Effect Of Sub-inhibitory Concentration Of Antibiotics On Virulence Gene Expression Of Hypervirulent Klebsiella Pneumoniae

Backgroud Hypervirulent Klebsiella pneumoniae(Hv KP)is a strain that has been increasing in clinical isolation in recent years.Because its colony morphology exhibits a high mucus phenotype,many scholars have shown that the Klebsiella pneumoniae colonies exhibit this high mucus phenotype as an important indicator of high-virulence Klebsiella pneumoniae.It is worth noting that in the clinical anti-infection work,the blood drug concentration entering the patient's body is affected by many factors(administration method,dose,route of administration,etc.),which often causes the strain to be in the role of sub-bacterial antibiotic.This will lead to affecting the life activities of bacteria and change their pathogenic behavior.However,more studies are currently focused on the effects of sub-inhibitory antibiotics on the formation of Klebsiella pneumoniae biofilms and drug resistance,while on high-virulence Klebsiella pneumoniae under the effect of antibiotics,there are few studies on force gene changes.Therefore,this topic focuses on this point.Objective:To study the expression level changes of virulence genes of hypervirulent Klebsiella pneumoniae under the action of antibiotics with subinhibitory concentration,and to analyze the distribution of capsule serotype?related virulence genes and the homology between strains.Methods:Disk diffusion method and vitek-compact2 instrument method were used to determine the susceptibility of the strains to common clinical antibiotics,and the MIC values of the strains to cefoxitin and amikacin were detected by broth dilution method.The serotypes of capsule(K1,K2,K5,K20,K54,K57)and virulence related genes(rmp A,aerobactin,Kfu,all S,mag A,wca G,fim H,mrk D)were detected by polymerase chain reaction(PCR).Real time fluorescence quantitative PCR(RT-PCR)was used to detect the change of the relative expression of virulence genes in 1/2MIC,1/4MIC,1/8MIC concentrations of cefoxitin and amikacin,and the difference was analyzed by SPSS software.The homology between the strains was detected by MALDI-TOF MS and ERIC-PCR.Results:A total of 57 strains of Hv KP were collected,which were sensitive to most of the commonly used antibiotics.PCR results showed that there were 17 strains of K1,21 strains of K2,2 strains of K20,8 strains of K57,and 9 strains of unknown haemorrhagic type.rmp A and aerobactin genes were all positive.17,21 and 16 strains of wca G,Kfu and mag A genes were detected respectively.fim H and mrk D were all positive.Under the action of subinhibitory concentration of cefoxitin and amikacin,the two antibiotics of three concentrations(1/2 MIC,1/4 MIC,1/8 MIC)had obvious inhibitory effects on the two virulence genes(P <0.05),and the inhibition degree of cefoxitin was the highest.The inhibitory effect of 1/2 MIC was the strongest among the three concentrations.ERIC-PCR divided 57 strains into 19 types,which were expressed by A-S.MALDI-TOF MS divided 57 strains into 3 types according to the standard of protein profile similarity?70%,which is represented by?-?.The two results are consistent,showing that the genetic relationship between the strains is far away,and the results have universal significance..Conclusions:Hv KP is highly sensitive to commonly used antibiotics.Serotypes K1 and K2 are common serotypes of Hv KP than other serotypes.The virulence gene expression of rmp A and aerobactin decreased under the action of subinhibitory concentration of cefoxitin and amikacin.