Detection of 9 Enterotoxin Genes in Staphylococcus aureus From Milk of Cows with Mastitis

The aim of this study was to compare the difference of occurrence of 9enterotoxin genes in Statphylococcus aureus recovered from milk of cows with clinical or subclinical mastitis.70 and 55 S.aureus strains from cows with clinical and subclinical mastitis were isolated,respectively,and 9enterotoxin genes were tested by using PCR method.The results showed that an overall of 65.7%isolates from cows with cinical mastitis carried enterotoxin genes,and the detection rates of SEA,SEE and SEI were 12.9%(9isolates),4.3%(3isolates)and 60.0%(42isolates),respectively.Among these isolates,55.7%(38isolates)of them possessed one type of enterotoxin gene,while 11.4%(8isolates)of them possessed more than two gens.For isolates from cows with subclinical mastitis,89.1%of them carried enterotoxin genes,and the detection rates of SEA,SEB,SEC,SED,SEE,SEG,SEH,SEI and SEJ were 10.9%(6isolates),25.5%(14isolates),7.3%(4isolates),5.5%(3isolates),25.5%(14isolates),47.3%(26isolates),29.1%(16isolates),10.9%(6isolates)and 32.7%(18isolates),respectively.Among these isolates,29.1%(16isolates)of them possessed one type of enterotoxin gene,while 60.0%(33isolates)of them possessed more than two gens.Our results indicated that enterotoxin genes were wildly distributed in mastitis-related S.aureus strains.It is also suggested that in S.aureus strains related with clinical mastitis,SEI was the prominent enterotoxin,while in strains related with subclinical mastitis,more types and more complex of enterotoxin genes were presented.