婴幼儿奶粉和米粉中金黄色葡萄球菌的分离鉴定及其毒素基因检测

Isolation,Identification and Toxin Genes Detection of Staphylococcus aureus Strains from Infant Milk Powder and Infant Rice Cereal

目的:了解婴幼儿奶粉和米粉中金黄色葡萄球菌的污染及其毒素基因的携带情况。方法:采集陕西省18个地区不同品牌的婴幼儿奶粉143份和米粉224份,按国标法和PCR方法进行金黄色葡萄球菌分离鉴定;采用PCR方法检测ses基因、ets基因、tsst-1基因和pvl基因。结果:367份样品中检测出30个金黄色葡萄球菌污染样品,检出率为8.17%,其中奶粉11.19%(16/143)、米粉6.25%(14/224),分别从中分离鉴定出29株和25株金黄色葡萄球菌;从54株金黄色葡萄球菌中共检测到有64.8%(35/54)的菌株携带有毒素基因,其中奶粉72.4%(21/29)、米粉56.0%(14/25);奶粉分离株中检测到的毒素基因型有pvl、sea、seb、sed、seg、sea+pvl、seb+seg、seb+sed+seg、sec+pvl、sec+seg+pvl和seg+pvl,其检出率分别为10.3%(3/29)、3.4%(1/29)、3.4%(1/29)、3.4%(1/29)、6.9%(2/29)、6.9%(2/29)、6.9%(2/29)、3.4%(1/29)、3.4%(1/29)、13.8%(4/29)和10.3%(3/29);米粉分离株中检测到的毒素基因型有pvl、sed、seg、sea+seg+pvl、sec+pvl、sec+seg、sec+see+seg、sec+see+seg+pvl、see+pvl和seg+pvl,其检出率分别为8%(2/25)、4%(1/25)、4%(1/25)、4%(1/25)、4%(1/25)、8%(2/25)、4%(1/25)、4%(1/25)、4%(1/25)和12%(3/25)。奶粉和米粉中都没有检测到ets、tsst-1和seh、sei、sej基因。结论:婴幼儿奶粉和米粉中均存在一定程度的金黄色葡萄球菌的污染,且多数菌株都携带一定的毒素基因,这对消费这些产品的婴幼儿身体健康构成潜在的危险。

Objective： To investigate the prevalence and toxin genes profile of Staphylococcus aureus in infant milk powder and infant rice cereal marketed in Shaanxi province,China.Methods： Totally 367 various samples from 18 regions in Shaanxi province were tested by the national standard method to isolate Staphylococcus aureus;the nuc genes were examined to confirm Staphylococcus aureus status;Staphylococcus aureus enterotoxin genes,exfoliative toxins genes,toxic-shock syndrome toxin-1 gene and Panton-Valentine Leukocidin gene were detected by PCR.Results： Of 367 samples examined,30 were positive for Staphylococcus aureus,result in a positive rate of 8.17%（30/367）,including 11.19%（16/143） milk powder samples and 6.25%（14/224） rice cereal samples.From these positive samples,29 and 25 strains were isolated from milk powder and rice cereal samples respectively.Among all identified Staphylococcus aureus isolates,34 strains harbored at least one of the tested toxin genes.The toxins gene profiles detected in S.aureus from infant milk powder samples were pvl,sea,seb,sec,sed,seg,seb＋seg,sec＋seg and seb＋sed＋seg,and their positive rates were 44.82%（13/29）,10.34%（3/29）,13.79%（4/29）,17.24%（5/29）,6.89%（2/29）,41.38%（12/29）,10.34%（3/29）,10.34%（3/29） and 3.45%（1/29） respectively;The toxin gene profiles in S.aureus from infant rice cereal samples were pvl,sea,sec,sed,see,seg,sea＋seg,sec＋seg and sec＋see＋seg,and the positive rates were 36%（9/25）,4%（1/25）,20%（5/25）,4%（1/25）,12%（3/25）,36%（9/25）,4%（1/25）,16%（4/25） and 8%（2/25）,respectively.Neither ets,tsst-1,seh,sei nor sej genes were detected in infant milk powder or infant rice cereal.Conclusion： Infant milk powder and infant rice cereal in Shaanxi province were contaminated with S.aureus,some of which contained various toxin genes.The existence of the pathogen in these food products may constitute a potential risk for infants,health.