婴幼儿食品中金黄色葡萄球菌污染情况及其耐药基因和新型肠毒素基因的检测

本文调查了婴幼儿奶粉和米粉中金黄色葡萄球菌的污染状况,并且检测其耐药基因和新型肠毒素基因。采集陕西省2010年和2012年间不同品牌的婴幼儿奶粉和米粉692份,进行金黄色葡萄球菌污染检验,采用PCR对分离菌株进行31种耐药基因和9种新型肠毒素基因的检测。692份样品中金黄色葡萄球菌的检出率为7.80%,其中2010年所采样品的检出率为8.17%,2012年所采样品的检出率为7.38%。分离的75株菌最终检测出12种耐药基因和2种新型肠毒素基因,检出率最高的耐药基因是tet K(72.00%),其次是bla Z(36.00%),erm C(29.33%),tet(K)F(21.33%),lin A/lin A’(12.00%),dfr G(8.00%),tet L(6.67%)和acc(6')(5.33%),最少的为erm B,msr A、msr B和drf K(均为1.33%)。新型肠毒素基因仅检测出sen(44.00%)和ser(4.00%)。不同采样年份、生产季节和货架期的样品中金黄色葡萄球菌的污染率不存在显著差异。并且这些菌株主要携带四环素、青霉素和大环内酯类抗生素的耐药基因,以及新型毒素基因sen。

Prevalence of Staphylococcus aureus Contamination in Infant Foods and the Detection of Antibiotic Resistance Genes and New Enterotoxin Genes

The prevalence of S. aureus contamination in infant formula milk powder (PIF) and infant rice cereal (IRC) was investigated in this study, and the corresponding antibiotic resistance genes and novel enterotoxin genes were detected. A total of 692 PIF and IRC samples of different brands were collected in the Shaanxi province of China in 2010 and 2012 and screened for S. aureus. Polymerase chain reaction (PCR) was employed to detect 31 antibiotic resistance genes and nine novel enterotoxin genes among the isolates. The overall positive rate for S. aureus in 692 samples was 7.80%, including 8.17% among the samples collected in 2010 and 7.38% among the samples collected in 2012. Among the 75 isolated strains of S. aureus, 12 types of antibiotic resistance genes and two novel enterotoxin gene profiles were detected. The resistance gene with the highest detection rate was tetK (72.00%), followed by blaZ (36.00%), ermC (29.33%), tet(K)F (21.33%), linA/linA (12.00%), dfrG (8.00%), tetL (6.67%), and acc(6'') (5.33%), and the genes with the lowest detection rate were ermB, msrA, msrB, and drfK (all at 1.33%). Among the novel enterotoxin genes, only sen (44.00%) and ser (4.00%) were detected. No significant difference was found in the contamination rate of S. aureus among the samples from different sampling years and production months and with different shelf lives. Additionally, the primary antibiotic resistance genes that these strains carried conferred resistance to penicillin, tetracycline, and macrolide, and the main virulence gene was sen.