Analysis Of The Resistance Of Staphylococcus Aureus And Genotypes Of Methicillin Resistant Staphylococcus Aureus Strains Isolated From Several Hospitals In Anhui

Objective:To evaluate the three methods for detection of methicillin resistant staphylococcus aureus (MRSA) and analysis the resistance of staphylococcus aureus isolated from 34 hospitals in Anhui from January to December in 2005 To investigate the genotype of methicillin resistant Staphylococcus aureus(MRSA) and its resistanceMaterials and Methods:Isolates: Totally 187 strains of Staphylococcus aureus were collected from thirty four hospitals in Anhui between Januray and December in 2005.Method: MRSA were detected by cefoxitin disk, oxacillin disk diffusion as well as PCR amplification for the mecA gene, respectively.187 strains of S.aureus isolats were tested for minimus inhibitory concentration (MIC) to 17 kinds of antimicrobial agent with agar dilution method;A total of 85 MRSA clinical isolates were collected in Anhui province,MICof seventeen different antibacterial agents against the isolates were determined by agar dilution method.PCR amplified the mec associated hypervariable region(HVR)of MRSA,and the genotypes were classified based on the fragments of amplified products.The correlation of genotypes and antimicrobial resistance was analyzed . Result The rates of MRSA detected by cefoxitin disk, oxacillin disk diffusion as well as PCR amplification for the mecA gene were 51.34%, 55.08%, 45.45%, respectively, and the result of three groups had significant difference (P≤0.05). Cefoxitin disk diffusion method of the specificity and sensitivity were higher than oxacillin disk diffusion method. Except penicillin-G and ampicillin and chloramphenicol, a1l strains were sensitive to vancomycin, resistance rate of MRSA to other antimicrobial agents is higher than that of MSSA (p<0.01).85 strains of MRSA from Anhui province were grouped into A, B, C genotypes and unable type based on HVR polymorphism. A, B, C genotypes and unable type was respectively 17.8%, 23.3%, 58.8% and 14.12%. The resistance of the three genotypes had no significant diffence.ConclusionCefoxitin disk diffusion method can be used reliably in detecting and conforming MRSA. Resistance in MRSA was getting more and more serious, so detection and surveillance of them should be emphasized.MRSA were multi-drug resistant and can be divided into 3 genotypes and unable type based on the HVR PCR amplified products.HVR PCR method is a rapid and convenient method for molecular epidemiology study of MRSA infections.