Study On Drug Resistance And Integrated Genes In Elderly Patients Infected With Stenotrophomonas Maltophilia

Objective: To analyze the clinical characteristics and drug resistance of elderly patients infected with Steotrophomonas maltophilia(SMA),and provide guidance for the rational use of clinical antibiotics.At the same time,the integron(int)and drug resistance genes of Steotrophomonas maltophilia in elderly patients were studied to determine the major drug resistance gene types in SMA,and to analyze the correlation between drug resistance and integrated genes,meanwhile,to provide new ideas for blocking integron transmission pathway.Thus controlling production and spread of SMA multidrug-resistant bacteria.Methods: Samples of SMA infected patients from January 2015 to June 2018 were collected from hunan provincial people's hospital.Steotrophomonas maltophilia was isolated.The first isolates were selected from strains of the same part of the same patient.The species were identified by the Mindray Tiandi Human automatic bacterial identification system.The sensitivity of the Steotrophomonas maltophilia to antibacterial drugs was determined by agar dilution susceptibility tests,and the results were judged according to the 2018 CLSI recommended standard.Polymerase chain reaction(PCR)amplification of strain DNA using primers of class ?,?,? integron,class ? integron variable region,dfrA1,qacE?1-sul1 and sul1,for class ? integron variable region amplification positive product was subjected to sequencing analysis,and the obtained sequencing results were subjected to BLAST alignment on the NCBI website.Result: Among the 334 strains of SMA,232 strains were isolated from the elderly group,accounting for 69.46%,and 102 strains were isolated from the young and middle-aged groups,accounting for 30.54%.The infection rate was 0.41% in the elderly group and 0.32% in the young and middle-aged group,and the difference in the infection rate between the two groups was statistically significant(P<0.05).The elderly group strains mainly come from the respiratory department and the stroke intensive care unit,mainly from the respiratory specimens.The drug resistance rate of the elderly group was significantly higher than that of the young and middle-aged group,and the difference was statistically significant(P<0.05).There were 79 strains resistant to three or more antibiotics in the elderly group,with a ratio of 34.05%.The DNA products of 334 strains of SMA were amplified by PCR.Among the 232 strains in the elderly group,104 strains detected class ? integron and positive rate was 44.83%.In the young and middle-aged group,10 SMA strains were detected with class ? integron and the positive rate was 9.80%.The detection rate of class ? integron in the two groups was compared,and the difference was statistically significant(p<0.05).No class ?I and class ?II was detected.Among the strain with class ? integron in the elderly group,18 strains of qacE?1-sul1,9 strains of sul1 and 3 strains of dfrA1 were detected.7 strains qacE?1-sul1 and 2 strains sul1 were detected,which did not detect class ? integron.Comparing ? class integron positive strains and negative rate of strain resistance genes in elderly group,the former is obviously higher than the latter,the difference was statistically significant(p<0.05).The dfrA1,qacE?1-sul1 and sul1 were not detected in the young and middle-aged group.In the elderly group,the detection rate of integron in the drug-resistant strains of trimethoprim/sulfamethoxazole,ceftazidime,levofloxacin,minocycline and ticacillin/clavulanic acid was significantly higher than the sensitive strains(p<0.05).The detection rate of integron and gene box in the group with more than or equal to 3 kinds of antibiotic resistance was compared with that in the group with less than 3 kinds of antibiotic resistance,the former was higher than the latter,the difference was statistically significant(p<0.05).The MIC distribution of 47 strains resistant to sulfamethoxazole/trimethoprim was analyzed,and the class ? integron and drug-resistant gene box positive strains had higher MIC,and the strains with MIC ? 8/152 ?g/ml accounted for 82.98%.In the elderly group,13 strains amplified the class ? integron variable region,including 5 strains carrying the aacA4-catB-aadA1 gene cassette,6 strains carrying ant(3??),2 strains carrying aac(6?)-Ib.Conclusion: 1.In elderly patients,the infection rate and drug resistance rate of Steotrophomonas maltophilia are higher than those of young and middle-aged patients,and the respiratory tract is the main infection site of Steotrophomonas maltophilia.2.In the elderly group,Steotrophomonas maltophilia is sensiti-v e to trimethoprim/sulfamethoxazole and minocycline,and these two drugs can be preferred in clinically empirical treatment of SMA i nfection.3.Class ? integrons and drug resistance genes increase the res-i stance of Steotrophomonas maltophilia infected in elderly patients.q acE?1-sul1,sul1 and dfrA1 are the main cause of resistance to t-rimethoprim/sulfamethoxazole.