Résumé
We investigated the epidemiological characteristics of diarrheagenic Escherichia coli (E.coli) infection in Fujian Province,providing reference for the prevention and control of diarrhea epidemic and outbreak.Yanping and Yongan areas were selected as surveillance sites from year 2010 to 2015,where 1 950 samples were collected from the sentinel hospitals,and then samples were isolated and cultured on MacConkey agar plates.Suspected strains were identified by routine and molecular diag nosis technique methods.Results were analyzed by SPSS 17.0 software package.A total of 129 strains of diarrheagenic E.coli were isolated with a total detection rate of 6.62％.The detection rates of enteropathogenic E.coli(EPEC),enterotoxigenic E.coli(ETEC) and enteroadhesive E.coli(EAEC) were 3.33％,1.64％ and 1.64％ respectively (including 61 strains of atypical EPEC,4 strains of typical EPEC,and 32 strains of ETEC and EAEC for each),while EHEC and EIEC were not found.There was no significant difference between the detection rates of male and female.All the patients were divided into five groups according to the age,and there were no significant differences between the detection rates of EPEC,EAEC and ETEC in the 5 groups.The detection rates were the highest in August and September.There was no significant difference between the detection rates of rural area and uban area.There was also no significant difference between the composition ratio of diarrheagenic E.coli (DEC) in the two surveillance sites.In conclusion,there were three kinds of DEC in Fujian Province,and EPEC was the dominant.August and September were the months with the highest detection rates.Children age less than five and adult aged 20 59 years were the high risk groups with DEC infection.More attention should be attached on the rational treatment by antibiotic for DEC.
Résumé
The emergence of atypical El Tor strains from V .cholerae in South Asia and Africa has been attributed to several outbreaks in recent decades ,however ,backgrounds of such strains in China remain exclusive .In this study ,PCR am-plification of both El Tor and classical alleles for ctxB ,tcpA ,rstR and hlyA genes was attempted in sixty-nine El Tor isolates from Fujian between 1962 to 2005 ,in addition ,some amplicons were sequence-analyzed .Thus ,the time point of atypical EVC strains in Fujian was determined ,genetic diversities of such strains were investigated .It was revealed that ctxB-Cl ,tcpA-Cl and hlyA genes were detected in O1 serogroup EVC isolates from Fujian since 1962 .Although rstR-Cl gene was solely detected in isolates between 1994 to 2000 .It was indicated by sequence analysis that atypical EVC strains from Fujian possessed a novel T→G mutation at residual 204 of the ctxB gene .Remarkably ,two novel ctxB genotypes (ctxB-10 and ctxB-11) were identified in one strain .The residual 115-C of ctxB in ctxB-11 showed characteristics of ctxB-Cl ,however ,its residual 203-T demonstra-ted characteristics of ctxB-El .This observation implied that it was common in O1 serogroup EVC strains from Fujian hybrid-ized with classical alleles since 1962 ,which would be the earliest time-point for the emergence of atypical El Tor strains hitherto in literature .Emergence of atypical El Tor strains harboring rstR-Cl in Fujian occurred since 1994 .Meanwhile ,novel mutation sites and ctxB genotypes were observed in Fujian isolates ,including diverse combination of ctxB genotypes in one strain and combination of biotype-specific sites in ctxB sequences .In summary ,molecular characterization of O 1 serogroup EVC strains from Fujian was unique and geography-associated .