The Research About The Distribution Of Integrons And Multi-antibiotics Resistance In Stenotrophomonas Maltophilia Strains

Objective:To analyze the mechanism of Stenotrophomonas maltophilia’s resistance to antibiotics, which were regularly used in clinic therapy; to evaluate the important role of3kinds of integron(Ⅰ,Ⅱ and Ⅲ) played in transmission of antibiotics resistance between Stenotrophomonas maltophilia strains; to study the relationship between integrons and Stenotrophomonas maltophilia’s sulfa-drugs resistance; to benefit Yantai District’s precaution and control of infectious diseases caused by Stenotrophomonas maltophilia.Methods:①Systematically identify51strains of Stenotrophomonas maltophilia collected from clinical samples.②Measure the minimum inhibitory concentration of17kinds of antibiotics to Stenotrophomonas maltophilia by broth microdilution antifungal susceptibility test (Mi-AFST).③Extended-spectrum-β-lactamase(ESBLs)-producne strains were confirmed by ther NCCLS phenotypic confirmatory test.④Amplify sulfa-drugs resistant gene (sull) and3kinds of integron (Ⅰ, Ⅱ and Ⅲ) by PCR with primers designed according to registrated DNA sequence in GenBank.⑤Sequence PCR product of srains with integron and blast the sequencing results in Genbank to find out what gene was included in variable domain of those integrons.⑥Evaluate the effect of integrons and sulfa-drugs resistant gene to drug resistance phenotype of Stenotrophomonas maltophilia; clarify the antibiotics resistance mechanism of Stenotrophomonas maltophilia and provide instructive suggestions to clinical drug therapy.Results:①Among those51strains of Stenotrophomonas maltophilia,41(80.39%).74.5%(41/55) infected individls aged over60, srains were collected from sputum samples,20srains from ICU(39.22%),13srains from Department of Respiratory (25.49%),6strains from Senior Cardres Ward (11.76%).②Drug Susceptibility test demonstrated that Stenotrophomonas maltophilia strains have resistance to most of regularly used antibiotics, some strains even showed resistance to over10kinds of antibiotics. But, Stenotrophomona maltophilia strains are sensitive to Minocycline, Evofloxacin, Compound sulfamethoxazole and Iprofloxacin, the sensitive rate of those drugs is98.04%,90.2%,80.4%and74.5%respectively.3kinds of compound enzyme inhibitors Piperacillin/Tazobactam, Cefoperazone/Sulbactam and Ticarcillin/Clavulanic Acid showed relatively high antibacterial ability to Stenotrophomonas maltophilia, the sensitive rate of those drugs is54.9%,62.7%and66.7%respectively.③PCR results showed that among those51strains of Stenotrophomonas maltophilia,7(13.7%) strains cotain integron I,12(23.5%) strains contain sull gene, and all the7strains cotaining integron I didn’t carry the sull gene.Conclusions:①Infections, most of them were respiratory infection, caused by Stenotrophomonas maltophilia mainly happened in ICU and Department of Respiratory. Most respiratory infection patients accompanied with some basic or low immunity disease, and most of these patients aged over60.②Stenotrophomonas maltophilia srains have resistance to most of regularly used antibiotics but were relatively sensitive to Quinolones, Cefoperazone/Sulbactam, Compound sulfamethoxazole and Ticarcillin/Clavulanic Acid.③The transmission of drug resistant genes, carried by integrons, between different strains was the major reason for the sulfa-drugs resistance of Stenotrophomonas maltophilia. The existence of integron type I and drug resistant gene sull lead to the limitation of sulfa-drugs’application.