| Objective:Screening for recurrent urinary tract infection(RUTI)cases,collecting and identifying uropathogenic Escherichia coli(UPEC)strains.Analyze the drug sensitivity characteristics of UPEC strains and provide assistance for clinical treatment of RUTI.Analysis the molecular epidemiological and virulence characteristics of UPEC strains and their biological role in the process of causing RUTI,providing information for follow-up exploring treatment and prevention methods of RUTI.Methods:1.The WHON-ET software was used to screen RUTI cases between 2011 and 2015 from Chinese PLA General Hospital;VITEK MS was used to identify UPEC strains;VITEK sensitivity cards were used to analyze the sensitivity of UPEC strains to commonly used antimicrobial agents.2.Pulsed-field Gel Electrophoresis(PFGE)method was used to analyze the homology of UPEC strains;Multiplex PCR was used to identify the phylogenetic types of strains;Multilocus Sequence Typing(MLST)analyze according to the method recommended by the website.3.Multiplex PCR was used to analyze the virulence gene distribution of UPEC strains.The UPEC strains were analyzed for serum resistance,motility and chemotaxis,biofilm formation and cell adhesion and invasive ability according to the methods described in the relevant literature.Serum resistance and cell adhesion and invasiveness results of UPEC strains showed by colony counting.The ability of motility and chemotaxis ability was been assessed by measured the growth diameter of colonies,and the ability to form biofilms determined by the OD value of each strain stained with crystal violet stain.Results:1.121 cases of RUTI cases and 311 UPEC strains were collected after screen,isolation and identification.The resistance rate of 10 antimicrobial agents were greater than 60%,and more than 75%of UPEC strains were resistant to penicillins and quinolones;while most UPEC strains were more sensitive to amikacin,piperacillin/tazobactam,cefotetan,and carbapenems.The resistance rate of UPEC strains to cephalosporins,monocyclic lactams,and nitrofurans was decreasing with age growth.Over 70%Extended-Spectrumβ-Lactamases(ESBL)UPEC strains resistant to sulfamethoxazole and tetracycline.No significant difference in drug resistance between inpatient and outpatient cases.2.After PFGE homology analysis,UPEC strains were divided into two groups,persistence infection group include 59 RUTI cases and 59 strains.Reinfection group include 32 RUTI cases and a total of 64 strains.The primary infection group and second infection group in the reinfection group were 32 strains respectively.The phylogenetic types of the persistence UPEC strains were B2,followed by D,A,and B1.The reinfection UPEC stains were A,followed by B2,D,and B1.The mainly phylogenetic types in the primary infection group UPEC strains were A,followed by D,while those in the second group were A,followed by D.The main STs of the persistence UPEC strains were ST131,followed by ST648,ST1193,and ST405.In the reinfection group UPEC strains,ST1193 was the most common STs,followed by ST167,ST405,ST648,and ST131.3.The average number of virulence factors carried by the persistence UPEC strain was 12.3,while that of the reinfection group UPEC strain was 9.5,with significant differences between the two groups(P<0.001).The serum resistance(P<0.001),cell adhesion ability(P=0.002)and invasive ability(P=0.041)of both group UPEC strains were significantly different.There was no significant difference in the mobility ability(P=0.858)and biofilm formation ability(P=0.07)between the two groups of UPEC strains.Conclusions:1.The large sample size of the UPEC strains collected in this study meets the statistical analysis requirements of the later research.In addition,if clinical conditio ns permit,Cefperazone-Sulbactam and Piperacillin/Tazobactam can be selected as the medication reference of RUTI patients;penicillins and quinolones are no longer suit able as treatment for RUTI.Cefperazone-Sulbactam,ertapenem can be used as medi cation selections for elderly RUTI patients.2.The phylogenetic types and MLST of UPEC strains indicated that the UPEC strains in the persistence infection group had stronger virulence and could provide reference for the subsequent virulence study of UPEC strains.3.The virulence characteristic results of UPEC strains showed that UPEC strains in the persistence infection group carry more virulence factors but are more sensitive to health human serum.UPEC strains first isolated from RUTI patients in the reinfection group had a similar biological characteristics as the persistence UPEC strains.The mobility and chemotaxis,biofilm formation ability of UPEC strains are not the key factors causing persistence infection of body urinary system.The persistence group UPEC strains have stronger adhesion and invasive ability to urinary tract epithelial cells may be an important prerequisite for the urinary system persistence infection. |
