Study On The Carbapenem And Integron Of Carbapenm-Resistant Acinetobacter Baumannii

Objective To investigate the distribution and drug resistance characteristics of Acinetobacter baumannii(AB)isolated from the patients in Huaibei People’s Hospital.To study the producing and distribution of carbapenemase and integrons in carbapenem-resistant Acinetobacter baumannii(CRAB).To explore the correlation between integron and multidrug resistance in AB,so as to provide guidance and help for clinical rational use of antibiotics.Materials and methods Sixty-five strains of Acinetobacter baumannii were isolated from Huaibei People’s Hospital from january 2013 to december 2013.To analyse the distribution and drug resistance in clinical isolates of Acinetobacter baumannii in our hospital.Antimicrobial susceptibility was tested by K-B disk diffusion method against piperacillin,piperacillin-tazobactam,levofloxacin,cefoperazone/shubatan,minocycline,cephalosporins,and carbapenems.Metallo-β-lactamase(MBLs)and carbapenemases were detected by EDTA disk synergy test and modified Hodge test.The carbapenemase genes were analyzed by PCR,OXA-23 and KPC-2 gene were analysised by cloning and sequencing.The transferability of carbapenemase gene resistance was ensured by conjugation experiment,part of carbapenemase gene positive was mapped to plasmid to locate it.PCR methods and sequence analysis were used to detect the distribution of integron gene.The relation between AB drug-resistance phenotype and integron is also analyzed.Results According to the feature of specimen kinds,the dominant source was sputum(73.8%),followed by secretion(10.8%),other kinds of samples accounted minority.These strains had the same department centralized trend,mainly from ICU(47.7%),nerve internal medicine(23.1%),and respiratory department(18.5%).The resistance rates of 65 isolates to piperacillin,ceftazidime,cefepime,Cefoperazone-sulbactam and minocycline were 93.8%,72.3%,73.8%,41.5% and 7.7%.Then,the resistance rates to imipenem and meropenem achieved 47.7% and 52.3%.Carbapenemases phenotypic testing results showed that the posive isolates were 28.The number of isolates detected OXA-23 and KPC-2 were 25 and 13 from 28 producing carbapenemases Ab,sequencing results showed that OXA-23 and KPC-2 were no mutation.The study indicates that positive rate of I Class integron in CRAB is 61.8%(21/34),the positive rate of carbapenem sensitive stains is 16.1%(5/31).CRAB with and without I Class integron are both insensitive to piperacillin,and the difference is statistically insignificant.Drug resistance rate to all others show statistically significant differences(P<0.05).Conclusion Acinetobacter baumanii could be insolated from many parts of the body,including respiratory tract and wounds,but mainly in the lower respiratory tract.Results indicate that the drug-resistance rate to minocycline is the lowest,then cefoperazone-sulbactam.What’s more,imipenem-resistant rate keeped a high level.The most prevalent carbapenemase-resistant was OXA-23 and KPC-2 in the hospital.OXA-24,OXA-58,IMP and VIM type were not detected.The positive rates of I Class integron among the CRAB is significantly higher than the carbapenem sensitive stains.