The Preliminary Study On Molecular Epidemiology? Carbapenem Resistance Mechanism And Virulence Features In Carbapenem-resistant Klebsiella Pneumonia From The Burn Wards

Objectives The study is to investigate epidemiology,carbapenem resistance mechanism and virulence features of carbapenem-resistant Klebsiella pneumoniae(CRKP)isolated from the burn wards of Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine,and provide theoretical foundation for the prevention of nosocomial infections in burn wards,as well as clinical therapy of CRKP.Methods 1.All strains of Klebsiella pneumoniae were isolated from clinical samples in Shanghai Ruijin Hospital during 2010 to 2016,including 29 CRKP strains from burn ward from February to December in 2016.The diameters of inhibition zone of imipemen or meropenem for the above29 CRKP strains were less than 22 mm.2.Pulsed-field gel electrophoresis(PFGE)was used to show the homology of the CRKP strains.3.Semi-quantitative biofilm formation test was also used to assess the ability of biofilm formation.4.The HM phenotype of Klebsiella pneumoniae was determined by string test.5.PCR method was used to screen for the main carbapenemase genes(bla KPC?bla IMP ?bla OXA-48 and bla NDM)and Vinlence genes(K1?K2?K57?rmp A)followed by nucleotide sequencing analysis.Results 1.A total of 4564 clinical strains of Klebsiella pneumoniae including 671 CRKP were collected in Shanghai Ruijin Hospital during 2010 to 2016,of which 257 clinical strains including 97 CRKP were from burn wards.2.PFGE divided the 29 CRKP strains from burn wards into the following 4 types: A(11strains),B(10 strains),C(6 strains)and D(2 strains).3.PCR and DNA sequencing revealed that 29 strains of CRKP were all positive for carbapenemases,and respectively 22 positive for bla NDM-1?bla OXA-48 and bla KPC-2,3 positive for both bla NDM-1and bla OXA-48,2 positive for both bla KPC-2 and bla NDM-1,2 only carrying bla KPC-2.None of the strains was positive for bla IMP.25 isolates were positive by biofilm formation test.4.None of the strains was positive for HM phenotype.Of the 29 isolates,3 was positive for K2,1 was positive for rmp A.Conclusion: The detection rate of CRKP increased yearly in burn wards of Ruijin Hospital,and most of the strains were the extensively drug-resistant bacteria(XDR).The mechanism of drug resistance is complicated.Clonal spread of CRKP was observed in burn wards.Appropriate measures should be taken timely and effectively to prevent the in-hospital spread of CRKP.The virulence characteristics of CRKP and the relationships between virulence and drug resistance are still not clear.