fecal samples of 34 farmers working in the farms and 42 environmental samples collected from seven swine farms located in Peninsular Malaysia. Antibiotic susceptibility test was performed using the disk diffusion method, and the antibiotic resistance and virulence genes were detected by Polymerase Chain Reaction. Repetitive Extragenic Palindromic-Polymerase Chain Reaction and Pulsed-Field Gel Electrophoresis were performed to determine the clonality of the strains. Crosstab/Chi-square test and DistLM statistical analyses methods were used to determine the correlations between the genotypes, virulence factors, antibiotic resistance, and the environmental factors.ResultsA total of 211 E. faecalis and 42 E. faecium were recovered from 140 pigs, 34 farmers and 42 environmental samples collected from seven swine farms in Peninsular Malaysia. Ninety-eight percent of the strains were multidrug-resistant (resistant to chloramphenicol, tetracycline, ciprofloxacin and erythromycin). Fifty-two percent of the strains formed biofilms. Virulence genes efa, asaI, gelE, esp, cyl and ace genes were detected. Virulence genes efa and asaI were most prevalent in E. faecalis (90%) and E. faecium (43%), respectively. Cluster analyses based on REP-PCR and PFGE showed the strains were genetically diverse. Overall, the strains isolated from pigs and farmers were distinct, except for three highly similar strains found in pigs and farmers. The strains were regional- and host-specific.DiscussionThis study revealed alarming high frequencies of multidrug-resistant enterococci in pigs and swine farmers. The presence of resistance and virulence genes and the ability to form biofilm further enhance the persistence and pathogenicity of the strains. Although the overall clonality of the strains were regionals and host-specific, strains with high similarity were found in different hosts. This study reiterates a need of a more stringent regulation to ensure the proper use of antibiotics in swine husbandry to reduce the wide spread of multidrug-resistant strains.

Highlights

  • Enterococci are Gram-positive facultative anaerobes and are part of microbiota of humans and animals (Lebreton, Willems & Gilmore, 2014; Kristich, Rice & Arias, 2014)

  • The objectives of the study were to determine the occurrence of MDR E. faecalis and E. faecium isolated from pigs, swine farmers and swine farm environment in Peninsular

  • All E. faecalis and E. faecium strains were confirmed with Polymerase Chain Reaction (PCR) targeting the sodA genes (Jackson, Fedorka-Cray & Barrett, 2004)

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Summary

Introduction

Enterococci are Gram-positive facultative anaerobes and are part of microbiota of humans and animals (Lebreton, Willems & Gilmore, 2014; Kristich, Rice & Arias, 2014). The emergence of MDR bacteria in the livestock industry is of public health concern as transmission of these bacteria to humans has been reported (Compassion in World Farming, 2011). The spread of such MDR strains can occur through direct (consumption of contaminated food, direct contact of farmers and veterinarians) or indirect (animal waste handling, contaminated ground water or surfaces) routes (Daniel et al, 2015). This study aimed to determine the occurrence, antimicrobial resistance, virulence, biofilm-forming ability and genotypes of E. faecalis and E. faecium from swine farms.

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