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P2-136 Genotypic and Phenotypic Characterization of Enterotoxigenic Methicillin-resistant Staphylococcus aureus Isolates from Bovine Raw Milk in Korea

Monday, July 27, 2015
Exhibit Hall (Oregon Convention Center)
Jae Won Song , Seoul National University , Seoul , Korea, Republic of (South)
Young Kyung Park , Seoul National University , Seoul , Korea, Republic of (South)
Yeon Soo Chung , Seoul National University , Seoul , Korea, Republic of (South)
Dae Ho Kim , Seoul National University , Seoul , Korea, Republic of (South)
Sook Shin , Seoul National University , Seoul , Korea, Republic of (South)
Jae Hong Kim
Yong Ho Park , Seoul National University , Seoul , Korea, Republic of (South)
Introduction: Staphylococcus aureus is one of the major etiological pathogen of bovine mastitis. Also, methicillin-resistant S. aureus (MRSA) has been constantly isolated from bovine milk and is known as the causative agents of various clinical infectious diseases. The presence of MRSA in milk can be regarded as a potential hazard for public health. 

Purpose: We investigated the antimicrobial resistance, virulence and genotype of MRSA isolated from bovine raw milk in Gyeonggi province of Korea.

Methods: A total of 1,222 raw milk samples were collected from 47 dairy farms from Gyeonggi province of Korea, during 2011 to 2012. Of these samples, 643 milk samples that had more than 500,000 SCC/ml were further examined for the isolation of mastitis-causing Staphylococci. The spa typing, SCCmec typing and PFGE were also analyzed. Antimicrobial resistance was determined using a disk-diffusion test and MIC determination by broth dilution test were also performed according to the CLSI guidelines.  

Results: All MRSA isolates showed four or more drug resistant and four PFGE types (A-D). The most frequently detected staphylococcal enterotoxin (SE) gene profile was seg, sel, sek, sem, sen and seo genes (20 isolates, 87%). None of the MRSA carried the vanA, vanB, eta, etb, tsst, and PVL genes. Nine of the 23 MRSA origination from three farms belonged to SCCmec type IVa-t324. Just three isolates from the same dairy farm of the SCCmec type II-t002. 

Significance: Our results show that there are significant similarities in genotypic characteristics among MRSA isolates from different farms in Korea. And there is a possibility of clonal transmission of enterotoxigenic MRSA from one dairy farm to another dairy farm. Investigating distributions of MRSA in dairy herds is important for establishing infection control strategies by providing basic information.

Back to: Poster Session 2 – Laboratory and Detection Methods; Meat, Poultry and Eggs; Dairy and Beverages; Food Law and Regulation; General Microbiology; Modeling and Risk Assessment
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