The epidemiological study of methicillin-resistant Staphylococcus aureus in Shanghai

Abstract

Objective To investigate antibiotic resistance and molecular epidemiology profile of methicillin-resistant Staphylococcus aureus (MRSA) in Shanghai. Methods The antibiograms of 140 MRSA isolates from 5 hospitals for 13 drugs were analyzed by agar dilution and broth dilution. The PVL gene and SCCmec were detected by PCR; The clonal relatedness of 140 isolates were determined by PFGE and 39 strains were chosen to be characterized further by spa typing. Results All 140 MRSA are PVL negative and most of them were identified as SCCmec Ⅲ [45.7% (64/140)], followed by SCCmec Ⅲ a [25.0% (35/140)], SCCmecⅢb [14.3% (20/140)], SCCmecⅡ [10.7% (15/140)] and SCCmecⅣ [4.3% (6/140)]. All isolates were susceptible to vancomycin, teicoplanin and daptomycin. The resistance to gentamicin, sulphamethoxazole and clindamycin was 98. 6% (138/140), 98. 6% (137/140) and 97. 9% (137/140), respectively. Resistance to erythromycin, ciprofloxacin and tetracycline was above 80%, and resistance to rifampicin was 10. 7% (15/140). Sixteen different PFGE patterns(A-P) were found and most of MRSA belonged to group C[30. 7% (43/140)] ,B[13.6% (19/140)]and Ⅰ [10. 7% (15/140)]. Among 39 strains with prevalent PFGE patterns, 4 spa genotypes were identified: t002133. 33% (13/39)] ,t030 [12. 82% (5/39)] ,t037[51.28% (20/39)]and t459[2. 57% (1/39)]. Conclusions Sixteen different PFGE patterns and 4 spa genotypos were found from 5 hospitals in Shanghai. The most popular MRSA clone is PVL negative, SCCmec Ⅲ, with resistant profile of erythromycin, ciprofloxacin,clindamycin,etracycline, gentamicin,and sulphamethoxazole [E-C-L-T-G-M-]. This result suggests that hospital infection control and reasonable antibiotic usage are critical. Key words: Methicillin resistance; Staphylococcus aureus; Epidemiology, molecular; Electrophoresis, gel, pulsed-field