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Staphylococcus aureus is More Prevalent in Retail Beef Livers than in Pork and other Beef Cuts
Lubna S Abdalrahman1, Harrington Wells2, Mohamed K Fakhr3
1Department of Biological Science, The University of Tulsa, Tulsa, OK 74104, USA. Lubna-abdalrahman@utulsa.edu.
Abstract:
Staphylococcus aureus is one of the top five pathogens contributing to acquired foodborne illnesses causing an estimated quarter million cases every year in the US. The objectives of this study were to determine the prevalence of Methicillin Susceptible S. aureus (MSSA) and Methicillin Resistant S. aureus (MRSA) in retail beef livers, beef, and pork meats sold in Tulsa, Oklahoma and to characterize the recovered strains for their virulence and antimicrobial resistance. Ninety six chilled retail beef (50 beef livers and 46 beef other cuts), and 99 pork meat samples were collected. The prevalence in beef livers was 40/50 (80%) followed by other beef cuts 23/46 (50%) then pork 43/99 (43.3%). No isolates were positive for MRSA since none harbored the mecA or mecC gene. A total of 334 recovered S. aureus isolates (143 beef livers, 76 beef, and 115 pork isolates) were screened for their antimicrobial susceptibility against 16 different antimicrobials and their possession of 18 different toxin genes. Multidrug resistance was more prevalent in the pork isolates followed by beef then beef livers. The prevalence of enterotoxin genes such as seg, seh, and sei and the toxic shock syndrome gene tst was higher in the pork isolates than in the beef ones. The hemolysin genes, particularly hlb, were more prevalent in isolates from beef livers. Molecular typing of a subset of the recovered isolates showed that they are highly diverse where spa typing was more discriminatory than PFGE. The alarmingly high incidence of S. aureus in retail beef livers in this study should raise awareness about the food safety of such meat products.
Insights
Staphylococcus aureus, a common cause of foodborne illness, was frequently found in retail meats, especially beef livers. While Methicillin-Resistant S. aureus (MRSA) was absent, multidrug-resistant strains and toxin genes were identified, highlighting food safety concerns.
Area of Science:
- Food Microbiology
- Food Safety
- Bacterial Pathogenesis
Background:
- Staphylococcus aureus is a leading cause of foodborne illness in the US.
- Understanding its prevalence and characteristics in retail meats is crucial for public health.
- Retail meat products, including beef livers, beef, and pork, are potential sources of S. aureus contamination.
Purpose of the Study:
- To determine the prevalence of Methicillin Susceptible S. aureus (MSSA) and Methicillin Resistant S. aureus (MRSA) in retail beef livers, beef, and pork.
- To characterize recovered S. aureus strains for virulence factors (toxin genes) and antimicrobial resistance.
- To assess the diversity of S. aureus isolates from different meat types.
Main Methods:
- Collection and microbiological analysis of retail beef liver, beef, and pork samples.
- Detection of mecA/mecC genes to identify MRSA.
- Antimicrobial susceptibility testing against 16 antimicrobials.
- Screening for 18 different toxin genes.
- Molecular typing using spa typing and pulsed-field gel electrophoresis (PFGE).
Main Results:
- High prevalence of S. aureus was observed in beef livers (80%), followed by other beef cuts (50%) and pork (43.3%).
- No MRSA isolates were detected; all identified strains were MSSA.
- Multidrug resistance was more common in pork isolates than beef or beef liver isolates.
- Specific toxin genes (seg, seh, sei, tst) were more prevalent in pork, while hemolysin genes (hlb) were more common in beef liver isolates.
- Molecular typing revealed high diversity among S. aureus isolates, with spa typing being more discriminatory than PFGE.
Conclusions:
- Retail beef livers show a high incidence of S. aureus contamination, necessitating increased food safety awareness.
- The presence of multidrug-resistant strains and virulence factors in S. aureus from retail meats poses a significant public health risk.
- Further research into control measures for S. aureus in meat production and processing is warranted.
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