A study published in Eurosurveillence discusses the investigation of a prolonged outbreak of Salmonella Typhimurium associated with a restaurant. Over a period of a year, there were 82 cases (72 confirmed, 10 possible). The issue comes down to that Salmonella had built up in the drain system, and with leaks as well as potential bio-aerosols from the drain, Salmonella was able to continue transmission into the food preparation environment.
“We found the drains had failed in several places and hypothesised that a reservoir of bacteria in biofilm [15] and flooded areas in underfloor cavities may have sustained this outbreak, after repeated environmental cleaning failed. Drainage problems in one area of the kitchen led to liquid from the drains seeping into the kitchen suggesting a contamination pathway. We found isolates matching the outbreak strain on kitchen cloths, swabs from kitchen sinks, and pot wash areas suggesting contact with sinks may have provided a second contamination pathway. We also identified ineffective drain water-traps potentially allowing the movement of contaminated bio-aerosols [13]. Smoke tests demonstrated the potential for dissemination of foul air [bio-aerosols] into the kitchen.”
Leakage from drains, backflow from drains, and perhaps even bio-aerosols from drains may be a source of contamination into a food environment. It is important to put in procedures in place to prevent drain relates contamination.
Eurosurveillence
http://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2017.22.49.17-00037#f1
Surveillance and outbreak report Open Access
http://instance.metastore.ingenta.com/content/10.2807/1560-7917.ES.2017.22.49.17-00037
FoodWorld 