Reduction of drug resistance and virulence of Klebsiella pneumoniae by sodium houttuyfonate and its mechanisms
OBJECTIVE To investigate the effects of Sodium houttuyfonate(SH)on drug resistance and virulence of Klebsiella pneumoniae.METHODS Klebsiella pneumoniae clinically isolated from the Fifth Affiliated Hospital of Wenzhou Medical University during 2021 to 2022 were collected.The drug resistance genes of carbapenem resist-ant Klebsiella pneumoniae(CRKP)was detected by PCR,the ST type was identified by multilocus sequence typ-ing(MLST),the minimum inhibitory concentration(MIC)of the strain to imipenem(IPM)was analyzed by mi-cro-broth dilution method,and different types of CRKP were screened by combining the results of drug resistance genes,ST typing and drug resistance phenotypes.PCR was used to detect mucus phenotype regulatory genes(rpmA and rpm A2),bacteriocin synthesis gene(iuc A),Salmonellin synthesis genes(iroB),and capsule typing gene(wzi),and the highly virulent Klebsiella pneumoniae(hvKP)with different capsule typing were screened.K-B disk method combined with micro broth dilution method was used to analyze the changes in resistance of CRKP to IPM before and after SH treatment.The changes in the virulence and mucus production of hvKP before and after the action of SH were analyzed by serum sterilization experiments and centrifugation experiments.Re-verse transcription quantitative PCR(qRT-PCR)was performed to analyze the changes in mRNA expression of carbapenem resistance genes(bla KPC,bla NDM)and virulence gene(galF).RESULTS Ten strains of CRKP were used as drug-resistant experimental strains,with high,medium and low three drug resistance phenotypes,nine ST type,carrying bla KPC-2,bla NDM-1,bla NDM-5 different drug resistance genes.Seven strains with different capsule subtypes of hvKP combination with standard hvKP(NUTH-K2044)were used as virulence test strains.The re-sults of the micro broth dilution method showed that after SH treatment,MIC of CRKP strain on IPM decreased to 1/4-1/2 of the original level,and the K-B disk method showed a significant expansion of the inhibitory zone.The results of serum bactericidal assay showed that the survival rate of hvKP in serum significantly decreased after SH treatment(P＜0.05),and centrifugation experiments found that SH inhibited the production of mucus in hvKP strains.The quantitative results of qRT-PCR showed that SH inhibited the mRNA expression of bla KPC,bla NDM,and galF genes(P＜0.05).CONCLUSION SH decreased drug resistance and virulence of Klebsiella pneumoniae by in-hibiting the expression of resistance genes and virulence genes as well as the synthesis of mucus.
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