| Objective Food borne diseases caused by Staphylococcus aureus(S.aureus)are in creasingly threatening human health and food safety.In this study,samples of re ady-to-eat meat in Hefei were collected and the pollution of S.aureus was detect ed,and drug resistance analysis and multi site sequence typing were carried out,in order to preliminarily reveal the contamination of Staphylococcus aureus in r eady-to-eat meat in this area.Methods From October 2017 to October 2018,550 samples of ready-to-eat meat were collected from supermarkets and open veget able markets in Hefei.According to the method of GB4789.10-2010,the samples were analyzed qualitatively and quantitatively,and the selective isolation of Staph ylococcus aureus was carried out by using theglycetes color plate.The drug resis tance of the isolates was analyzed by K-B disk diffusion method,ST typing was carried out by multi site sequence typing method,and then phylogenetic tree w as constructed by eBURST.Results Qualitative and quantitative detection of Stap hylococcus aureus showed that 31 positive samples were detected from 550 samp les,with a contamination rate of 5.6%(31/550).Among them,16 samples were detected from supermarkets with a contamination rate of 5.7%.Fifteen samples were detected from vegetable markets with a contamination rate of 5.5%.There was no statistical difference between the two groups(P=0.357).The detection rat e was 8.7%(15/185)for halogen products,6.3%(11/174)for roast meat product s,2.7%(4/147)for fried products,0.7%(1/141)for dried meat products,and no Staphylococcus aureus was detected in canned products.Quantitative detection o f MPN showed that 67.7%(21/31)of the positive samples had MPN values ran ging from 0.3 to 1.0 MPN/g,22.6%(7/31)of the positive samples had MPN values ranging from 1.0 to 10 MPN/g,6.5% of the positive samples had MPN val ues ranging from 10 to 110 MPN/g,and 1 case had MPN values greater than 110 MPN/g.Thirty-one strains of Staphylococcus aureus were sensitive to cefoxiti n,chloramphenicol,linezolid and vancomycin.No MRSA strains were detected,but the resistance rates to penicillin G,streptomycin,erythromycin and kanamycin were 80.6%,48.4%,45.2% and 41.9%,respectively.Among them,61.3%(19/31)were resistant to more than three types of antibiotics,and 12.9%(4/31)were re sistant to more than six types of antibiotics.The genotypes of 31 Staphylococcus aureus isolates were analyzed by MLST,and 11 genotypes were obtained,inclu ding ST6,ST7,ST15,ST59,ST72,ST188,ST398 and ST196,with ST188(19.4%),ST72(16.1%),ST7(16.1%)and ST398(12.9%).There were six clonal co mplexes in all strains,CC5,CC14,CC59,CC398 and CC2483,among which C C5(51.6%)was the dominant type.Conclusion Staphylococcus aureus contamina tion exists in stewed meat and roast meat in Hefei,and the proportion of multidrug resistant strains is high,which has potential threat to the health of consume rs.It is necessary to continuously monitor the contamination rate,bacterial resist ance and genotype epidemic trend,and improve the risk assessment of foodborne Staphylococcus aureus infection in the region. |
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