Prevalence And Microbiological Characteristics Of Diarrheagenic Escherichia Coli In Feces Of Urban Rodent-like Animals From Six Regions In Southern China

1 ObjectiveDiarrheagenic Escherichia coli(DEC)is a class of Escherichia coli(E.coli)that causes intestinal infection,such as gastroenteritis and diarrhea.It is one of the leading pathogens of hospital-and community-associated infectious diseases throughout the world.DEC also plays a more and more important role in food-borne diseases,it has become a global public health problem and has brought great economic burden on countries all over the world.In this study,we trapped urban rodent-like animals in Guangzhou,Shenzhen,Maoming,Xiamen,Yiyang and Malipo,from October 2014 to May 2017.And we collected colorectal contents(feces)to isolate DEC from them.The aims of this study were 1)to investigate the carrier rate,virulence genes typing and antimicrobial resistance of DEC isolates from urban rodent-like animals(rat-shaped animals);2)to analyze the homology of DEC in urban rodent-like animals by PFGE cluster assays.We hope that these data could help to understand the pathogenic characteristics,the possibility of pathogen transmission,the difficulty of the disease treatment and the risk assessment of disease outbreak of DEC isolates from urban rodent-like animals.2 Methods2.1 Trapped urban rodent-like animals and their colorectal contents(feces).E.coli was isolated and identified by using biochemical approaches.2.2 Multiple PCR assays were used to test the virulence genes of E.coli to identify DEC types.2.3 Antimicrobial susceptibility of DEC was tested to obtain the resistance phenotype.2.4 PFGE was performed to analyze the genotype and compare the homology of DEC isolated from rodent-like animals from different regions.3 Results3.1 In this study,a total of 1122 urban rodent-like animals were trapped.Rattus norvegicus(60.70%)was the dominant species among all animals,followed by Suncus.murinus(25.85%).3.2 In total,we isolated 839 E.coli from colorectal contents(feces)of urban rodent-like animals.186 isolates were DECs,the positive rate was 22.17%.Including 10 EPECs,3 EAECs and 173 ETECs,the detection rate of each pathotype were 1.19%、0.36%and 20.62%,respectively,and the constituent ratio were 5.38%、1.61%and 93.01%,respectively.EHEC was not detected.3.3 EPEC and EAEC were detected only in Rattus norvegicus and Suncus murinus,ETEC were isolated in nearly all species(except for Bandicota indica s).DECs were detected in rodent-like animals from majority regions(except for Shenzhen).The detection rate of DEC from animals trapped in winter was higher than other seasons,which was 27.23%.3.4 57 DEC(30.64%)strains were drug resistant to more than one antimicrobial.Of all DEC strains,the rate of resistance to tetracycline was the highest(26.34%),followed by chloramphenicol(13.44%).The rate of resistance to cephems,fluoroquinolones and nitrofurans were all less than 5%.All of DEC strains were susceptible to penicillins,carbapenems and aminoglycosides.Eight(4.30%)DEC strains were multidrug-resistance and seven(3.76%)demonstrated ESBLs resistance.3.5 The result of PFGE showed that 87 types were detected from 91 DEC strains,and the similarity were 58.0%-100%.According to a≥90%similarity standard,it could be assembled into 11 PFGE clusters(26 DEC strains),whereas according to a≥95%similarity,it could be assembled into 7 PFGE clusters of 16 DEC strains,while according to a≥100%similarity,it would be assembled into 2 PFGE clusters of 6 DEC strains.We found that DEC isolates from rodent-like animals from different regions could be homologous strains.4 conclusionsUrban rodent-like animals could carry DEC,which are mainly ETEC,EPEC and EAEC strains.The presence of these isolates from rodent-like animals suggests that they can act as a reservoir for DEC infection.Minority DEC were resistant to more than one antimicrobial,tetracycline and chloramphenicol were the main drugs of resistance.Several multidrug-resistance or ESBLs-resistance DEC were found in this study.DEC isolates from rodent-like animals from different regions could be homologous strains.It is suggested that DEC can be transmitted among rodent-like animals and there is likely to be an outbreak.We need more information on DEC from the population to know if DEC could play a role in the circulation of disease between rodent-like animals and humans.