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Updated: Feb 19, 2026
Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR RS-PCR
Published on: November 4, 2016
Closely related methicillin-resistant Staphylococcus aureus isolates from retail meat, cows with mastitis, and humans
Tomomi Sato1, Masaru Usui1, Noriko Konishi2
1Laboratory of Food Microbiology and Food Safety, Department of Health and Environmental Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
Abstract:
Methicillin-resistant Staphylococcus aureus (MRSA) is a pervasive healthcare-acquired (HA) pathogen with recent emergence as a community-acquired (CA) pathogen. To elucidate whether meat mediates MRSA transmission between animals and humans in Japan, this study examined MRSA isolates from retail meat (n = 8), cows with mastitis (n = 7), and humans (HA-MRSA = 46 and CA-MRSA = 54) by molecular typing, virulence gene analyses, and antimicrobial susceptibility testing. MRSA isolates from retail meat were classified into sequence type (ST) 8/spa type t1767 (n = 4), ST8/t4133 (n = 1), ST59/t3385 (n = 1), ST88/t375 (n = 1), and ST509/t375 (n = 1). All seven MRSA isolates from cows with mastitis were ST8/t1767. 46 HA-MRSA were clonal complex (CC) 5, divided into t002 (n = 30), t045 (n = 12), and t7455 (n = 4). 54 CA-MRSA were classified into 6 different CCs: CC1 (n = 14), CC5 (n = 7), CC8 (n = 29), CC45 (n = 1), CC89 (n = 1), CC509 (n = 1), and into 16 different spa types including newly identified t17177, t17193, and t17194. The majority were CC8/t1767 (n = 16). CC of one CA-MRSA isolate (spa type t1767) was not classified. Among 41 CC8 MRSA (five from meat, seven from cows with mastitis, and 29 CA-MRSA), 14 ST8/SCCmec IVl isolates (three from meat, one from a cow with mastitis, and 10 CA-MRSA) had identical pulsed-field gel electrophoresis patterns and similar spa type (t1767, t4133, and t17177), and were typed as CA-MRSA/J (ST8/SCCmec IVl, positive for sec + sel + tst but negative for Panton-Valentine leukocidin and the arginine catabolic mobile element). These results suggest that there is a transmission cycle of CA-MRSA/J among meat, cows, and humans in Japan, although it is unclear whether the origin is cow.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) transmission between meat, cows, and humans in Japan was investigated. Findings suggest a cycle of community-acquired MRSA (CA-MRSA/J) involving these sources, highlighting potential foodborne transmission routes.
Area of Science:
- Microbiology
- Epidemiology
- Food Safety
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both healthcare and community settings.
- Understanding transmission routes is crucial for controlling MRSA spread.
Purpose of the Study:
- To investigate the role of retail meat in the transmission of MRSA between animals and humans in Japan.
- To characterize MRSA isolates from retail meat, cows with mastitis, and human infections.
Main Methods:
- Molecular typing (sequence typing, spa typing, pulsed-field gel electrophoresis) of MRSA isolates.
- Analysis of virulence genes and antimicrobial susceptibility testing.
- Comparison of MRSA strains from retail meat, cows, and human infections (healthcare-associated and community-acquired).
Main Results:
- MRSA isolates from retail meat, cows with mastitis, and community-acquired MRSA (CA-MRSA) in humans shared common molecular types, particularly ST8/t1767.
- A specific subtype, CA-MRSA/J (ST8/SCCmec IVl), was identified in meat, cows, and human isolates, exhibiting identical genetic profiles.
- Healthcare-associated MRSA (HA-MRSA) isolates belonged to different clonal complexes, primarily CC5.
Conclusions:
- Evidence suggests a transmission cycle of CA-MRSA/J among retail meat, cows, and humans in Japan.
- Retail meat may act as a vehicle for MRSA transmission.
- Further research is needed to pinpoint the origin of this transmission cycle.
