| Stenotrophomonas maltophilia is an important oppotunistic pathogen causing nosocomial infections.There is a tendency in S.maltophilis becoming resistant to preferred agents sulfonamides,which brings great difficulties and challenges to clinical treatment.Escherichia coli is a resident flora in humans and animals.It acts important roles in restoring and transferring drug resistance genes,and is often used as an indicator of drug resistance.Sulfa drugs are widely used in veterinary clinics due to low price and broad-spectrum and high efficiency,which leads to animal-derived bacteria producing severe resistance to sulfa drugs.Sul is the main resistance gene that mediates the resistance of bacteria to sulfonamides.Therefore,investigate whether Sul can be transferred from swine-derived E.coli to human-derived S.maltophilia,and vice versa,which is of great significance for the treatment of human S.maltophilia infection.This study collected serial swabs of swine anis,nasal cavity,and nasal cavity of breeders from large-scale swine farms in Guizhou Province,and isolated and identified swine-derived E.coli,swine-derived/human-derived S.maltophilia.S.maltophilia;micro-broth dilution method was used to investigate swine-derived E.coli,S.maltophilia and human-derived S.maltophilia from farms and medical clinics,to analyse drug resistance phenotypes correlations among these S.maltophilia strains;PCR was used to detect whether these S.maltophilia strains carry Sul,and used MEGA6 software to analyze the homology relationship of Sul in these strains and explore the correlation of Sul prevalence;transformation experiments and conjugation experiments were conducted to explore the transfer and transfer frequency of Sul transfer from swine-derived E.coli to human-derived S.maltophilia,and also compared,between swine-derived E.coli of carrying both Sul and movable genetic elements?IScp1 IS26,tnp A,tnp513,tnp U,int I1,int I2?swine-derived E.coli and pig-derived E.coli Sul that only carry the Sul but do not carry movable genetic elements?IScp1 IS26,tnp A,tnp513,tnp U,int I1,int I2?,the frequencies of transformation and conjugation of Sul from swine-derived E.coli into human-derived S.maltophilia.The results are as follows:?1?Isolated and identified 259 strains swine-derived E.coli,49 strains swine-derived S.maltophilia,and 40 strains human-derived S.maltophilia of farm's human From large-scale farms in Guizhou Province,Biochemical identification and molecular biological identification of the isolates showed that the isolates were consistent with the biological characteristics of E.coli and S.maltophilia.?2?The swine-derived E.coli showed different degrees of resistance to 7class?16 kinds?of antibiotics,drug resistance rate from low to high is IPM?13.92%?,AMC?20.25%?,PB?39.24%?,CAZ?41.77%?,EFT?51.90%?,OFLX?65.82%?,CTC?68.35%?,CN?74.68%?,ENR?74.68%?,FFC?84.81%?,AMP?93.67%?,DO?94.94%?,SXT?98.73%?,TET?100.00%?,SF?100.00%?,SPT?100.00%?;All the swine-derived E.coli were multidrug-resistant bacteria,and they were resistant to at least three or more drugs,mainly in the 6 times?46.84%?and 7 times?36.71%?strains;Drug-resistant spectrum type is mainly for the?+T+C+A+S+Q and?+A+T+C+P+S+Q,accounted for 41.77%and 36.71%of the tested strains respectively.The Sul detection rates of swine-derived E.coli were Sul1?66.67%?,Sul2?75.76%?and Sul3?73.94%?respectively.?3?The drug resistance rate of swine-derived S.maltophilia to 7 class?16kinds?of antibiotics from low to high were EFT?53.06%?,ENR?61.22%?,O FLX?65.31%?,CN?71.43%?,PB?71.43%??AMP?73.47%?,DO?73.47%?,AMC?81.63%?,SXT?85.71%?,FFC?87.76%?CTC?87.76%?,CAZ?91.84%?,SF?91.84%?,IMP?95.52%?,SPT?100.00%?,TET?100.00%?;swine-derived S.maltophilia were resista-nt to at least two or more drugs,mainly in the 6 times?30.61%?and 7 times?40.82%%?strains;Drug-resistant spectrum type is mainly for the?+A+T+C+Q+P and?+A+T+C+P+S+Q,accounted for 18.37%and 40.82%of the tested st rains respectively.The Sul detection rates of swine-derived S.maltophilia were Sul1?66.67%?,Sul2?75.76%?and Sul3?73.94%?respectively.?4?The drug resistance rate of human-derived S.maltophilia from large-scale pig farms to 7 class?16 kinds?of antibiotics from low to high were AM C?55.00%?,OFLX?55.00%?,CTC?57.50%?,ENR?60.00%?,PB?62.03%?,EFT?62.50%?,SPT?70.00%?,DO?70.00%?,FFC?72.50%?,SXT?77.50%?,EFT?80.00%?,SF?85.00%?,A MP?87.50%?,CN?87.50%?,TET?92.50%?,IMP?100.00%?;The multiple drug resistan ce rate of human-derived S.maltophilia from large-scale pig farms were 92.50%,mainly in the 4 times?22.50%?and 7 times?45.00%?strains;Drug-resistant spectrum type is mainly for the?+A+T+S and?+A+T+C+S+Q+P,accounted fo r 15.00%and 45.00%of the tested strains respectively.The Sul genes detectio n rates of human-derived S.maltophilia from large-scale pig farms were Sul1?45.45%?,Sul2?62.50%?,Sul3?42.50%?,respectively.?5?The drug resistance rate of human-derived S.maltophilia from hospital to 7 class?16 kinds?of antibiotics from low to high were DO?0.00%?,CT?0.00%?,FFC?0.00%?,SXT?8.33%?,ENR?12.50%?,OFLX?25.00%?,TET?54.17%?,SF?58.33%?,PB?62.50%?,CAZ?66.67%?,CN?75.00%?,AMC?91.67%?,IMP?100.00%?,AMP?100.00%?,EFT?100.00%?,SPT?100.00%?;The multiple drug resistance rate of human-derived S.maltophilia from hospital wre 100.00%,mainly in the 4 times?33.33%?and 5 times?33.33%?strains;Drug-resistant spectrum type is mainly for th e?+A+T+S+P,accounted for 25.00%of the tested strains.The Sul detection ra tes of human-derived S.maltophilia from hospital were Sul1?30.00%?,Sul2?63.64%?,Sul3?31.82%?,respectively.?6?In the same breeding environment,swine-derived E.coli,swine-derived S.maltophilia,and human-derived S.maltophilia of farm's human have similar drug resistance phenotypes,resistant to antibiotics commonly used in pig farm s and sensitive to antibiotics used in humans,and their Sul detection rates are s imilar also.However,the phenotypes of human-derived S.maltophilia strains fr om hospitals are quite different from those strains in the breeding environment,and human-derived S.maltophilia from hospitals have a highdrug resistance ra te to cephalosporins which are also commonly used in humanclinical practice,and they are highly sensitive to antibiotics commonly used inveterinary clinical practice.The homologous detection and analysis of Sul showed that the Sul o f swine-derived E.coli,swine-derived S.maltophilia,and human-derived S.malt ophilia of farm's human in the same breeding environment had high homology.The homology of Sul in pig farm's bacteria was higher than that human-derive d S.maltophilia in hospital human's.?7?The Sul of swine-derived E.coli can be transferred to human-derived S.maltophilia through transformation and conjugation.The transformation frequen cy is 1.5×10-5?5.3×10-5,and the conjugation frequency is 8×10-4?6.3×10-3,and the sensitivity of human-derived S.maltophilia to sulfonamides can be reduced.?8?The transfer frequency of swine-derived E.coli carry Sul and mobile ge netic elements?IScp1,IS26,tnp A,tnp513,tnp U,int I1,int I2?transfer to human-derived S.maltophilia was significantly higher than that swine-derived E.coli c arry Sul without mobile genetic elements?IScp1,IS26,tnp A,tnp513,tnp U,int I1,int I2?.Conclusion:swine-derived E.coli,swine-derived S.maltophilia,and human-derived S.maltophilia of farm's in Large-scale pig farms of Guizhou Province showed a higher level of resistance to antimicrobial agents,multiple drug resista nce is very serious,and has a similar type of drug resistance,However,human-derived S.maltophilia of hospital is sensitive to drugs not commonly used in clinical practice,Therefore,the resistance of swine bacteria is likely to be trans mitted to human bacteria.Sul involvement was significantly or very significantl y correlated with sulfanilamide drug resistance.The homology of Sul in pig fa rm's bacteria was higher than that S.maltophilia of hospital human's.It is pos sible that the drug resistance of human S.maltophilia was derived from porcin e bacteria.Therefore,the use of sulfanilamide drug mediated drug resistance in pig farms may increase the risk of treatment failure for human S.maltophilia.T he Sul of swine-derived E.coli can be transferred to human-derived S.maltophi lia through transformation and conjugation.In addition,the transfer frequency o f the strain with the mobile genetic elements detected in this paper?IScp1,IS26,tnp A,tnp513,tnp U,int I1,int I2?was higher,and the mobile genetic element s?IScp1,IS26,tnp A,tnp513,tnp U,int I1,int I2?promoted the horizontal transm ission of Sul genes. |
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