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Detection of bacteriocin production and virulence traits in vancomycin-resistant enterococci of different sources

C Sabia1, S de Niederhäusern, E Guerrieri

  • 1Department of Biomedical Sciences, University of Modena and Reggio E., Modena, Italy.

Journal of Applied Microbiology
|November 17, 2007
PubMed
Abstract

Insights

Vancomycin-resistant enterococci (VRE) persist in food, animal, and clinical samples, with many strains exhibiting antibacterial and virulence factors. Continuous monitoring of enterococci is crucial for assessing pathogenicity, especially for food industry and probiotic applications.

Area of Science:

  • Microbiology
  • Antimicrobial Resistance
  • Food Safety

Background:

  • Enterococci are common bacteria found in various environments, including food, animals, and clinical settings.
  • Vancomycin-resistant enterococci (VRE) pose a significant public health threat due to their resistance to a critical antibiotic.
  • Enterococci can possess virulence factors such as bacteriocin, cytolysin, haemolysin, and gelatinase production, contributing to their pathogenicity.

Purpose of the Study:

  • To evaluate the incidence of vancomycin-resistant enterococci (VRE) in food, animal, and clinical samples.
  • To assess the production of bacteriocin, cytolysin, haemolysin, and gelatinase in isolated enterococci.
  • To investigate the presence of specific genes associated with bacteriocin and virulence factors.

Main Methods:

  • Isolation and identification of 302 enterococcal strains from diverse sample types.
  • Detection of vancomycin resistance phenotypically.
  • Deferred antagonism method and polymerase chain reaction (PCR) to identify bacteriocin production and associated genes (enterocin A, enterocin P).
  • Assessment of virulence factors (gelatinase, haemolysin, cytolysin) and their corresponding genes (gelE, cylL(L)).

Main Results:

  • 27 (8.9%) of the isolates were identified as VRE.
  • 17 VRE isolates (63%) demonstrated bacteriocin production against Gram-positive and some Gram-negative bacteria.
  • PCR analysis confirmed the presence of enterocin A in six Enterococcus faecium strains and enterocin P in two Enterococcus faecalis strains.
  • Two VRE strains produced gelatinase, and seven were haemolytic. The gelE gene was found in 19 strains, and the cylL(L) gene in eight.
  • Only two E. faecalis strains with the cylL(L) gene expressed beta-haemolysis.

Conclusions:

  • VRE are prevalent in food, animal, and clinical environments, indicating their persistence.
  • A significant proportion of VRE isolates exhibit antimicrobial activity through bacteriocin production.
  • The presence of virulence factors in VRE strains highlights their potential pathogenicity and the need for careful consideration in food and probiotic applications.

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