Relationship Between Siderophore Production And Virulence As Well As Carbapenem Resistance Of Klebsiella Pneumonia

Objective:Klebsiella pneumoniae?KPN?is a common conditional pathogen of nosocomial and community infections,which can cause respiratory tract,urethra and blood infections.Siderophore system is an important way for Klebsiella pneumoniae to obtain iron.At present,there is less research on the relationship between siderophore production and the virulence as well as drug resistance,and there is still controversy.In this study,124 Klebsiella pneumoniae were studied to investigate their virulence characteristics and the molecular epidemiological investigation of CRKP,and to clarify the relationship between the siderophore production and the virulence as well as carbapenem resistance of Klebsiella pneumoniae,respectively.124non-repetitive clinical isolates of Klebsiella pneumoniae from the Second Hospital of Hebei Medical University were collected.Six common serotypes of Klebsiella pneumoniae were specifically detected by PCR.Methods:1.124 clinical isolates of Klebsiella pneumoniae from the Second Hospital of Hebei Medical University were collected.Six common serotypes of Klebsiella pneumoniae,K1?magA?,K2,K5,K20,K54 and K57,were specifically detected by PCR.We used PCR to detected 6 serotypes of Klebsiella pneumonia?K1,K2,K5,K20,K54 and K57?,9 virulence genes?rmpA,rmpA2,wcaG,wabG,uge,mrkD,kfu,fimH and Alls?,4 siderophore genes?ironB,ybtS,entB and aero?,and 5 carbapenem resistance genes?blaKPC-2,blaNDM-1,blaIMP-4,blaVIM-1 and blaOXA-48?.2.The virulence characteristics of the tested bacteria were tested by string test and serum killing test.3.The phenotype of carbapenemase was screened by modified carbapenem inactivation method?mCIM?and EDTA-carbapenem inactivation method?eCIM?.4.The capacity of siderophore production of the bacteria was qualitatively tested by CAS universal plate assay and and quantitatively tested by UV-visible spectrophotometric assay.Results:1.Chi-square test results showed that K1,K2,rmpA2,rmpA,wcaG,Alls,ironB,and aerobactin genes were more common in the siderophore high production group than the low production group?P<0.05?.2.The results showed that besides entB+ybtS group,the siderophore production in entB+ybtS+aero group,entB+ybtS+ironB group and entB+ybtS+aero+ironB group were significantly higher than that in entB group.3.The anti-serum killing ability of siderophore high production group was significantly higher than that of low production group?P<0.001?.4.124 Klebsiella pneumoniae could be divided into 43 cases of high virulence positive group and 81 cases of negative group by using both rmpA/rmpA2 gene and“string test”positive strains as the basis of high virulence grouping.The siderophore-producing capacity of the two groups was compared,and it was found that the siderophore-producing capacity of the high virulence positive group was significantly higher than that of the negative group?P<0.001?.5.A total of 86 strains of carbapenem-resistant gene-positive bacteria were detected by PCR,including 76 strains of carbapenemase A(bla_KPC-2 76strains),9 strains of carbapenemase B(bla _NDM-1DM-1 8 strains,bla_IMP-4MP-4 1 strains)and1 strain carrying bla_KPC-2 and bla_NDM-1 genes simultaneously.The phenotypic results showed that the sensitivity and specificity of mCIM test were 94.2%and 94.7%.6.The resistance ratio to carbapenem of siderophore high production group was significantly lower than that of low production group?P<0.001?.Conclusions:The siderophore production of Klebsiella pneumoniae was positively correlated with virulence,and negatively with drug resistance ratio to carbapenem.In addition,this study found the existence of high virulence CRKP,suggesting that clinical work should be done to monitor and control bacterial resistance,rational use of antibiotics,and to avoid the outbreak of superbacteria.