Research On Drug Resistant Genes Of Plasmids In Multi-drug Resistant Acinetobacter Baumannii And Infective Chinese Herbals

Objective:In order to provide the theoretic evidences for treating the clinical infections caused by Acinetobacter banmannii isolates, we monitored the nosocomial infection situation of Acinetobacter baumannii. At the same time,we discussed the association of the plasmids and class 1 integrons in the plasmids with the resistance of Acinetobacter baumannii isolates to interpret the resistance mechanisms of this bacteria. In addition, we study on antibacterial activity in vitro of ethanol-extract of 20 common herbals against multiple drug-resistant bacteria and the influence on the conjugation experiments.Methods:1.The distribution of clinic isolates and screening of drug resistant isolates: Bacteria and their MICs of antimicrobial susceptibility were identified by VITEK analytic instrument from March to September,2009.2.We extracted the plasmids using Promega kit.3.PCR and DNA sequencing were used to check the resistant genes and I integrons of Acinetobacter baumannii plasmids.Sequencing was carried out.These experiments were used to study the relationship between the plasmids and the resistance of Acinetobacter baumannii.A.A. baumannii (number 10688) isolated was used as a donor,which harbored blaTEM-1, blaPER-1,blaOXA-23, blaIMP-1 and class 1 integrons and were resistant to all antibiotics tested.E.coil ATCC25922 was used as recipient to which the drug resistant genes were transmitted by the way of conjugation.We want to analysis the drug resistant,genetypes and the stability of conjugant to investigate the role of resistant plasmids in the transmission of drug resistance.5.To screen effective Chinese herbs aganist Acinetobacter baumannii and to observe the influence on the conjugation experiments.Result:1. A total of 2948 isolates was separated from March to September of 2009,in which Gram-positive and Gram-negative strains accouted for 25% and 75% respectively.The main G+microorganisms included Stap.aureus and Stap.hemolyticus et al.The main G- microorganisms included A.baumannii.P.aerugiinosa et al.Samlples were mainly isolated from sputum(44.1%), urine(26.4%), and blood(7.5%);and were mainly isolated from respiratory internal medicine(11.13%)and intensive care unit(8.92%).In the G+microorganisms,MRSA accouted for 56.87%.HLAR of E.faecium accouted for 86.79%.G+microorganisms were sensitive to glycopeptides. In the G- microorganisms, enterobacterium were sensitive to Amikancin,Imipenem and Piperacillin/Tazobactam. The extended spectrumβ-lactamase(ESBL) producing E.coli and K.pneumoniae accounted for 73.21%,50% respectively.The resistant rates of A.baumannii to Ampicillin/sulbatam, Piperacillin/Tazobactam, Aztreonam, Imipenem, Cefotetan were 49.77%,53.17%,96.8%,38.22%,99.54% respectively. They were higher than other aeras commonly.The resistant rates of P.aeruginosa to commonly used antibiotics tends to increase.We collected 71 isolates Acinelobacter baumannii resistant to multi-drug.2.The OXA-58,QnrA, VIM-2 genes were not detected in any of the isolates tested. Among tested 71 A.baumanniii olates.69(97.2%),43(60.6%),63(88.7%), 46(64.8%)were positive for blaTEM-1,blaPER-1,blaoxA-23, blaIMP-1.24(33.8%) isolates carried 4 genetypes simultaneously. The rate of resistant gene carried is high and all isolates harbored GyrA.3.67 (94.4%) isolates were positive for class 1 integrons.The class 1 integrons-positive isolates were MDR.4.Resistance phenotype of Ampicillin, Ampicillin/Sulbactam, Cephazolin, Ceftriaxone, Ceftizoxime, cefepime,Aztreonam and blaPER-1 and class 1 integrons of A. Baumannii as donor could be stably transferred to.E.coil ATCC25922 as recipient.5.The thanol-extract of Galla Chinensis among 20 common herbals had strong antibacterial activities and the minimum inhibitory concentration(MIC) are up to 0.195 amg/ml..They can inhibit the conjugation experiments.Conclusion:1.The production of HLAR enterococcus,MRSA, the extended spectrum B-lactamase(ESBL) producing enterobacterium,MDR,non-fermentative bacteria is high in this surveillance.The drug resistance of bacteria is increasing, we should strengthen the administration of antimicrobial use in hospitals and promote the reasonably use of antibiotics to decrease the morbidity rate and the fatality rate in hospital.2.We found many resistant genes in plasmids of Acinetobacter banmannii and many isolates carried 4 kinds of genetypes simultaneously. It is thus evident that the plasmids played an important role in the breaking out bacteria infections.3.The method of PCR could detect class 1 integrons rapidly and conveniently.We found the close relationship between class 1 integrons and multi-drug resistance of this organism.4.Plasmids harboring transferable and stably transferred blaPER-I and class 1 integrons is one of the mechanisms of MDR A Baumannii.5.Galla Chinensis have obvious bacteriostatic effect for MDR Acinetobacter baumannii.lt can provide references for the clinical treatment of MDR Acinetobacter baumannii infections.