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Updated: Feb 19, 2026
Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
Published on: September 5, 2013
Methicillin-Resistant Staphylococcus aureus Sequence Type (ST) 5 Isolates from Health Care and Agricultural Sources
Samantha J Hau1, Steven Kellner2, Kirsten C Eberle2
1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.
Abstract:
Staphylococcus aureus is part of the nasal microbiome of many humans and has become a significant public health burden due to infections with antibiotic-resistant strains, including methicillin-resistant S. aureus (MRSA) strains. Several lineages of S. aureus, including MRSA, are found in livestock species and can be acquired by humans through contact with animals. These livestock-associated MRSA (LA-MRSA) isolates raise public health concerns because of the potential for livestock to act as reservoirs for MRSA outside the hospital setting. In the United States, swine harbor a mixed population of LA-MRSA isolates, with the sequence type 398 (ST398), ST9, and ST5 lineages being detected. LA-MRSA ST5 isolates are particularly concerning to the public health community because, unlike the isolates in the ST398 and ST9 lineages, isolates in the ST5 lineage are a significant cause of human disease in both the hospital and community settings globally. The ability of swine-associated LA-MRSA ST5 isolates to adhere to human keratinocytes in vitro was investigated, and the adherence genes harbored by these isolates were evaluated and compared to those in clinical MRSA ST5 isolates from humans with no swine contact. The two subsets of isolates adhered equivalently to human keratinocytes in vitro and contained an indistinguishable complement of adherence genes that possessed a high degree of sequence identity. Collectively, our data indicate that, unlike LA-MRSA ST398 isolates, LA-MRSA ST5 isolates do not exhibit a reduced genotypic or phenotypic capacity to adhere to human keratinocytes.IMPORTANCE Our data indicate that swine-associated livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) ST5 isolates are as capable of adhering to human skin and have the same genetic potential to adhere as clinical MRSA ST5 isolates from humans. This suggests that humans in contact with livestock have the potential to become colonized with LA-MRSA ST5 isolates; however, the genes that contribute to the persistence of S. aureus on human skin were absent in LA-MRSA ST5 isolates. The data presented here are important evidence in evaluating the potential risks that LA-MRSA ST5 isolates pose to humans who come into contact with livestock.
Insights
Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) ST5 isolates from swine can adhere to human skin as effectively as clinical MRSA ST5. However, these swine-associated LA-MRSA ST5 isolates lack genes for prolonged persistence on human skin.
Area of Science:
- Microbiology
- Public Health
- Infectious Diseases
Background:
- Staphylococcus aureus, including antibiotic-resistant methicillin-resistant S. aureus (MRSA), is a common nasal bacterium and a public health concern.
- Livestock-associated MRSA (LA-MRSA) strains, found in animals like swine, can transfer to humans, raising concerns about animal reservoirs.
- LA-MRSA ST5 isolates from swine are particularly concerning due to their global association with human diseases, unlike ST398 and ST9 lineages.
Purpose of the Study:
- To investigate the adherence capacity of swine-associated LA-MRSA ST5 isolates to human keratinocytes.
- To compare the adherence genes of swine-associated LA-MRSA ST5 with clinical MRSA ST5 isolates from humans without livestock contact.
- To evaluate the potential risk posed by swine-associated LA-MRSA ST5 to humans interacting with livestock.
Main Methods:
- In vitro adherence assays using human keratinocytes were performed with swine-associated LA-MRSA ST5 isolates.
- Adherence genes harbored by these isolates were identified and analyzed.
- Comparison of adherence capabilities and gene profiles between swine-associated LA-MRSA ST5 and human clinical MRSA ST5 isolates.
Main Results:
- Swine-associated LA-MRSA ST5 isolates demonstrated equivalent adherence to human keratinocytes compared to clinical MRSA ST5 isolates.
- Both isolate groups possessed an indistinguishable set of adherence genes with high sequence identity.
- LA-MRSA ST5 isolates lacked genes crucial for the persistence of S. aureus on human skin.
Conclusions:
- Swine-associated LA-MRSA ST5 isolates possess the same adherence potential to human skin as clinical MRSA ST5 isolates.
- Humans in contact with livestock may become colonized by swine-associated LA-MRSA ST5.
- While capable of initial adherence, LA-MRSA ST5 isolates may not persist on human skin due to the absence of specific genes.
