Carbapenemase genes and homology of Acinetobacter baumannii in two hospitals of Qingdao

Abstract:

ObjectiveTo investigate antimicrobial resistance, distribution, and carriage of carbapenemase genes of Acinetobacter baumannii(AB) from two hospitals in Qingdao.Methods145 AB isolates collected from two hospitals  (78 from hospital A，67 from hospital B) were performed antimicrobial susceptibility testing， carbapenemase genes were amplified by polymerase chain reaction (PCR); homology analysis were conducted with enterobacterial repetitive intergenic consensus (ERIC)PCR.ResultsAB from hospital A were generally resistant to 16 commonly used  antimicrobial agents， with the lowest resistant rate of 3.85% to cefoperazone/sulbactam， followed by resistance rate of 16.67%  to  minocycline， resistant rates to the other antimicrobial agents were all> 73%. AB from hospital B were generally resistant to 23 commonly used antimicrobial agents, but the resistance rates to minocycline and tigecycline were both 0,  resistance rates to amikacin and levofloxacin were 23.88% and 38.81% respectively, resistant rates to the other antimicrobial agents were all >64%. All strains carried OXA51 gene, the carriage rates of OXA23 gene in carbapenemresistant group were 86.76%(59/68) and 56.67%(34/60) in hospital A and B respectively, the difference was significant（χ2=14.53,P＜0.001）; OXA58 gene was detected  in 3 isolates in hospital A but not detected from hospital B. 145 AB strains were classified into 8 types， the major prevalence types were type A (n=71) and  E(n=37); the major prevalence types in hospital A were type A (46.15%) and  E（41.03%）,  hospital B were type A (52.24%) and C (17.91%).ConclusionAntimicrobial resistance of clinically isolated AB is serious and prevailed in two hospitals. OXA23 and  OXA51 genes play an important role in AB resistance to carbapenems.