Single nucleotide polymorphism analysis indicates genetic distinction and reduced diversity of agricultural methicillin resistant Staphylococcus aureus (MRSA) ST5 isolates compared to clinical MRSA ST5 isolates

Authors: HAU, SAMANTHA - Iowa State University; ALLUÉ-GUARDIA, ANNA - University Of Texas At San Antonio; RUSCONI, BRIGIDA - University Of Texas At San Antonio; HAAN, JISUN - University Of Minnesota; DAVIES, PETER - University Of Minnesota; FRANA, TIMOTHY - Iowa State University; EPPINGER, MARK - University Of Texas At San Antonio; Nicholson, Tracy

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2018
Publication Date: 9/11/2018
Citation: Hau, S.J., Allué-Guardia, A., Rusconi, B., Haan, J.S., Davies, P.R., Frana, T.S., Eppinger, M., Nicholson, T.L. 2018. Single nucleotide polymorphism analysis indicates genetic distinction and reduced diversity of swine-associated methicillin resistant Staphylococcus aureus (MRSA) ST5 isolates compared to clinical MRSA ST5 isolates. Frontiers in Microbiology. 9:2078. https://doi.org/10.3389/fmicb.2018.02078.
DOI: https://doi.org/10.3389/fmicb.2018.02078

Interpretive Summary: Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) are bacteria carried by or obtained from swine and other livestock. Public health concerns surround this connection because livestock may serve as the largest MRSA reservoir outside of the hospital setting. Although the predominant sequence types (ST) or lineages in Europe (ST398) and in Asia (ST9) are considered livestock adapted, North American swine also harbor ST5, a globally disseminated and highly pathogenic lineage of MRSA. This study applied whole genome sequencing and single nucleotide polymorphism (SNP) typing to compare the population structure and genetic relatedness between swine associated and human clinical MRSA ST5 isolates. The established high-resolution phylogenomic framework revealed that the MRSA ST5 isolates obtained from swine or swine environments (LA-MRSA) are genetically distinct and separate from clinical MRSA ST5 obtained from human clinical settings. LA-MRSA isolates were found to be clonal within farms. In contrast, greater genome plasticity, or evidence of DNA exchange allowing quick adaption to survive diverse environmental conditions, was observed among clinical MRSA ST5 isolated obtained from human clinical settings. Collectively, our data indicate that LA-MRSA and clinical MRSA ST5 isolates are genetically distinct and transmission between the agricultural and clinical setting is not occurring.

Technical Abstract: Livestock associated MRSA (LA-MRSA) are carried by or obtained from swine and other livestock. Public health concerns surround this connection because livestock may serve as the largest MRSA reservoir outside of the hospital setting. Although the predominant European (ST398) and Asian (ST9) lineages of LA-MRSA are considered livestock adapted, North American swine also harbor ST5, a globally disseminated and highly pathogenic lineage. This study applied whole genome sequencing and single nucleotide polymorphism (SNP) typing to compare the population structure and genetic relatedness between swine associated and clinical MRSA ST5 isolates. The established high-resolution phylogenomic framework revealed that LA-MRSA and clinical MRSA ST5 are genetically distinct. LA-MRSA isolates were found to be clonal within farms, while greater genome plasticity was observed among sampled clinical MRSA ST5. Collectively, our data indicate that LA-MRSA and clinical MRSA ST5 isolates are genetically distinct and transmission between the agricultural and clinical setting is not occurring.