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Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR (RS-PCR)
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Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR (RS-PCR)

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Prevalence, antimicrobial resistance, and molecular characterization of methicillin-resistant Staphylococcus aureus

K Kreausukon1, A Fetsch, B Kraushaar

  • 1Department Biological Safety, Federal Institute for Risk Assessment, 12277 Berlin, Germany.

Journal of Dairy Science
|July 24, 2012
PubMed

Insights

Methicillin-resistant Staphylococcus aureus (MRSA) was found in German dairy herds. These livestock-associated MRSA strains, belonging to CC398, exhibit antimicrobial resistance and carry hemolysin genes, similar to pig strains.

Area of Science:

  • Veterinary Microbiology
  • Food Safety
  • Antimicrobial Resistance

Background:

  • Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both human and animal health.
  • Livestock, particularly pigs, are known reservoirs for specific MRSA strains, including CC398.
  • The presence and characteristics of MRSA in dairy herds are crucial for understanding transmission dynamics and potential public health risks.

Purpose of the Study:

  • To determine the prevalence of MRSA in bulk tank milk from German dairy herds.
  • To characterize MRSA isolates for their Staph. aureus protein A (spa) type, staphylococcal cassette chromosome mec (SCCmec) type, antimicrobial resistance, and virulence-associated genes.

Main Methods:

  • A 2-step selective enrichment protocol was used to detect MRSA in 25 mL bulk tank milk samples.
  • Presumptive MRSA isolates were confirmed using Polymerase Chain Reaction (PCR).
  • Characterization involved broth microdilution and a microarray for MRSA, including spa typing and analysis of antimicrobial resistance and virulence genes.

Main Results:

  • All 36 characterized MRSA isolates from German dairy herds belonged to the clonal complex CC398.
  • High levels of resistance were observed for tetracycline (100%), clindamycin (58%), erythromycin (52%), quinupristin/dalfopristin (36%), and kanamycin (27%).
  • Isolates lacked Panton-Valentine leukocidin genes but carried hemolysin genes.

Conclusions:

  • Livestock-associated MRSA CC398 is present in German dairy herds.
  • The identified MRSA strains possess antimicrobial resistance profiles and virulence gene patterns similar to those found in MRSA from pigs.
  • These findings highlight the importance of monitoring MRSA in dairy production for animal and public health surveillance.

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