炎症性肠病与肠道息肉感染致泻性大肠埃希菌实验室检测方法分析

Analysis of laboratory detection method of diarrheagenic Escherichia coli in inflammatory bowel disease and intestinal polyp infection

目的分析炎症性肠病(inflammatory bowel disease,IBD)患者和肠道息肉患者感染致泻性大肠埃希菌(diarrheagenic Escherichia coli,DEC)实验室检测方法,为该类疾病诊断提供实验室依据。方法收集2019年1月1日至2020年12月31日我院消化内科130例IBD患者(IBD组)和79例肠道息肉患者(息肉组)的大便,常规方法培养分离大肠埃希菌,用VITEK Compact 2全自动细菌分析仪和VITEK MS全自动快速微生物质谱检测系统鉴定到种,血清学和分子生物学鉴定DEC分型。结果大肠埃希菌分离率IBD组高于肠道息肉组(P=0.028)。肠道分离大肠埃希菌性别分布IBD组与息肉组比较,差异无统计学意义(P=0.216),年龄分布差异有统计学意义(P=0.023)。大肠埃希菌在麦康凯平板分解乳糖能力IBD组与息肉组比较,差异无统计学意义(P=0.112)。采用血清学和实时荧光PCR方法进行DEC分型鉴定,实时荧光PCR阳性14株,血清学阳性13株,血清学和实时荧光PCR分型同时阳性4株。血清学与实时荧光PCR法分型鉴定同时阴性29例,符合率55.78%(29/52);两种方法不一致19例,不符合率36.54%(19/52)。以实时荧光PCR分型为准,14株DEC中IBD组12株,息肉组2株,DEC分离率IBD组与息肉组比较,差异无统计学意义(P=0.279)。14株DEC均为EAEC,年龄15~59岁,呈季节散发性分布。结论IBD患者肠道大肠埃希菌分离率高于肠道息肉患者,均为EAEC,感染以中青年为主。DEC分型鉴定,传统的血清学实验结果不可靠,建议采用分子生物学方法。

Objective To analyze the laboratory detection method of diarrheagenic Escherichia coli(DEC)in patients with inflammatory bowel disease(IBD)and intestinal polyp,and to provide the laboratory basis for the diagnosis of this disease.Methods Stool samples were collected from 130 patients with IBD and 79 patients with intestinal polyps in the Department of Gastroenterology of our hospital from Jan.1st,2019 to Dec.31st,2020.Escherichia coli was cultured and isolated by conventional methods,and identified by VITEK Compact 2 automatic bacterial analyzer and VITEK MS,serology and molecular biology identified and typed of DEC.Results The isolation rate of Escherichia coli in the IBD group was higher than that in the intestinal polyp group(P=0.028).There was no significant difference in gender distribution between IBD group and polyp group(P=0.216),but there was significant difference in age distribution(P=0.023).There was no difference in lactose decomposition ability between IBD group and polyp group in MAC plate(P=0.112).Serotyping and real-time PCR were used to identify DEC,14 strains were positive by real-time PCR,13 strains were positive by serology,and 4 strains were positive by serology and real-time PCR.29 cases were negative simultaneously by serotyping and PCR,and the coincidence rate was 55.78%(29/52).19 cases were inconsistent between the two methods,and the inconsistent rate was 36.54%(19/52).Based on real-time PCR typing,among the 14 DEC strains,there were 12 strains in IBD group and 2 strains in polyp group.The isolation rate of DEC in IBD group and polyp group had no statistical significance(P=0.279).All the 14 DEC strains were EAEC,aged between 15 and 59 years old,and showed sporadic distribution in season.Conclusion The isolation rate of intestinal Escherichia coli in IBD patients was higher than that in intestinal polyp patients,and EAEC was found in all patients.The infection is mainly distributed in young and middle-aged patients.The traditional serological test results are not reliable for the identification of DEC,so molecular biological method is recommended.