Shiga toxin-producing Escherichia coli (STECs) contamination of produce, as a result of contact with ruminant fecal material, has been associated with serious foodborne illness. Bacteriophages (phages) that infect STECs have primarily been reported to be of cattle origin. However, they likely exist in other environments or in animals that share habitats with cattle, such as goats. To explore the presence and diversity of phages specific to STEC O157 and the top six non-O157 STECs in goat-associated environments, environmental samples consisting of feces (goat and cattle) and soil samples were collected monthly for six months from an organic produce farm. A variety of phages belonging to the Myoviridae, Siphoviridae, and Podoviridae families were isolated from all goat fecal and half of the soil samples. The most commonly isolated phages belonged to Myoviridae and were lytic against STEC O103. The isolated phages had different host ranges, but collectively, showed lytic activity against O157 and the top six non-O157 STEC strains excluding O121. Two non-O157 STECs (O174: H21 and O-antigen-negative: H18) were isolated from soil and cattle feces, respectively. Although prior studies have reported that goats shed STEC into the environment, the findings of the current study suggest that goat feces may also contain lytic STEC-specific phages. The phages of goat origin have the capacity to infect STECs implicated in causing foodborne outbreaks, making them potential candidates for biocontrol pending additional characterization steps. Further work is needed to determine if the addition of goats to the farm environment could potentially reduce the presence of STECs.

Bacteriophages (or phages) specific to Shiga toxin-producing E. coli (STEC) strains are frequently isolated from animal-associated environments primarily because ruminant animals are the natural reservoir of STEC. However, little is known about these phages in produce-growing environments. The objective of this study was to determine the effects of environmental factors on the prevalence of the phages lytic against O157 and the top 6 non-O157 STEC on an organic farm.A total of 370 samples were collected from an organic farm, containing animal-active and producegrowing areas for one year. A bacterial cocktail, including non-pathogenic and pathogenic E. coli strains, was used for phage isolation. Meanwhile, culture methods and PCR were used to isolate STEC strains. Weather information was also collected for each sampling trip. Twenty-eight samples contained the phages lytic against STEC (or STEC-infecting phages), of which 26 were collected from the animal-active area. Moreover, the winter season had a higher phage prevalence than other seasons likely due to high rain precipitation. The phages belonging to the Myoviridae family and those lytic against STEC O103 were the most prevalent. One E. coli O103:H2 was isolated from a water sample where no STEC O103-infecting phages were found. Additionally, no STEC O103 was present in the samples containing STEC O103-infecting phages. The findings indicate that animal is the primary factor contributing to the prevalence of the STEC-infecting phages in the surrounding environment of the organic farm, and the presence of these phages contributes to the negative correlation with their STEC hosts.