Full-Text Search:
Home|Journal Papers|About CNKI|User Service|FAQ|Contact Us|中文
《Chinese Journal of Internal Medicine》 2001-03
Add to Favorite Get Latest Update

A study on the resistance of Staphylococcus aureus and the mechanisms of its resistance to fluoroquinolone

LEI Yanchang, GUI Xien, FENG Guoqin.The Second Affiliated Hospital, Hubei Medical University, Wuhan 430071, China  
Objective To investigate the resistance of Staphylococcus aureus (SA) and the mechanisms of its resistance to fluoroquinolones(FQ).Methods The susceptibility of SA (200 strains) to 12 antibiotics was detected by disc diffusion, The minimal inhibitory concentrations (MICs) of 52 strains to three FQ were determined by agar dilution method.52 strains resistant to ciprofloxacin (MIC≥4 mg/L)were studied for the presence of point mutations in the gyrA gene and grlA gene by polymerase chain reaction restriction fragment length polymorphisms(PCR RFLP) method and for the expresion of norA gene by reserpine reverse test respectively.Results 34% of the strains were resistant to oxacillin(methicillin resistant Staphylococcus aureus, MRSA) and other antimicrobials as well, but no vancomycin resistant strain was found.The resistance rate of MRSA to ciprofloxacin was 79.4% and cross resistance existed.It was found that 42 strains (80.8%) had a mutation at gyrA codon 84(TCA→TTA or GCA).Mutations at grlA codon 80(TCC→TAC or TTC) and codon 84 (GAA→AAA)were observed in 10(19 2%) and 14 strains(26 9%) respectively.Strains containing mutations in gyrA or both gyrA and grlA gene showed a higher level of ciprofloxacin resistance than those with alternation in grlA gene but with wild type gyrA or non gyrA mutants ( P 0.01).Decreased MICs to ciprofloxacin, norfloxacin and levofloxacin in reserpine reverse test indicated the presence of norA phenotype.Conclusions It is clear that emergence of resistant SA strains will continue to be a problem, especialy in MRSA which was resistant to most of the antibiotics. Fluoroquinolones are not the choice for MRSA now. The resistance to fluoroquinolones in clinical isolates of SA are due to the mutations of the gyrA and grlA gene encoding the target enzyme of fluoroquinolones and cell membrane resistance.Mutations of grlA gene may differ in different districts.
【CateGory Index】: R446.5
Download(CAJ format) Download(PDF format)
CAJViewer7.0 supports all the CNKI file formats; AdobeReader only supports the PDF format.
©2006 Tsinghua Tongfang Knowledge Network Technology Co., Ltd.(Beijing)(TTKN) All rights reserved