Genotypic Characterization of Methicillin-resistant Staphylococcus aureus Isolated from Pigs and Retail Foods in China

• Published in: Biomedical and environmental sciences 2017-08, Vol.30 (8), p.570-580
• Main Authors: WANG, Wei, LIU, Feng, ZULQARNAIN, Baloch, ZHANG, Cun Shan, MA, Ke, PENG, Zi Xin, YAN, Shao Fei, HU, Yu Jie, GAN, Xin, DONG, Yin Ping, BAI, Yao, LI, Feng Qin, YAN, Xiao Mei, MA, Ai Guo, XU, Jin
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; Antimicrobial susceptibility; China; Food Microbiology; Genetic diversity; Humans; Methicillin - pharmacology; Methicillin Resistance; Methicillin-resistant Staphylococcus aureus; Methicillin-Resistant Staphylococcus aureus - genetics; Methicillin-Resistant Staphylococcus aureus - isolation & purification; MRSA; Nose - microbiology; Pig; Retail food; Swine - microbiology; 中国猪; 基因型; 脉冲场凝胶电泳; 遗传多样性; 金黄色葡萄球菌; 零售; 食品分离
• ISSN: 0895-3988; 2214-0190
• DOI: 10.3967/bes2017.076

Objective To investigate the genotypic diversity of Methicillin-resistant Staphylococcus aureus （MRSA） isolated from pigs and retail foods from different geographical areas in China and further to study the routes and rates of transmission of this pathogen from animals to food. Methods Seventy-one MRSA isolates were obtained from pigs and retail foods and then characterized by multi-locus sequencing typing （MLST）, spa typing, multiple-locus variable number of tandem repeat analysis （MLVA）, pulsed-field gel electrophoresis （PFGE）, and antimicrobial susceptibility testing. Results All isolated MRSA exhibited multi-drug resistance （MDR）. Greater diversity was found in food-associated MRSA （7 STs, 8 spa types, and 10 MLVA patterns） compared to pig-associated MRSA （3 STs, 1 spa type, and 6 MLVA patterns）. PFGE patterns were more diverse for pig-associated MRSA than those of food-associated isolates （40 vs. 11 pulse types）. Among the pig-associated isolates, CC9-ST9-t899-MC2236 was the most prevalent clone （96.4%）, and CC9-ST9-t437-MC621 （20.0%） was the predominant clone among the food-associated isolates. The CC9-ST9 isolates showed significantly higher antimicrobial resistance than other clones. Interestingly, CC398-ST398-t034 clone was identified from both pig- and food-associated isolates. Of note, some community- and hospital-associated MRSA strains （t030, t172, t1244, and t4549） were also identified as food-associated isolates. Conclusion CC9-ST9-t899-MC2236-MDR was the most predominant clone in pigs, but significant genetic diversity was observed in food-associated MRSA. Our results demonstrate the great need for improved surveillance of MRSA in livestock and food and effective prevention strategies to limit MDR-MRSA infections in China.