奶牛乳房炎源性产色葡萄球菌的肠毒素基因检测

Detection of enterotoxin genes in Staphylococcus chromogenes isolated from bovine mastitis

前期流行病学调查结果显示,凝固酶阴性葡萄球菌(CNS)是引起我国奶牛乳房炎的主要致病菌之一,而产色葡萄球菌分离率最高的一种CNS。为探明奶牛乳房炎源性产色葡萄球菌肠毒素基因的分布特征,本试验采用PCR方法,对来源于我国11个省份20个奶牛场临床乳房炎奶样中分离鉴定的36株产色葡萄球菌进行9种肠毒素基因的检测,同时对生物被膜的产生能力及生物被膜相关调控基因(ica A、ica D和bap)进行检测。结果显示,在36株产色葡萄球菌中,33株携带至少一种肠毒素基因,占比92%;18株携带两种及以上肠毒素基因,占比50%。检出率较高的肠毒素基因依次为seh(50%)、sei(47%)、sea(36%)和sec(25%)。生物被膜检测结果显示,29株产色葡萄球菌具有生物被膜产生能力,占比81%;此外,36株产色葡萄球菌中,19株携带生物被膜相关调控基因(53%),以ica D基因为主。在奶牛乳房炎源性产色葡萄球菌中,肠毒素基因的高检出率显示其具有较强的乳房炎致病潜力,同时可对奶制品安全生产造成隐患。产色葡萄球菌较强的生物被膜产生能力能够使其对抗生素的耐药性增强,从而降低乳房炎的治疗效果。

The preliminary epidemiological survey showed that coagulase-negative staphylococci（ CNS） is one of the leading pathogens causing bovine mastitis in China,and the proportion of Staphylococcus chromogenes（ S. chromogenes） is the highest. To find out the distribution characteristics of enterotoxin genes in S. chromogenes from bovine mastitis,PCR method was used to detect 9 enterotoxin genes（ sea,seb,sec,sed,see,seg,sei,sej and seh） in 36 strains of S. chromogenes isolated from 20 dairy farms in 11 provinces of China. Meanwhile,the biofilm formation capacity and biofilm-related genes（ ica A,ica D and bap） were detected. The results showed that in these 36 strains of S. chromogenes,33 strains carried at least one type of enterotoxin gene,the carrying rate was 92%,and 18 strains carried two or more types,accounting for 50%. The dominant enterotoxin genes were seh and sei,accounting for 50% and47%,followed by sea and sec,which represented 36% and 25%. The enterotoxin genes with high detection rate were seh（ 50%）,sei（ 47%）,sea（ 36%） and sec（ 25%）. The results of biofilm detection showed that 29 strains of S. chromogenes were biofilm producer,which accounted for 81%. In addition,19 of 36 strains of S. chromogenes carried biofilm gene（ 53%） and ica D gene was the most prevalent. The high detection rate of enterotoxin genes in S. chromogenes derived from cow mastitis showed that S. chromogenes had a strong potential for the pathogenesis of mastitis,and caused a hidden danger to the safe production of dairy products. S. chromogenes has strong biofilm formation ability,which can enhance its resistance to antibiotics,thereby reducing the therapeutic effect of mastitis.