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Published on: November 4, 2016
Resistome, Virulome, and Clonal Variation in Methicillin-Resistant Staphylococcus aureus (MRSA) in Healthy Swine
Vanessa Silva1,2,3,4, Adriana Silva1,2,3,4, Raquel Barbero5,6
1Associated Laboratory for Green Chemistry (LAQV-REQUIMTE), University NOVA of Lisboa, 2829-516 Caparica, Portugal.
Abstract:
This cross-sectional study investigates the methicillin-resistant Staphylococcus aureus (MRSA): its prevalence, antimicrobial resistance, and molecular characteristics in healthy swine populations in central Portugal. A total of 213 samples were collected from pigs on twelve farms, and MRSA prevalence was assessed using selective agar plates and confirmed via molecular methods. Antimicrobial susceptibility testing and whole genome sequencing (WGS) were performed to characterize resistance profiles and genetic determinants. Among the 107 MRSA-positive samples (83.1% prevalence), fattening pigs and breeding sows exhibited notably high carriage rates. The genome of 20 isolates revealed the predominance of the ST398 clonal complex, with diverse spa types identified. Antimicrobial susceptibility testing demonstrated resistance to multiple antimicrobial agents, including penicillin, cefoxitin, and tetracycline. WGS analysis identified a diverse array of resistance genes, highlighting the genetic basis of antimicrobial resistance. Moreover, virulence gene profiling revealed the presence of genes associated with pathogenicity. These findings underscore the significant prevalence of MRSA in swine populations and emphasize the need for enhanced surveillance and control measures to mitigate zoonotic transmission risks. Implementation of prudent antimicrobial use practices and targeted intervention strategies is essential to reducing MRSA prevalence and safeguarding public health. Continued research efforts are warranted to elucidate transmission dynamics and virulence potential, ultimately ensuring food safety and public health protection.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in Portuguese swine, with ST398 strains common. This highlights the need for better control measures to prevent spread and protect public health.
Area of Science:
- Veterinary Microbiology
- Food Safety
- Antimicrobial Resistance
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat to both animal and human health.
- Swine populations are recognized reservoirs for MRSA, with potential for zoonotic transmission.
- Understanding MRSA epidemiology in livestock is crucial for effective control strategies.
Purpose of the Study:
- To determine the prevalence, antimicrobial resistance, and molecular characteristics of MRSA in healthy swine in central Portugal.
- To identify specific MRSA strains and resistance genes circulating in the swine population.
- To assess the public health implications of MRSA carriage in pigs.
Main Methods:
- Cross-sectional study involving sample collection from 213 pigs across twelve farms in central Portugal.
- MRSA detection using selective agar and molecular confirmation.
- Antimicrobial susceptibility testing (AST) and whole genome sequencing (WGS) of MRSA isolates.
- Virulence gene profiling to assess pathogenicity potential.
Main Results:
- High MRSA prevalence (83.1%) was observed, particularly in fattening pigs and breeding sows.
- The ST398 clonal complex was predominant, with diverse spa types identified.
- Isolates showed resistance to multiple antimicrobials, including penicillin, cefoxitin, and tetracycline.
- WGS revealed various resistance and virulence genes, confirming the genetic basis of resistance and pathogenicity.
Conclusions:
- MRSA is widespread in Portuguese swine, with ST398 being a major clone.
- The findings highlight the urgent need for enhanced surveillance and control measures to mitigate zoonotic risks.
- Prudent antimicrobial use and targeted interventions are essential for reducing MRSA prevalence and safeguarding public health.
