A study in Switzerland has identified feeding pets raw meat could be a potential source of Shiga toxin-producing E. coli for people and animals.
Giving domesticated animals raw meat-based diets (RMBDs) is becoming increasingly popular but can be the source of human Shiga toxin-producing E. coli (STEC) infections.
Researchers evaluated the occurrence of STEC in commercially available RMBDs, also known as Biologically Appropriate Raw Food (BARF), in Switzerland. Findings were published in the journal Microorganisms.
Of 59 samples, 35 tested positive by real-time PCR for the presence of Shiga toxin genes stx1 and/or stx2. STECs were recovered from 24 of the 35 samples with presumptive presence of STEC.
Issues for 9 of 10 suppliers
The level of STEC contamination in the study was higher than that found in other work looking at raw pet food in the U.S. and raw meat for dogs in the United Kingdom. Researchers said their findings provide evidence that the occurrence of STEC in raw meat-based diets may be underestimated.
From September 2018 to May 2020, researchers bought 59 RMBD products from 10 different suppliers in Switzerland or Germany. Products contained either pure muscle or pure organ meat, mixed muscle and organ meat products, or meat supplemented with plant ingredients.
Types of meat included beef, chicken, duck, quail, turkey, ostrich, horse, lamb, venison, rabbit, reindeer, moose, salmon and perch.
RMBDs containing Shiga toxin genes were detected in products from nine of 10 suppliers. Three samples contained two or more distinct STEC strains.
Shiga toxin genes were found in all six lamb samples and the two venison products and in half of the 17 beef and 15 poultry samples.
Variety of types found
In total, 20 different serotypes were identified by whole genome sequencing, including STEC O26:H11, O91:H10, O91:H14, O145:H28, O146:H21, and O146:H28. However, E. coli O157 was not found.
Genomes of strains belonging to ST33, ST442, and ST641 were compared with those of corresponding STs in the Swiss National Reference Centre for Enteropathogenic Bacteria and Listeria (NENT) database which collects STEC strains from confirmed human cases nationwide.
None of these strains clustered with a strain in the database, ruling out a direct match with any known case of human disease in Switzerland.
Researchers said the findings highlight the importance of promoting awareness among veterinary and public health agencies, RMBD suppliers, and pet owners.
“Considering the low infectious dose and potential disease severity, the high occurrence of STEC in RMBDs poses an important health risk for people handling raw pet food and those with close contact to pets fed on RMBDs,” according to the report.
Results build on a 2019 study published in the Royal Society Open Science journal by some of the same researchers assessing the microbiological quality of RMBDs in Switzerland.
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