Molecular characterization of diarrheagenic Escherichia coli isolated from vegetables in Argentina

The aim of this study was to investigate the prevalence of diarrheagenic E. coli strains in vegetables from the humid Pampa region, Argentina, and to determine the occurrence of serotypes and virulence genes in the isolates. A total of 373 fresh vegetable samples obtained from 41 different geographi...

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Bibliographic Details
Published in:International journal of food microbiology 2017-11, Vol.261, p.57-61
Main Authors: González, Juliana, Cadona, Jimena S., Sanz, Marcelo, Bustamante, Ana V., Sanso, A. Mariel
Format: Article
Language:English
Subjects:
Adhesins
Adhesins, Bacterial - genetics
Adhesins, Bacterial - metabolism
aEPEC
Agricultural pollution
Argentina
Bacteria
Coils
Cytotoxicity
Diarrhea - microbiology
Diarrheagenic E. coli
E coli
Escherichia coli - classification
Escherichia coli - genetics
Escherichia coli - isolation & purification
Escherichia coli - metabolism
Escherichia coli Infections - microbiology
Escherichia coli Proteins - genetics
Escherichia coli Proteins - metabolism
Food Contamination - analysis
Genes
Humans
Serogroup
Serotypes
Serotyping
Studies
Toxins
Vegetables
Vegetables - microbiology
Virulence
Virulence factors
Virulence Factors - genetics
Virulence Factors - metabolism
VTEC
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Summary:The aim of this study was to investigate the prevalence of diarrheagenic E. coli strains in vegetables from the humid Pampa region, Argentina, and to determine the occurrence of serotypes and virulence genes in the isolates. A total of 373 fresh vegetable samples obtained from 41 different geographical points were examined. E. coli was detected in 38.6% of the samples. Ten isolates could be obtained from 14 samples presumptively positive for diarrheagenic E. coli: 8 were identified as atypical Enteropathogenic E. coli (aEPEC) and 2 as Verocytotoxigenic E. coli (VTEC). Lettuce and beet were the vegetables most frequently contaminated with pathogenic E. coli. The isolates belonged to serotypes O1:H7, O28:H19, O39:H40, O86:H31, O132:H8, O139:H20, O178:H7 and O178:H19, some of which reportedly have caused human illness, and one isolate resulted non typeable. Taking into account the distribution of 16 nle genes, 7 profiles were detected. On the other hand, all tested isolates harbored the gene encoding for the adhesin HcpA. Other adhesion related genes were also identified: ecpA and elfA were detected in 90%, lpfA0113 in 60%, and ehaA in 50% of the isolates meanwhile ihaA was only observed in O178:H19 isolate. This VTEC isolate harbored, also, Cdt-V toxin and megaplasmid encoding genes such as espP, subA and epeA and exhibited a strong cytotoxic effect. These data is the first molecular E. coli report that confirms the presence of E. coli pathotypes circulating among vegetables in Argentina. Genetic characterization showed that in addition to eae or vtx genes, isolates obtained from vegetables harbored genes encoding other toxins, adhesins, and components related to the type III secretion system that could contribute to their virulence. In conclusion, this research shows that vegetables in Argentina may be the source of VTEC and EPEC infections in the community and therefore, they should be considered as vehicles for transmission of these potentially pathogenic bacteria. •Prevalence and characteristics of diarrheagenic E. coli were examined in vegetables from Argentina.•Atypical EPEC and VTEC were isolated from lettuce, beet and chard.•Diarrheagenic E. coli isolates carried virulence determinants indicating their pathogenic potential.•Some of the identified serotypes have caused human illness.•Vegetables in Argentina may be the source of VTEC and EPEC infections in the community.
ISSN:0168-1605
1879-3460
DOI:10.1016/j.ijfoodmicro.2017.09.021