Analysis Of The Resistant Phenotype And Genotype In Multidrug Resistant Acinetobacter Baumannii

Objective:To investigate the resistance of Acinetobacter baumannii to antibiotics and determine theβ-lactamases of the multidrug resistant A.baumannii and its drug-resistant genes and analyze the homology of the drug-resistant associated genes.Methods:The collected isolates from the hospitals in Baotou city were identified by Vitek32. Susceptibility tests were performed with the Kirby-Bauer agar diffusion method followed by whonets5.3 software.The extended-spectrump-lactamases producing strains were confirmed by agar dilution test and three dimentional test.The AmpC enzyme was detected by three dimentional test and the mentalβ-lactamases were determined by synergy test.The genes of TEM, SHV, AmpC, OXA-23, OXA-24, PER,VEB,IMP,VIM and aaeCl, aad A1,aphA1, gyrA for these strains were amplified with polymarase chain reaction(PCR) and part of them were sequenced.Pulsed-field gel electrophoresis(PFGE) was used for homologous analysis.Result:1.Over fifty Percent of the isolates were found to be resistant to the third and fourth generations of cephalosporins, SMZ, CIP, ATM, and GEN. The resistance rate to CSL is 8.2% whereas the intermediate rateis 44.8%.The resistance to IMP accounts for 2.2%, and 2 isolates are the pan-drug resistant strains.2.29 from the 31 multidrug resistant strains collected in Baotou Hospital showed AmpC enzyme activity,8 strains Produced ESBLs(but only 3 detected by K-B confirmed test) and 5 isolates produced MBL enzyme3.The genes coding for TEM-1, aacA4 and gyrA were found to be in all of the 31 multidrug resistant strains;30 strains have AmpC gene,29 strains have aacC1 and aadA1 gene;OXA-23 gene exists in 3 strains and 2 isolates have PER and aphAl gene.No SHV, VEB, IMP, VIM and OXA-24 genes were found in all isolates.4. The homologous analysis showed that 27 strains belong to one clone and no obvious difference was noted in another 2 isolates.Conclusions:l.The drug resistant strains of A.baumannii are frequently noted and the IPM resistant strains emerged in Baotou.2.AmpC is the predominent enzyme in the multidrug resistant strains.3.Three dimensional tests used to determine the ESBLs are more efficient than K-B method.4.The genes coding for AmpC, TEM-1, aacC1, aacA4 and aadA1 are prevelant in the tested area and the emergence of OXA-23 gene resistant to IPM has become a challenging problem in clinic use of antibiotics.