Sporadic Detection of Escherichia coli O104:H4 Strain C227/11Φcu in the Edible Parts of Lamb’s Lettuce Cultured in Contaminated Agricultural Soil Samples

Abstract

In the current study, we demonstrate that E. coli O104:H4 strain C227/11Φcu, a derivative of the 2011 enterohemorrhagic/enteroaggregative (EHEC/EAEC) E. coli outbreak strain, migrated into the edible portion of lamb’s lettuce plants upon contamination of the surrounding soil. Seeds were surface-sterilized and cultivated on Murashige-Skoog agar or in autoclaved agricultural soil. Migration into the edible portions was investigated by inoculating the agar or soil close to the plants with 108 colony-forming units (CFU). The edible parts, which did not come into contact with the contaminated medium or soil, were quantitatively analyzed for the presence of bacteria after 2, 4 and 8 weeks. Strain C227/11Φcu could colonize lamb’s lettuce when contamination of medium or soil occurs. The highest recovery rate (27%) was found for lettuce cultivated in agar, and up to 1.6 × 103 CFU/g lettuce was detected. The recovery rate was lower for the soil samples (9% and 13.5%). Although the used contamination levels were high, migration of C227/11Φcu from the soil into the edible parts was demonstrated. This study further highlights the risk of crop plant contamination with pathogenic E. coli upon soil contamination.

Pathogens in the Food Chain: Escherichia coli Strains in Raw Milk Originating from Ewes Treated for Mastitis with Various Therapeutic Protocols

“…Additionally, other pathogenic non-O157 E. coli isolates were isolated. The "big six" serotypes (O26, O45, O103, O111, O121, O145), known for their ability to cause severe illness, were present in all groups [66,67], along with other serotypes associated with illness such as O104 and O152 [68][69][70].…”