Investigations On Serotyping And Virulence Genes In Klebsiella Pneumoniae Isolated From Patients With Liver Abscess

Objective: Liver abscess is a common infectious disease in liver.Bacterial liver abscess is the most common cause of liver abscess.When human's resistance is decreased,the bacteria will easily invade the liver and cause liver abscess.For nearly two decades,Klebsiella pneumoniae has gradually become the leading cause bacteria of primary liver abscess.This article aims to investigate the drug resistance,capsular serotype distribution and the epidemic characteristics of virulence genes about Klebsiella pneumoniae causing liver abscess in the First Affiliated Hospital of China Medical University in Shenyang district from 2014 to 2017,in order to find the characteristics of virulence genes carried in different serotypes,then analyze the clinical features,treatment and prognosis of patients with such liver abscess,so to provide a scientific basis for the diagnosis,treatment and prognosis in such liver abscess.Methods: Collected seventy-five Klebsiella pneumoniaee isolates from liver's puncture sample,pus and blood in liver abscess patients who came from the First Affiliated Hospital of China Medical University during 2014 to 2017.The antibiotic resistance was tested by MIC susceptibility test.The mucoid phenotype of Klebsiella pneumoniae was determined by string test.The target genes of serotypes K1,K2,K3,K5,K16,K20,K54,K57 and virulence genes rmpA,wcaG,aerobactin,kfu,allS of Klebsiella pneumoniae were detected by Polymerase Chain Reaction.The PCR products were sequenced by Shanghai Bioengineering Company,and the target genes were confirmed by aligning the nucleic acid sequence with the Blast gene sequence.The drug sensitivity data was analyzed and processed using Whonet 5.6 software.SPSS 22.0 was used to perform ?2 test on the experimental data,and P<0.05 was considered statistically significant.We analyzed clinical information including treatment and prognosis of 75 liver abscess patients in a retrospective,monocentric study.Results: The results of drug susceptibility test of 75 strains of liver abscess Klebsiella pneumoniae showed that the antimicrobial resistance rate of piperacillin was 16%,and the resistance rates to 13 antimicrobial agents such as cephalosporins,aminoglycosides,sulfonamides,etc.were not higher than 4%.Only one strain of extended-spectrum ?-lactamases(ESBLs)was found.In 2017,the drug resistance rate of piperacillin was 16%.The serotypes were mainly K1,accounting for 62.7%,followed by K2(21.33%),while the other serotypes were K5,K20 type,K54 type and K57 type(all 2.7%).Serotype K3 and K16 were not found,and 4 strains were not belong to the 8 serotypes tested in this experiment,accounting for 5.3%.Virulence genes rmpA and aerobactin showed the highest prevalence(98.7% and 97.3%,respectively),others were kfu(68%),wcaG(66.7%),allS(57.3%).wcaG,aerobactin,kfu,allS were significantly different in different serotypes(P < 0.05).The virulence genes of different serotypes showed that the virulence genes rmpA + wcaG + aerobactin + kfu + all S were co-carriers in serotype K1,accounting for 83%.The other serotypes were mainly rmpA + aerobactin.The virulence gene wcaG was all detected K1 and K54 serotypes.The detection rate of allS in K1 serotype was 89.4%,which was rare in other serotypes.The clinical data of 75 patients with liver abscess showed that surgical drainage and antibiotic treatment meanwhile was the most common therapeutic method.The improvement rate was 88.2%.45% of patients were discharged within one week.The average hospitalization was 9.7 days.The cure rate was 9.8% and the average hospitalization was 11.7 day.11.8% of patients without drainage treatment,the improvement rate of 83.3%,the average hospitalization was 35.8 days.Conclusion: Liver abscess Klebsiella pneumoniae are mostly sensitive strains.However,the resistant strains of piperacillin have been increased in the past year,which should be paid more attention in clinic.Serotype K1 and K2 are the main type of liver abscess Klebsiella pneumoniae,and serotype K5,K20,K54 and K57 are found in Shenyang district.Virulence genes rmpA and aerobactin have the highest prevalence and mostly coexist in the liver abscess Klebsiella pneumoniae.Most virulence genes have been detected in K1 which have the strongest virulence.