Abstract:

Objective To investigate the antibiotic resistance of Staphylococcus aureus in communities and hospitals in Beijing.Methods To detect the susceptibility of 11 kinds of antibiotics of 471 strains SA isolated in Beijing with agar dilution method(422 isolates from outpatients in 1993—2000,49 from burnt inpatients),comparing the susceptibility difference of those strains.To the resistance gene of MRSA was detected with polymerase chain reaction(PCR).Results In community-acquired infection isolates,MRSA increased significantly from 12.2% to 29.8% during 1993 to 2000.In nosocomial infection isolates,MRSA was 63.3% in 2000,a little bit lower than that of mid-1990's.All the Staphylococcus aureus strains showed 100% resistance to penicillin.The resistance of SA to some non-β-lactams were: erythromycin 80%,tetracycline 70%,clindamycin 60%,chloramphenical 50%.In community-acquired infection isolates,resistance to ciprofloxin increased significantly from(2.4)% to(21.3)% from 1993 to 2000,no isolates was found to be resistant to gentamycin,rifampin,vancomycin and fusidic acid.In nosocomial infection isolates,the resistance percentage to gentamycin,ciprofloxin and rifampin were 63.3%,63.3% and 57.1% respectively.No strain was found to be resistant to vancomycin and fusidic acid.All the MRSA strains were multi-drug resistant.MRSA strains showed higher resistance percentage to erythromycin,tetracycline,clindamycin,chloramphenical and ciprofloxin than MSSA.Detection of mecA gene by PCR showed that all the high-level methicillin-resistant strains were mecA gene positive,all the low-level methicillinresistant strains were mecA gene negative.Conclusion The results indicate that the resistance rate of SA in Beijing is going up.Detection of mecA gene by PCR is an easy and quick way of screening MRSA strains.

Key words: methicillin-resistant Staphylococcus aureus, resistance susceptibility, polymerase chain reaction