Molecular epidemiology of meticillin-resistant Staphylococcus aureus in fourteen cities in China from 2005 to 2006
Abstract number: P1434
Wang H., Liu Y., Du N., Shen E., Niu J., Sun H., Xu Y., Chen M.
Objective: To investigate the prevalence, antimicrobial resistance pattern, and the molecular epidemiology of MRSA in multiple centres of China from 2005 to 2006, and to evaluate the antimicrobial activities of tigecycline, daptomycin, and ceftobiprole against MRSA.
Methods: From 2005 to 2006, 1529 consecutive and non-repetitive Staphylococcus aureus were collected from 14 cities. The MICs of antibacterial agents were determined by agar dilution. The genotypes of SCCmec were determined by multiplex PCR. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to type MRSA. Panton-valentine leukocidin (pvl) gene was detected by PCR for all S. aureus.
Results: The mean prevalence of MRSA was 50.4% (408/809) in 2005, and 43.9% (315/717) in 2006, respectively. Shanghai has the highest MRSA prevalence (74.0%), followed by Qingdao (69.8%), Xi`an (68.0%), and Dalian (61.5%). The prevalence of MRSA was the lowest in Changchun (24.2%), Nanjing (25.4%), Shenzhen (22.4%) and Urumchi (29.2%). Only 4.2%-12.6% of MRSA were susceptible to erythromycin, quinolones, gentamicin, or tetracycline. About 78.6% of isolates were susceptible to trimethoprim/sulfamethoxazole. All isolates were susceptible to teicoplanin and vancomycin. Ceftobiprole, daptomycin, tigecycline, and linezolid had excellent activities with MIC50 and MIC90 of 2, 2 mg/L; 0.5, 0.5 mg/L; 0.125, 0.25 mg/L; 1, 2 mg/L, respectively. SCCmec type III and II accounted for 66.1% (478/723) and 14.1% (102/723), respectively. However, in Shenyang and Dalian, SCCmec II was more common than type III. PFGE typing found 24 different patterns. Clone A accounted for 50.1%, existing in 12 cities and clone R for 23.5%, and existing in 9 cities. Six sequence types (ST) were found in 53 representative isolates, with ST239 accounting for 75.5% and ST5 for 17.0%. The prevalence of pvl gene in all S. aureus was 9.4%. Two isolates from Guangzhou in 2006 belonged to community-acquired MRSA (CA-MRSA), one with ST88-SCCmec IV, the other one with ST59-SCCmec IV.
Conclusions: The prevalence of MRSA differed in areas in China. The most predominant types of MRSA in China were ST239-SCCmecIII and ST5-SCCmecII, which indicated that several international epidemic MRSA clones might exist in China. Clone spread resulted in the higher prevalence of MRSA in big teaching hospitals. CA-MRSA was uncommon in China. Ceftobiprole, daptomycin, tigecycline and linezolid showed excellent activities against all MRSA tested.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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