Detection Of Drug-Resistant Phenotypes And Virulence Genes Of Klebsiella Pneumoniae In Bloodstream Infections And Analysis Of Their Genetic Homology

Objective:To investigate the clinical distribution,resistance genes and trends in drug sensitivity of bloodstream infections with Klebsiella pneumoniae(BSI-KPN).To detect and analyze the correlation between its high mucus phenotype(HMV)and virulence genes,as well as to perform gene homology analysis.Methods:With retrospective analysis of clinical data of clinical isolates of bloodstream infections with Klebsiella pneumoniae in our hospital from January 2005 to July 2016,information on a total of 325 strains was collected by Whonet5.6,and 237 experimental strains were screened according to the strain inclusion criteria.The high mucus phenotype was detected using the pull-down test,and the main resistance genes and virulence genes were detected by PCR.Positive results were genetically sequenced,then the sequences were submitted to the Gen Bank online database and confirmed as the target genes by comparing them with the standard sequences of the target genes through the comparison tool BLAST.After multi-locus sequence typing(MLST)typing of the experimental strains,the results were analyzed using e BURST software and MEGA 6.0 software.Results:1.The experimental strains were mainly isolated from ICU(14.8%),hematology(12.2%),pediatrics(11.0%)and hepatobiliary surgery(9.7%),and their primary sites of infection were predominantly pulmonary.Drug susceptibility analysis revealed low resistance rates of experimental strains to Cefotetan,Piperacillin/Tazobactam,Cefoperazone/Sulbactam,Tobramycin,Amikacin,Tigecycline,Ciprofloxacin,Levofloxacin,and Carbapenems,all of which were less than 20.0%.The level of resistance to common antimicrobials was significantly higher in experimental strains isolated from the ICU than in non-ICU units(P<0.05).Analysis of resistance variability revealed a fluctuating trend of increasing resistance to Cephalosporins,Aminoglycosides,and Fluoroquinolone antibiotics.History of ICU transfer and infection with multi-drug resistant KPN were an independent risk factor for 14-day prognosis in patients with BSI-KPN(P<0.05),and factors such as gender,age,mode of infection,underlying disease,site of primary infection,and whether the patient underwent invasive procedures during hospitalization were associated with Statistical analysis of the 14-day prognosis revealed no significant differences.2.Among the 237 experimental strains,a total of 94 ESBLs-producing strains were identified,with a detection rate of 39.7%,and ESBLs-producing strains were mainly isolated from the ICU(17.0%)and the hematology department(12.8%).The highest detection rate was for the super broad-spectrum β-lactamase(ESBLs)class resistance gene SHV gene(70.4%),followed by the CTX-M gene(34.5%),with the detection rate of the CTX-M gene in ESBLs-producing strains being significantly higher than that of ESBLs-negative strains(P<0.05),the highest detection rate for the aminoglycoside class resistance gene was for rmt B(34.5%),and the highest detection rate for the fluoroquinolone High mucus phenotype Klebsiella pneumoniae(HMVKP)infections were predominantly middle-aged and elderly,and were associated with underlying disease,invasive manipulation and migratory spread.The detection rate of high mucus phenotype strains was 11.8%(28/237);the detection rate of podoconjugate genes was 21.9%,of which K1,K2,K20 and K54 accounted for 3.4%,10.9%,3.4% and 3.4%,respectively.The mucus phenotype gene rmp A was detected in 12.2%(29/237),of which 11 strains were positive for HMV.3.MLST typing results were mainly divided into those based on CC65(12.5%),CC17(10.6%)and CC37(6.3%)clonal clusters dominated by 110 ST phenotypes,with some degree of similarity in the resistance profile of isolates from the same CC clonal cluster.Most patients had combined underlying diseases,with malignancy,lung infection,diabetes and hepatobiliary disease being the most common.Conclusions:1.History of ICU transfer and infection with multi-drug resistant KPN were independent risk factors affecting the 14-day prognosis of patients with BSI-KPN(P<0.05).2.The drug resistance profile of Klebsiella pneumoniae in bloodstream infection was severe,with drug resistance genes mainly dominated by SHV,CTX-M,rmt B and qnr S.3.The detection rate of HMVKP was 11.8%,and the podoconjugate genes were mainly K2 type.4.MLST results showed a wide distribution of MLST types and high clonal diversity in our hospital for BSI-KPN,and there was no nosocomial outbreak of BSI-KPN.