Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) isolates of swine origin form robust biofilms

PLoS One. 2013 Aug 9;8(8):e73376. doi: 10.1371/journal.pone.0073376. eCollection 2013.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) colonization of livestock animals is common and prevalence rates for pigs have been reported to be as high as 49%. Mechanisms contributing to the persistent carriage and high prevalence rates of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) strains in swine herds and production facilities have not been investigated. One explanation for the high prevalence of MRSA in swine herds is the ability of these organisms to exist as biofilms. In this report, the ability of swine LA-MRSA strains, including ST398, ST9, and ST5, to form biofilms was quantified and compared to several swine and human isolates. The contribution of known biofilm matrix components, polysaccharides, proteins and extracellular DNA (eDNA), was tested in all strains as well. All MRSA swine isolates formed robust biofilms similar to human clinical isolates. The addition of Dispersin B had no inhibitory effect on swine MRSA isolates when added at the initiation of biofilm growth or after pre-established mature biofilms formed. In contrast, the addition of proteinase K inhibited biofilm formation in all strains when added at the initiation of biofilm growth and was able to disperse pre-established mature biofilms. Of the LA-MRSA strains tested, we found ST398 strains to be the most sensitive to both inhibition of biofilm formation and dispersal of pre-formed biofilms by DNaseI. Collectively, these findings provide a critical first step in designing strategies to control or eliminate MRSA in swine herds.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / pharmacology
  • Biofilms / drug effects*
  • Biofilms / growth & development
  • Endopeptidase K / pharmacology*
  • Glycoside Hydrolases / pharmacology
  • Humans
  • Livestock / microbiology*
  • Methicillin-Resistant Staphylococcus aureus / drug effects*
  • Methicillin-Resistant Staphylococcus aureus / growth & development
  • Methicillin-Resistant Staphylococcus aureus / isolation & purification
  • Microbial Sensitivity Tests
  • Staphylococcal Infections / drug therapy
  • Staphylococcal Infections / microbiology
  • Staphylococcal Infections / veterinary*
  • Swine
  • Swine Diseases / drug therapy
  • Swine Diseases / microbiology*

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Glycoside Hydrolases
  • dispersin B, Actinobacillus actinomycetemcomitans
  • Endopeptidase K

Grants and funding

This research was funded in its entirety by congressionally appropriated funds to the U.S. Department of Agriculture, Agriculture Research Service. The funders of the work did not influence study design, data collection and analysis, decision to publish, and preparation of the manuscript.