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目的研究手术感染大肠埃希菌gyrA基因突变及耐药性,以指导临床治疗中抗生素的合理选用。方法分离提取40株大肠埃希菌gyrA基因,进行PCR扩增及基因测序,分析突变位点,并进行细菌药敏试验。结果药敏试验显示,40株手术感染大肠埃希菌分离株(诺氟沙星耐药)对萘啶酸、诺氟沙星、培氟沙星的耐药率均为100.0%,对氧氟沙星、左氧氟沙星、环丙沙星、依诺沙星的耐药率分别为90.0%、75.0%、75.0%和70.0%,对加替沙星和莫西沙星耐药率为15.0%和10.0%。PCR扩增gyrA基因,大小为285bp。对其进行测序分析,此基因的突变多数发生在密码子编码氨基酸的第83位和第87位,主要有:83位丝氨酸(Ser)突变为亮氨酸(Leu)或色氨酸(Trp)或丙氨酸(Ala)或缬氨酸(Val),87位天冬氨酸(Asp)突变为天冬酰胺(Asn)或甘氨酸(Gly)或酪氨酸(Tyr)或组氨酸(His)或缬氨酸(Val)。结论47株手术感染大肠埃希菌分离株为诺氟沙星耐药株,该细菌对多数抗菌药物产生了耐药性,gyrA基因突变是导致手术感染大肠埃希菌对抗菌药物产生耐药性的主要原因之一。因此,在治疗手术感染大肠埃希菌时应根据药敏试验结果选用抗生素。
Objective To study the mutation and drug resistance of gyrA gene of Escherichia coli in surgical infection in order to guide rational selection of antibiotics in clinical treatment. Methods 40 strains of Escherichia coli gyrA gene were isolated, PCR amplified and gene sequenced, the mutation sites were analyzed and bacterial susceptibility tests were performed. Results The results of drug susceptibility test showed that the drug resistance rates of nalidixic acid, norfloxacin and pefloxacin to 40 isolates of Escherichia coli (Norfloxacin-resistant) were all 100.0% The drug resistance rates of shaoxing, levofloxacin, ciprofloxacin and enoxacin were 90.0%, 75.0%, 75.0% and 70.0%, respectively. The rates of resistance to gatifloxacin and moxifloxacin were 15.0% and 10.0% . The gyrA gene was amplified by PCR with a size of 285bp. Sequence analysis showed that most of the mutations in this gene occurred at the 83rd and 87th of the codon-encoded amino acids. The major mutations were serine (Ser) to leu or tryptophan (Trp) (Ala) or Val (Val), Asp (Asp) to Asn or Gly or Tyr or histidine (His) ) Or valine (Val). Conclusion 47 isolates of Escherichia coli infected with surgery were norfloxacin-resistant strains. The bacteria were resistant to most antibiotics. The mutation of gyrA gene resulted in the infection of Escherichia coli with antibiotics One of the main reasons. Therefore, in the treatment of Escherichia coli infection should be based on drug susceptibility test results selected antibiotics.