Correlation Analysis Between The Bacterial Drug Resistance Phenotype And Its Genotype In Acinetobacter Baumannii Strains

ObjectiveThe correlation between the bacterial drug resistance phenotype characterization and its genetic in Acinetobacter Baumanni isolates were analysed to explore whether the resistance phenotype characterization could be used as the reference to judge the genetic correlation in Acinetobacter Baumanni strains,in order to provide an effective and practical tool for the prevention and control of nosocomial infection transmission caused by Acinetobacter Baumanni.MethodsThe strains of Acinetobacter Baumannii were isolated from various specimens of patients hospitalized of different clinical departments in the same hospital during July 2014 to December 2016.The susceptibility of Acinetobacter baumannii to 18 antibiotics commonly used in clinic,including Amikacin,gentamicin,etc,were tested by the Phoenix 100 automated microbiology system for identification and antimicrobial susceptibility.According to the characteristics of drug resistance spectrum,isolates were divided into sensitive and extensive drug-resistant two groups which may have genetic correlation of clones strains in the group.The resistance phenotype characterization of Acinetobacter baumannii was all the same in each group,and the strains were isolated from different clinical departments or the same department's patients whose hospitaliization time interval more than 2 months of non-repeat strains.Finally,we could use the pulsed-field gel electrophoresis(PFGE)technology and the UPGMA clustering analysis method to study whether there are genetic correlation between the resistance phenotype characterization and its clonal strain of Acinetobacter baumannii in the above two group.Results1.A total of 11 strains were found in the sensitive group,which had a natural sensitivity to the antimicrobial spectrum of Acinetobacter baumannii.The strains were resistant to cefazolin,ampicillin,aztreonam,amoxicillin/clavulanate;and sensitive to amikacin,entamicin,imipenem,meropenem,ceftazidime,cefotaxime,cefepime,piperacillin,ampicillin/sulbactam,piperacillin/tazobactam,polymyxin,cotrimoxazole,ciprofloxacin,levofloxacin and tetracycline.2.A total of 12 strains were found in the extensively drug-resistant group,which was sensitive to polymyxin only,and resistant to aminoglycosides,cephalosporins,carbapenems three or four generation cephalosporins,fluoroquinolones,beta lactamase inhibitor compound.This results were consistent with the drug resistance spectrum characteristics of the extensively drug-resistant of Acinetobacter baumannii.3.All of 23 Acinetobacter baumannii strains in the two groups were divided into 15 PFGE genotypes,with using PFGE technology and indicated by the letter A-O.Clustering analysis showed that among 11 strains of the sensitive group,the similarity between 66.3%~78.26%;among 12 strains of extensively drug-resistant group,the similarity between 81.05%~100%;and the genetic correlation of extensively drug-resistant group is higher than that of sensitive group.4.The PFGE genotype of the 11 strains in the sensitive group were completely inconsistent,suggesting that they belonged to different clone strains,and there were no genetic correlation between the resistance phenotype characterization and the clonal strain of Acinetobacter baumannii in the sensitive group.However,the PFGE genotypes of 12 strains in the extensively drug-resistant group were classified into B,E,C,and D type 4 clonal strains,suggesting that there were partial genetic correlation between the resistance phenotypes characterization and the clonal epidemic strains.5.Analysis of the data of the extensively drug-resistant group showed6.that the location and time of strains were also important factors affecting the genetic correlation between the resistance phenotype characterization and the clonal strains.Conclusions(1)The resistance phenotype characterization of Acinetobacter Baumanni was used as the reference to judge the genetic correlation of its clonal strains has limitations.It is necessary to combined with the broad-spectrum resistance characteristics,the time and location of isolates to analyze.(2)The extensively drug-resistant phenotype characterization of Acinetobacter baumannii may be related to the genetic correlation of the isolates,especially the strains isolated from the same department or the same short period.(3)Cluster analysis showed that the resistance of Acinetobacter baumannii was related to its genetic correlation,suggesting that antimicrobial selection pressure was an important factor causing the prevalence of the drug resistant clonal strains in nosocomial infection.