Transfer Of Sul Gene From Porcine Escherichia Coli To Human Stenotrophomonas Maltophilia

Stenotrophomonas maltophilia is a common opportunistic pathogen,and is increasingly resistant tosulfonamides which are the first-choice therapeutic agents.It is more difficult to treat clinical infection.Genesul is its main resistance gene tosulfonamides.The purpose of this study is to investigate the drug resistance of pig-derived Escherichia coli tosulfonamides and the prevalence of drug resistance genes in Guizhou Province,to explore the expression differences of drug resistance genes?sul?carried by pig-derived Escherichia coli under different drug concentrations,and to explore whether the drug resistance genes?sul?of pig-derived Escherichia coli can be transferred to human-derived S.maltophilia,so as to provide guidance for the rational use of antibacterial drugs in Guizhou pig farms and help to find methods to treat human-derived S.maltophilia infection.The results are as follows:1.The trace broth dilution method of American Clinical Laboratory Standa rdization Committee?CLSI?was used in the investigation to detect the drug re sistance of 274 strains of Escherichia coli isolated from large-scale pig farms i n 6 regions of Guizhou province tosulfonamides.The results showed that the drug resistance rates of 274 strains of E.coli to compoundsulfamethoxazole,sulf adiazine,sulfamonomethoxine,sulfamethazine andsulfathiazole were 79.2%,93.43%,96.72%,94.53%and 82.12%respectively.The tested bacteria showed drug resistance to compoundsulfamethoxazole with MIC₅₀0 and MIC₉₀0 of 8/152?g/m l.It is resistant tosulfamethazine andsulfathiazole with MIC₅₀0 of 1024?g/mL a nd 2048?g/mL respectively,and MIC₉₀0 of 2048?g/ml respectively.The drug r esistance tosulfadiazine andsulfamonomethoxine was moderate,with MIC₅₀0 and MIC₉₀0 of 2048?g/mL and 4096?g/mL respectively.2.The carriers ofsul1,sul2 andsul3 to 274 strains of E.coli from pigs were detected by PCR.The results showed that the total detection rate of the three drug resistance genes was 86.13%,of whichsul3 was the highest?86.13%?,followed bysul1?48.54%?andsul2?36.86%?.The detection rate of drug-resistant bacteria carrying single drug resistance gene was 35.76%,of whichsul3 was the highest?29.20%?,and the detection rate of double drug resistance gene was 29.56%.The detection rate of triple resistance gene was 13.87%.The results of correlation analysis between drug resistance phenotype and drug resistance genes showed that the detection rate ofsulfonamides resistance genes was positively correlated with their resistance tosulfonamides.3.The transfer ofsul1,sul2 andsul3 between porcine E.coli and human maltophilia was studied by transformation transfer test and conjugation transfer test.The results showed that the MIC value of the transformant of the successfully transformed human S.maltophilia increased by 8-64 times tosulfanilamide drugs,changing from sensitive to highly resistant.The conjugates of human S.maltophilia showed an increase of 8⁶4 times in MIC value tosulfanilamide drugs respectively,changing from sensitive to moderate drug resistance,and the conjugation transfer frequency was 23×10^-2.sul1 andsul2 of Escherichia coli from pigs were detected in transformants.sul2 andsul3 of pig-derived E.coli were detected in conjugates,which confirmed that the drug resistance of animal-derived E.coli tosulfonamides can be transferred to human-derived S.maltophilia through transformation and conjugation.4.Fluorescence quantitative PCR was used to detect the expression of the same strain of bacteria after 12h treatment withsulfadiazine at different concentrations.The results showed thatsul2 was expressed in a low amount in the absence of drugs,and its expression increased with the increase of drug concentration.However,sul1andsul3 showed the highest expression in the absence of drug treatment,and their expression decreased with the increase of drug concentration.This indicates that the expression ofsul2 may be closely related to bacterial drug resistance.The expression ofsul gene in the same strain showed the trend ofsul2>sul3>sul1.Conclusion:E.coli from pigs in Guizhou province has general drug resistance to fivesulfonamides,and the detection rate ofsulfonamide drug resistance genes are relatively high,withsul3 as the main drug-resistant gene,but the drug resistance tosulfonamides is closely related tosul2.sulfonamides resistance genes of E.coli from pigs can be transferred to human S.maltophilia through conjugation and transformation.