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Isolation, Characterization and Molecular Epidemiology of Methicillin Resistant Staphylococcus aureus (MRSA) in sheep Milk in American and Brazilian herds

Research Scholar

Guilherme Santana de Moura, Veterinary Preventive Medicine (Brazil)
Bayleyegn Molla, Co-Researcher
Andréia Vielmo, Co-Researcher
Wondwossen A Gebreyes, Faculty Mentor


Guilherme Santana de Moura is a graduate student studying veterinary medicine at the Federal University of Paraíba, and is sponsored by the Science Without Borders program of the National Research Council. He has worked in preventive veterinary medicine and public health with emphasis on diagnosis of diseases with zoonotic potential. His mentor in his research at Ohio State is Wondwossen A Gebreyes.

What is the issue or problem addressed in your research?

Foodborne diseases, in particular those related to milk and milk products, have recently become a matter of great public concern. All domestic animals, also small ruminants, develop different diseases associated with Staphylococcus aureus; this bacterium is often isolated in cases of mastitis, cutaneous lesions, abscesses, etc. The most important reason to look into S. aureus in sheep milk is not only from the point of veterinary medicine but also the public health aspects.

What methodology did you use in your research?

This study aims to determine the occurrence and prevalence of Methicillin Resistant S. aureus (MRSA) in milk from sheep. Isolates recovered from sheep milk will be characterized phenotypically and genotypically to determine the antimicrobial resistance patterns, associated virulence genes and their genotypic relatedness Molecular assays such as PCR and the pulsed-field gel electrophoresis (PFGE) will be used in characterizing the isolates. Sheep milk samples will be collected from selected herds in Ohio using a cross-sectional sampling study design and processed at the Infectious diseases Molecular Epidemiology Laboratory (IDMEL). The analysis includes isolation and identification of S. aureus isolates and antimicrobial susceptibility testing. The isolates will be further characterized using molecular approaches such as  PCR to determine  nuc gene to confirm S. aureus. The confirmed S. aureus isolates will be further tested for methicillin resistance gene, mecA. We will test isolates for the presence of enterotoxin genes (seA-seI) to determine the food safety significance of MRSA in sheep milk. MRSA isolates found in U.S. sheep herds will be compared with isolates of Brazilian origin using PFGE genotyping.

What are the purpose/rationale and implications of your research?

This study will provide the occurrence, prevalence and characteristics of MRSA in Ohio sheep herds in comparison with those from Brazil. S. aureus is one of the major causes intramammary infections in livestock and is also a significant human pathogen and a of great public health concerns.