Joint Research Center for Food Safety

Shanghai, China

Joint Research Center for Food Safety

Shanghai, China

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Xu J.,Joint Research Center for Food Safety | Xu J.,Shanghai JiaoTong University | Shi C.,Joint Research Center for Food Safety | Shi C.,Shanghai JiaoTong University | And 8 more authors.
Journal of Food Science | Year: 2014

Staphylococcus aureus is a recognized pathogen in humans, which causes nosocomial infections and food poisoning. The transmission of antibiotic resistant S. aureus (ARSA), especially methicillin-resistant S. aureus, between food products and humans has become a serious problem. Hence, it is necessary to monitor S. aureus through the food supply chain. In this study, the disk diffusion method and epsilometer test were performed to determine the prevalence of ARSA in 78 foodborne isolates using 18 antibiotics. The highest resistance frequency was found for penicillin G (74.4%), followed by erythromycin (59.0%) and clindamycin (44.9%), whereas no vancomycin-resistant isolates were found. The 78 isolates could be subtyped into 31 resistance profiles and 11 clusters based on their antimicrobial susceptibility. Furthermore, Polymerase chain reaction (PCR) screening for the presence of 13 genes conferring antibiotic resistance was conducted. The presence of resistance genes was relatively high: blaTEM (80.8%), ermB (41.0%), grlA (38.5%), ermC (35.9%), and aac6'/aph2" (35.9%). The incidence of antibiotic resistance was significantly correlated to food types (p = 0.018), with isolates from meat and raw milk more resistant to antibiotics than those from frozen food and vegetables.Practical Application: The antibiotic resistance of S. aureus has become a serious concern in foodstuffs and varies in different foods. Raw milk and meat have more resistant isolates than those from frozen food and vegetables. Resistance profiles and Ward's minimum variance method can be used to subtype isolates in different clusters. © 2014 Institute of Food Technologists®.


Song M.,Joint Research Center for Food Safety | Li Q.,Shanghai Institute For Food And Drug Controlshanghai201203 P R China | Zhang Y.,Joint Research Center for Food Safety | Song J.,The Affiliated Hospital Of Qingdao Universityqingdao266003 ina | And 2 more authors.
Journal of Food Safety | Year: 2016

Biofilm formation usually increases antimicrobial resistance capacity of Staphylococcus aureus, which poses considerable challenges to successful eradication of staphylococcal infections. Very little is known about the biofilm-forming capacity and antibiotic resistance pattern of dominant S. aureus clonal lineages in China. In this study, the disk diffusion method and the microtiter plate assay were, respectively, performed to determine the antibiotic resistance and biofilm-forming capacity of 84 different S. aureus isolates belonging to 10 dominant clonal lineages in China. It was shown that isolates of different clonal lineages had obvious variations in biofilm-forming capacity. Resistance to individual antibacterial agents was most frequently observed to erythromycin (72.6%) and azithromycin (72.6%). Then, all tested isolates were further screened for the presence of 16 resistance genes by polymerase chain reaction (PCR), and no significant correlation was found between clonal lineage and the distribution of resistance genes. Overall, our results indicate that biofilm producers of S. aureus have a greater likelihood to carry more antibiotic resistance genes than non-biofilm producers (p<.01), further implying that biofilm may promote the dissemination of antibiotic resistance determinants. Practical applications: Staphylococcus aureus is the leading cause of nosocomial infections and often associated with food poisoning worldwide. Biofilm formation of S. aureus influences the efficacy of antimicrobial therapy and promotes the persistence of infections; however, the knowledge about biofilm formation capacity of isolates belonging to different clonal lineages is little. Therefore, this study on biofilm formation capacity and antibiotic resistance pattern of dominant S. aureus clonal lineages could help to fix this information gap. © 2016 Wiley Periodicals, Inc.

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