沈阳地区致泻性大肠埃希菌的多重PCR检测及流行特征分析

Use of multiplex PCR to identify diarrheagenic Escherichia coli in the Shenyang area and an analysis of its epidemiological characteristics

目的通过致泻性大肠埃希菌（DEC）的检测和分子分型,了解沈阳地区腹泻患者的DEC发生率及流行特征。方法针对DEC毒力相关基因合成相应引物,建立多重PCR,用于检测沈阳地区2011-2014年腹泻患者粪便标本DEC。结果应用多重PCR方法检测406份腹泻标本,检出DEC 27株,检出率为6.65%。其中EPEC 2株（0.49%）、EHEC 1株（0.25%）、ETEC 4株（0.99%）、EIEC 1株（0.25%）、EAEC 19株（4.68%）,检出率以EAEC最高。27株DEC中检出astA、pic、estlb、esc V、stx1A、stx2A和invE等7种基因组合模式,以astA毒力基因占优势。0~岁、18~岁、60~岁年龄组DEC检出率分别为5.56%（1/18）、6.51%（22/338）和8.00%（4/50）,各年龄组腹泻患者DEC检出率差异无统计学意义（χ^2=0.192,P=0.908）;男、女性腹泻患者DEC检出率分别为6.39%（14/219）和6.95%（13/187）,差异无统计学意义（χ^2=0.051,P=0.822）。2012、2013和2014年DEC检出率为11.83%（11/93）、6.03%（12/199）和3.51%（4/114）,各年份DEC检出率差异无统计学意义（χ^2=5.952,P=0.051）。结论沈阳地区腹泻患者中DEC存在5种类型,以EAEC为主。多重PCR方法适用于大批量标本的DEC筛查与分离株的分型鉴定。

Objective To molecularly type diarrheagenic Escherichia coli and to ascertain its prevalence and epidemio- logical characteristics in patients with diarrhea in Shenyang. Methods Stool samples were collected from 406 patients with diarrhea in the Shenyang area from 2012--2014. Diarrheagenic Escherichia coli was detected with multiplex PCR. Results A total of 27 strains of diarrheagenic E. coli were detected with multiplex PCR. Diarrheagenic E. coli was de- tected at a rate of 6.65%. The detected strains consisted of 2 strains of EPEC （0.49%）, 1 strain of EHEC （0.25%）, 4 strains of ETEC （0.99%）, 1 strain of EIEC 1 strain （0.25%）, and 19 strains of EAEC （4.68%）. The predominant type of diarrheagenic E. coli was EAEC. Strains were tested for 7 virulence genes （astA, pic, estlb, esc V, stxlA, stx2A, and invE）. The virulence gene that was most prevalent was astA. By age group, diarrheagenic E. coli was detected in 5.56o/oo of individuals ages 0--17 （1/18）, in 6.51% of individuals ages 18--59 （22/338）, and in 8.00% of individuals age 60 and over （4/50）. By sex, diarrheagenic E. coil was detected in 6.39% of males （14/219） and 6.95% of females （13/ 187）. By year, diarrheagenic E. coli was detected at a rate of 11.83% （11/93） in 2012, at a rate of 6.03% （12/199） in 2013, and at a rate of 3.51% （4/114） in 2014. There were no significant differences the rate of detection of diarrheagenic E. coli by sex, age group, or year （P〉0.05）. Conclusion Diarrheagenic E. coli was detected at a low rate in Sheny- ang （6.65%）. Of the five types of diarrheagenic E. coli in the Shenyang area, EAEC was the most prevalent. Multiplex PCR is suitable for detection and molecular typing of diarrheagenic E. coli in samples from patients with diarrhea.