Objective To investigate the epidemiological status and molecular characteristics of diarrheagenic Escherichia coli(DEC)infection in Xiangshan County,providing a basis for its infection surveillance and outbreak control.Methods The real-time fluores-cence quantitative PCR(qRT-PCR)was used to detect virulence genes in isolated E.coli strains.The identified DEC strains were per-formed whole genome sequencing(WGS).The sequencing data were utilized for bacterial resistance gene analysis,multilocus sequence typing(MLST),and core genome multilocus sequence typing(cgMLST).Results A total of 29 DEC strains were isolated,with a detection rate of 9.8%.Enteroaggregative E.coli(EAEC)and enterotoxigenic E.coli(ETEC)were the main strains,accounting for 51.7%and 31.1%,respectively,while enteropathogenic E.coli(EPEC)had a relatively low proportion(17.2%).Drug resistance gene analysis showed that these strains were generally resistant to multiple antibiotics such as fluoroquinolones and carbapenems.MLST typing identified 19 sequence types(STs),including one novel ST type(STcpEC1).Among them,ST117,ST2178,ST31,and ST48 were dominant types.ETEC strains were mainly concentrated in the clonal complex CC-10,while the molecular typing of EAEC and EPEC strains was more dispersed.cgMLST analysis further confirmed the genetic characteristics of different DEC strains.Conclusion DEC infections in Xiangshan County are mainly caused by EAEC,ETEC,and EPEC.These strains have abundant resistance genes.Among them,the molecular typing of EAEC and EPEC is relatively dispersed,while ETEC is concentrated in the clonal complex CC-10.

Objective To investigate the epidemiological status and molecular characteristics of diarrheagenic Escherichia coli(DEC)infection in Xiangshan County,providing a basis for its infection surveillance and outbreak control.Methods The real-time fluores-cence quantitative PCR(qRT-PCR)was used to detect virulence genes in isolated E.coli strains.The identified DEC strains were per-formed whole genome sequencing(WGS).The sequencing data were utilized for bacterial resistance gene analysis,multilocus sequence typing(MLST),and core genome multilocus sequence typing(cgMLST).Results A total of 29 DEC strains were isolated,with a detection rate of 9.8%.Enteroaggregative E.coli(EAEC)and enterotoxigenic E.coli(ETEC)were the main strains,accounting for 51.7%and 31.1%,respectively,while enteropathogenic E.coli(EPEC)had a relatively low proportion(17.2%).Drug resistance gene analysis showed that these strains were generally resistant to multiple antibiotics such as fluoroquinolones and carbapenems.MLST typing identified 19 sequence types(STs),including one novel ST type(STcpEC1).Among them,ST117,ST2178,ST31,and ST48 were dominant types.ETEC strains were mainly concentrated in the clonal complex CC-10,while the molecular typing of EAEC and EPEC strains was more dispersed.cgMLST analysis further confirmed the genetic characteristics of different DEC strains.Conclusion DEC infections in Xiangshan County are mainly caused by EAEC,ETEC,and EPEC.These strains have abundant resistance genes.Among them,the molecular typing of EAEC and EPEC is relatively dispersed,while ETEC is concentrated in the clonal complex CC-10.

OBJECTIVE： To synthesize and identify rotundic acid esters derivatives， and to evaluate in vitro antitumor activity. METHODS： Using rotundic acid as raw material， rotundic acid esters derivatives were synthesized by 28-esterification， 3β and 23-position hydroxyl group combined with acid anhydride. The structure of rotundic acid esters derivatives were identified by HRMS， 1H-NMR， 13C-NMR and physicochemical properties. The in vitro antitumor activities were evaluated by MTT assay against paclitaxel （positive control）， rotundic acid and rotundic acid esters derivatives with human cervical cancer cells HeLa， human malignant melanoma cells A375， human lung adenocarcinoma cells SPC-A1 and human liver cancer cells HepG2 （take IC50 as an indicator）. RESULTS： Totally 6 kinds of rotundic acid esters derivatives were synthesized， i.e. rotundic acid methyl ester（compound 1）， 3， 23-O-di（acetyl） rotundic acid methyl ester（compound 2）， 3， 23-O-di（propionyl） rotundic acid methyl ester（compound 3）， 3， 23-O-di（butyryl） rotundic acid methyl ester（compound 4）， 3， 23-O-di（phthaloyl） rotundic acid methyl ester（compound 5） and 3， 23-O-di（succinyl） rotundic acid methyl ester（compound 6）. Compared with paclitaxel， the antitumor activity of compound 5 and compound 6 to Hela， A375， HepG2 and SPC-A1 was similar to it， and there was no significant difference between them （P＞0.05）； the IC50 of rotuntic acid and other compounds decreased with statistical significance （P＜0.05）. CONCLUSIONS： In the study， 6 kinds of rotundic acid esters derivatives are synthesized and compound 5 and compound 6 have significant antitumor activity in vitro， which can provide reference for further study.