Salmonella Outbreak Investigation Reinforces Importance of Drain Sanitation

A recent study that tracked the investigation into a Salmonella outbreak in Quebec, Canada, found that contamination in a restaurant’s drain system—potentially caused by the extinguishment of a kitchen fire—led to the spread of the pathogen.

Drains can harbor pathogens and biofilms in facilities and have been cited as the cause of a Salmonella Motevideo outbreak in Quebec, Canada. For “Investigation of a Salmonella Montevideo Outbreak Related to the Environmental Contamination of a Restaurant Kitchen Drainage System, Québec, Canada, 2020–2021,” (Journal of Food Protection, October 2023), researchers André Paradis, Marie-France Beaudet, Marianne Boisvert Moreau and Caroline Huot, documented the investigation into the outbreak that affected at least 67 people between January 1, 2020 and August 13, 2021. An epidemiological investigation that included whole genome sequencing found that 66% of cases were directly linked to a restaurant in the area.

After an initial evaluation of hygiene, food safety, cases of illness among workers and food sampling failed to establish the source of the outbreak, environmental samples showed that the restaurant’s kitchen drains were contaminated with the same strain of Salmonella Montevideo as the cases in the outbreak. Several cleaning and disinfection methods were used repeatedly. When environmental sampling at the restaurant sites was repeatedly and consecutively negative, cases in the community stopped.

Over the course of the epidemiologic investigation, public health responders learned that the restaurant had experienced an accidental fire in its kitchen before the Salmonella Montevideo outbreak began. According to the Québec City fire department’s incident report, the fire started in—and was limited to—the oven used for cooking chicken.

The authors posited that the fire in the kitchen, which required emergency response from firefighters who used a powder extinguisher first, then a water jet to contain and extinguish the flames, may have played a role in the contamination of the restaurant’s sinks and drains.

The authors concluded that, “The most plausible explanation for the origin of this outbreak remains the contamination of the drains in Restaurant A. The presence of contaminated biofilm in the restaurant’s kitchen drainage system may have had a role to play in the extended duration of this outbreak.”