Study On Detection And Resistance Of Staphylococcus Aureus Enterotoxin Gene

ObjectiveTo detect the methicillin resistant staphylococcus aureus(MRSA) by using mecA genes polymerase chain reaction(PCR) method and to learn the distribution and resistance of MRSA in the Second Xiang Ya Hospitals of Central South University.To detect the staphytococal exterotoxin(SE) genes from clinical specimens and analyze the carrier condition and resistance of exterotoxin genes.Methods1.According to the quences of MRSA mecA genes,primers were selected and were used the amplity mecA gene.Meanwhile,we identificated the MRSA in 124 staphylococcus aureus that isolated from the Second Xiang Ya Hospitals of Central South University August 2006 to May 2008 and analyze the resistance.2.Primers of staphylococcal exterotoxin genes were designed.A total of 124 sample were isolation and identified of stappylococcus aureus were comlified respectively by PCR with above mentioned primers inorder to investigate the distribution of staphylococcal exterotoxin.And analyze the resistance of major enterotoxin gene.Reults1.With 67 strain of staphylococcus aureus,the results of the mecA genes were observed。MRSA were multi-resistant..Except Penicillin and vancomycin and teicoplain resistance rate of MRSA to other antimicrobial agents is higher than that of MSSA(P＜0.05).All strains were sensitive to vancomycin and teicoplain.2.We detected the SEA-SEF gene and made the gene sequencing successfully.The genes of SEA,SEB,SEC(1-3),SED,SEF were checked out from 124 staphylococcus aureus isolates which were separated from clinical specimens and the genes of SEE was negative in all staphylococcus aureus.The detection rate of SEA,SEB,SEC,SEDand SEF was 90.5%,6.9%,61.3%,5.2%,25.9%and 93.5%of isolates have enterotoxin genes.The detection rate of enterotoxin genes was 100%in MRSA and rate of enterotoxin genes was 83.5%in MSSA.There is no significant difference between the MRSA and MSSA(p＞0.05).The isolates with more than one enterotoxin genes accounted for 76(66.4%) In these strains,carrying two kinds of enterotoxin SEA and SEC genes, SEA and SEF gene,carrying three kinds of enterotoxin SEA,SEC and SEF genes for the strains Lord,detection rates were 33.6%,7.8%,13.8%.3.SEF gene were detected in the MRSA and MSSA,the detection rate accounted for 34.3%,14.3%,that there is significant difference(p＜0.05).4.We analyze the resistance rate of three strain with SEA,SEC,SEF genes,respectively,there is not statistically different(p＞0.05).5.One kinds of portable SEA enterotoxin gene,carried two kinds of enterotoxin SEA+ SEC genes,SEA+SEF gene,carrying three kinds of enterotoxin SEA+SEC+SEF genes strains analysis of drug-resistant.In addition to teicoplanin,vancomycin-sensitive,the others have varying degrees of antibiotic resistance,drug resistance rate of 20%-100%,which carry SEA+SEF genes,as well as carrying SEA+SEC+SEF three kinds of genotypes in the resistant strain rates higher than the only one kinds of carrying SEA gene strains.6.Resistance rates of strains carring SEA + SEC + SEF genes were 75.0%was higher than resistance rates of strains carrying a separate SEA (28.6%),SEA + SEC(38.7%),there were significant difference(P＜0.05).Strains earring SEA + SEC + SEF,SEA + SEF,SEA genes resistant to amikacin were 75.0%,77.0%and 21.5%,Analysis the former two strains and strains carrying only SEA genes,there were significant difference(P＜0.05)Conclusion1.Results suggested that the PCR could be used in mecA and SE gene.The PCR assay also showed high specificity,sensitivity and easy operation.2.The resistant rates of MRSA in Second Xiang Ya Hospital of Central South University were higher and the isolates of MRSA were multi-resistant.3.There is no significant difference detection in rate of enterotoxin genes between the MRSA and MSSA.4.The three most common type of enterotoxin(SEA,SEC,SEF) genes in Second Xiang Ya Hospital of Centeral South University.There is distinctly different of detection rate of SEF genes in MRSA and MSSA.5.There were no significant relation between carring SEA,SEC,SEF 3 different types of enterotoxin gene and its drug-resistant strains.6.The strains carrying a variety of enterotoxin gene in the resistance rate is higher than the strains carrying only enterotoxin gene.