血流感染肺炎克雷伯菌毒力基因分布及与CRISPR-CAS系统相关性研究

Distribution of virulence gene of Klebsiella pneumoniae in blood stream infection and its correlation with CRISPR-CAS system

目的分析该院血流感染阳性肺炎克雷伯菌的常见荚膜血清型和毒力基因分布特征,探讨毒力基因与成簇的规律间隔的短回文重复序列及其相关序列(CRISPR-CAS)系统的相关性。方法收集Bac T/ALERT 3D全自动培养仪报告阳性的血培养瓶并经鉴定为肺炎克雷伯菌61株,运用纸片扩散法和Vitek-compact2仪器法检测菌株对临床常用抗生素的敏感性,用拉丝实验筛选高黏液型肺炎克雷伯菌,聚合酶链式反应(PCR)检测6种常见荚膜血清型(K1、K2、K5、K20、K54、K57)、7种毒力相关基因(rmpA、aerobactin、alls、Kfu、wcaG、magA、fimH)及3种CRISPR-CAS系统基因(CRISPR-1、CRISPR-2、CAS1)。结果荚膜血清型以K1、K2型为主,检出率分别是19.7%、13.1%。K5、K20、K57各检出1例,未检出K54型。毒力基因rmpA、aerobactin、alls、Kfu、wcaG、magA、fimH检出率分别是32.8%、23.0%、9.8%、31.1%、19.7%、19.7%、98.4%。高黏液表型筛选出14株。CRISPR-CAS系统阳性检出11株,检出率为18%,与CRISPR-CAS系统阴性菌株相比,其毒力基因携带率高,经χ~2检验,差异有统计学意义(P<0.05)。结论血流感染肺炎克雷伯菌荚膜血清型以K1、K2为主,毒力基因主要存在于表型为高黏液型的菌株,CRISPR-CAS系统阳性菌株毒力基因携带率高。

Objective To analyze the distribution characteristics of common capsular serotypes and virulence genes of Klebsiella pneumoniae with positive blood flow infection in the First Affiliated Hospital of Anhui Medical University,and to explore the correlation between virulence genes and CRISPR-CAS system.Methods 61 strains of Klebsiella pneumoniae were collected from blood culture bottles and identified as Klebsiella pneumoniae.The susceptibility of Klebsiella pneumoniae to commonly used antibiotics was detected by disk diffusion method and ViteK-compact 2 instrument.Klebsiella pneumoniae with high mucus type were screened by wire drawing test.Six common capsular serotypes(K1,K2,K5,K20,K54,K57),seven virulence-related genes(rmpA,aerobactin,alls,Kfu,wcaG,magA,fimH)and three CRISPR-CAS system genes(CRISPR-1,CRISPR-2,CAS1)were detected by polymerase chain reaction(PCR).Results The serotypes of capsule were mainly K1 and K2,and the detection rates were 19.7%and 13.1%respectively.K5,K20 and K57 serotypes were detected in one case while K54 serotypes were not detected.The detection rates of virulence genes rmpA,aerobactin,alls,Kfu,wcaG,magA and fimH were 32.8%,23.0%,9.8%,31.1%,19.7%,19.7%and 98.4%,respectively.14 strains were screened for high mucus phenotype.11 strains were detected as positive by CRISPR-CAS system and the detection rate was 18%.Compared with the negative strains of CRISPR-CAS system,the virulence gene carrying rate of CRISPR-CAS system was higher,and the difference was statistically significant byχ~2 test(P<0.05).Conclusion K1 and K2 are the main serotypes of Klebsiella pneumoniae.The virulence genes mainly exist in the strains with high mucus phenotype.The virulence gene carrying rate of CRISPR-CAS positive strains is high.