| Objective1.To investigate the clinical infection and drug susceptibility of hypervirulent Klebsiella pneumonia(hvKP)caused by bloodstream infections,to provide clinical reference for the rational use of antibiotics for effective infection control.2.To study the capsular serotypes and virulence gene distribution of hypervirulent Klebsiella pneumoniae.3.To screen Klebsiella pneumoniae K1 and K2 serotype for the investigation of corresponding molecular characteristics.MethodsSubjects with bloodstream infection of Klebsiella pneumoniae in People’s Hospital of Quzhou were included as the object of study from January 2013 to December 2016,in combination with the sorting and screening of clinical data.The hypermucoviscosity phenotype was determined by string test.Six common capsular serotypes and nine virulence genes were detected by multiplex Polymerase Chain Reaction(PCR).Bacterial homology analysis was performed using Pulsed Field Gel Electrophoresis(PFGE)and Multilocus Sequence Typing(MLST).Independent sample t test,Rank sum test,Chi-square test and Fisher exact test were used for statistical analysis.Results1.A total of 162 strains of Klebsiella pneumoniae bloodstream infection were screened out,mainly male;53.1%were hospital-acquired infection and 46.9%were community-acquired infection.42 strains were identified to be hvKP(25.9%),and 78.6%(33/42)of them were community-acquired infections.There was a statistical difference compared to the classic Klebsiella pneumoniae(cKP)group(P<0.05).CRP showed an increased trend by laboratory test with an average of]31.44±66.33(mg/1),which was statistically different from that in the cKP group(P<0.05).In addition to hepatobiliary system disease,patients in cKP group exhibited relatively higher proportion of combined with tumor,hypertension,coronary heart disease and chronic obstructive pulmonary disease than that in hvKP group.The calculated proportions of previous medical events in cKP group were higher than those of the hvKP group,with statistical significance(P<0.05),including prior history of tumors(30.8%),invasive procedures(49.2%).Besides,the proportion of septic shock in hvKP group(31.0%)was higher than that in cKP group(15.0%)and there was a statistical difference(P<0.05).The sensitivity rate of antibacterial agents in hvKP group was significantly higher than that in cKP group,indicating significant difference(P<0.05).Among the 42 HvKP strains,4.8%(2/42)of them produced extended-spectrum β-lactamases,and 2.4%(1/42)of them produced carbapenem enzyme.2.Six common capsule serotypes were detected,and a total of 58 strains were detected.In hvKP group,K1/K2 serotypes were the main serotypes,accounting for 57.1%(24/42).In cKP group,unusual serotypes were the main serotypes,accounting for 78.3%(94/120).Nine virulence genes were detected in both groups.Among them,fimH,mrkD,and entB showed 100%detectable rates,iutA,iroN,alls,and rmpA were statistically significant in the two groups(P<0.05).3.Thirty-seven strains of K1 and K2 Klebsiella pneumoniae had a total of 9 different PFGE clusters,of which K1 was divided into 3 clusters,K2 was divided into 6 clusters.Cluster A and F were the main cluster of K1 and K2,respectively,accounting for 76.5%(13/17)and 45%(9/20),respectively.There were 8 STs according to MLST typing,including 2 STs of K1 and 6 STs of K2.Fifteen ST23 strains were detected,which was the main STs of K1,accounting for 88.2%(15/17).Ten ST65 strains were detected,which was the main STs of K2,accounting for 50%(10/20).ConclusionshvKP occur in patients with community-acquired infections,and in those combine with hepatobiliary system disease.hvKP is characterized by general sensitivity to antibiotics,easy to cause septic shock.K1/K2 serotypes are the main serotypes of hvKP,and the virulence gene carrying rate is higher than that of cKP.According to PFGE and MLST typing,there are polyclonal epidemic strains in this region.besides,ST23 of cluster A and ST65 of cluster F are the main epidemic strain of K1 and K2,respectively. |
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