| Objective:we analyzed the drug resistance and clinical characteristics of hypermucoviscous Klebsiella pneumoniae isolated from the affiliated hospital of Jiangsu university.We also studied the capsular serotype and virulence gene distribution of hypermucoviscous Klebsiella pneumoniae,and further explored the virulence characteristics of hypermucoviscous Klebsiella pneumoniae.The purpose of this study was to provide theoretical basis for clinical diagnosis and treatment of hypermucoviscous Klebsiella pneumoniae.Methods:1.The strains of Klebsiella pneumoniae were randomly collected from the microbiology department of the affiliated hospital of Jiangsu university from April 2018 to September 2019.All strains were identified by MALDI-TOF MS technology.HMKP were identified by string test.The VITEK 2-compact was used to detect the sensitivity of Klebsiella pneumoniae to 16 commonly used clinical antibiotics.2.The clinical data of patients with Klebsiella pneumoniae infection were collected by using the medical record system of our hospital.By comparing the differences in sample sources,department distribution and infection characteristics between HMKP and non-HMKP groups,the clinical characteristics of patients with HMKP infection in our hospital were summarized.3.Six capsular serotypes(K1,K2,K5,K20,K54,K57)and 9 virulence genes(rmpA,rmpA2,iucA,iroB,peg-344,terB,iutA,magA,wcaG)of Klebsiella pneumoniae were detected by PCR assay.By comparing the differences of capsular serotypes and virulence genes between HMKP and non-HMKP,the distribution of virulence genes of HMKP in our hospital was summarized.4.Serum resistance test,biofilm forming ability in vitro and mouse virulence test were used to compare the virulence difference between HMKP and non-HMKP.Results:1.103 strains of Klebsiella pneumoniae were isolated,including 44 strains of HMKP and 59 strains of non-HMKP.The detection rate of HMKP was the highest in liver abscess.In addition to the natural resistance to ampicillin,the resistance rate of HMKP to commonly used antibiotics is low.2.A total of 103 patients with Klebsiella pneumoniae infection were collected,including 44 in HMKP group and 59 in non-HMKP group.In terms of the distribution of clinical departments,HMKP patients were mainly in digestive department,while non-HMKP patients were mainly in respiratory department.In terms of infection types,community-acquired infection was dominant in HMKP patients,and hospital-acquired infection was dominant in non-HMKP patients.In terms of the composition of basic diseases,patients with HMKP are mainly diabetes,while patients with non-HMKP are mainly malignant tumors.In terms of invasive operation,mechanical ventilation,indwelling catheter and central venous catheterization are closely related to non-HMKP infection.In terms of laboratory examination,C-reactive protein in HMKP group was significantly higher than that in non-HMKP group after infection.In the use of antibiotics,the use of quinolones is closely related to the treatment of HMKP infection.3.The virulence genes detected more than 90% in 44 strains of HMKP were rmpA,iucA,iroB,peg-344,terB,iutA and wcaG.Except for wcaG gene,the proportion of other virulence genes in HMKP was significantly higher than that in non-HMKP.4.Capsular serotype was detected in 46 strains of 103 Klebsiella pneumoniae,including 37 strains of HMKP(35.92%)and 9 strains of non-HMKP(8.74%).The detection rate of capsular serotype in HMKP was significantly higher than that in nonHMKP.44 strains of HMKP were mainly K1 serotype(40.90%),and K1 serotype was mainly carried by rmpA+rmpA2+magA+wcaG+iucA+iroB+peg-344+terB+iutA,accounting for 83.32%.K2,K20,K54,K57 and unknown serotypes all take rmpA+rmpA2+wca G+iucA+iroB+peg-344+terB+iutA as the main carrying mode,and magA gene only exists in K1 serotype strains.5.Among the 95 strains of Klebsiella pneumoniae,62 strains were biofilm positive,the positive rate was 65.26%.The positive rates of biofilm formation by HMKP and non-HMKP were 54.55%(24/44)and 74.51%(38/51),but there was no significant difference between the two groups(P > 0.05).Among the samples from various sources,the positive rate of HMKP biofilm formation was the highest in liver abscess samples.6.Among 44 strains of HMKP,17 strains showed high serum sensitivity(S),nd20 strains were serum resistant(R).Among the 51 strains of non-HMKP,34 strains were serum sensitive(S),and 11 strains were serum resistant(R).HMKP was more resistant to serum,while non-HMKP was more sensitive to serum.In this study,HMKP had stronger antiserum killing ability than non-HMKP.7.By constructing the infection model of mice,the virulence differences between HMKP and non-HMKP were compared.After intraperitoneal infection,the mortality of HMKP group was significantly higher than that of non-HMKP group within 7 days(P < 0.05).After 24 hours of intraperitoneal infection,the concentration of IL-6 and TNF-α in serum of HMKP group and non-HMKP group increased significantly,and the concentration of IL-6 and TNF-α in HMKP group increased more significantly than that in non-HMKP group(P < 0.001).At the same time,there were different degrees of inflammatory changes in the lung,liver and kidney of the infected mice in the HMKP and non-HMKP groups,but the inflammatory changes in the HMKP group were more obvious than those in the non-HMKP group.Conclusions:1.The detection rate of HMKP in our hospital is high,which mainly comes from liver abscess fluid samples,mainly community-acquired infection,and diabetes is a common underlying disease.At present,the resistance rate of HMKP to commonly used clinical antibiotics is low,but there are strains resistant to carbapenem antibiotics.2.The main serotype of HMKP in our hospital is K1 capsule serotype,K1 serotype is mainly carried by 9 virulence genes,while other serotypes are mainly carried by rmpA+rmpA2+wcaG+iucA+iroB+peg-344+terB+iutA.3.The antiserum killing ability and pathogenicity of HMKP in our hospital were significantly higher than those of non-HMKP,suggesting that HMKP in our hospital has higher virulence. |
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