Antibiotic Resistance And Molecular Epidemiology Of Methicillin-resistant Staphylococcus Aureus

Objective: To investigate antibiotic resistance and distribution of PantonValentine leucocidin (PVL) of Staphylococcus aureus isolates recovered from eighteen teaching hospitals; Methicillinresistant Staphylococcus aureus (MRSA) were identified and characterized using SCCmec typing. Methods: Antibiotic resistance was studied by agar dilution method. Pulsedfield gel electrophoresis (PFGE) was used to type the chromosome DNA of MRSA strains. SCCmec typing (IV) of all clinical isolates of MRSA was performed by novel multiplex PCR assay. Results: The resistant rate of erythromycin, Clindamycin and Tetracycline were higher in MRSA. All of MRSA strains were susceptible to glycopeptides such as vancomycin and teicoplanin. The majority (94.1%) of the strains were resistant to erythromycin, Ciprofloxacin, Levofloxacin, Gatifloxacin, Clindamycin. The average rate of PVL+ isolates was 7.2% in SA isolates. The PVL-producing isolate rate of MRSA was less than that of MSSA, but there was no significant difference (P>0.05); the rate of outpatients isolates was higher than that of inpatients isolates, there was significant difference (P<0.05). SCCmec typing showed that most isolates from the first hospital of Shenyang were type II, the most isolates of Guangzhou and Shenzhen were untype, whereas SCCmec type III was the most frequent type in strains from other hospitals (63.4%). Twentyfour different PFGE patterns were found among 407 MRSA strains, most of MRSA were A colone (203, 50%). The first hospital of Shenyang was Q colone, Shanghai and Zhejiang were R colone. Conclusions: There existed remarkable difference of PVL carring rate, MRSA isolate rate, SCCmec typing, and epidemic colones. Through evaluating resourses of patients, we have not found CAMRSA.