I have a number of anecdotal studies going on whenever I go to the supermarket, a restaurant, a baby doctor, and other places.

When we go to a roadhouse-style restaurant, I often watch the servers clean the table with some sort of cloth, and I’ll ask, what is the cloth cleaned with or soaked in? They usually point to some sorta sanitary solution, but aren’t too knowledgeable about how often it’s changed or cleaned. Same with those aprons the chefs are always wiping their hands on – I have dreams of large sample sizes.

The U.K. Health Protection Agency does have some resources so set about to sample those clothes used to wipe down tables in restaurants and takeaways and found they are often contaminated with E coli, listeria and other potentially dangerous bacteria.

The Guardian reports that cloths used to clean surfaces where food is prepared need to be changed regularly or thoroughly disinfected to prevent the growth of bacteria that can cause food poisoning.

HPA researchers sampled 133 cloths used for cleaning in 120 restaurants and takeaways in the north-east of England. They told the HPA’s annual conference at the University of Warwick today that 56% of the cloths contained unacceptable levels of bacteria. The most common were enterobacteriaceae (found on 86 cloths) E coli (21), Staphylococcus aureus (six) and listeria (five).

Only a third of restaurant kitchens (32%) were following the recommendation to use disposable cloths and change them regularly. The remainder had reusable cloths; in 15% of the kitchens, staff were unsure how often they were replaced.

John Harford, of the HPA’s food, water and environmental microbiology laboratory, said there was no reason to suppose restaurant kitchens in the north-east operated differently from those elsewhere in the country. He pointed to the potentially serious consequences for those eating food in or from such restaurants, adding,

"We have had certain outbreaks of food poisoning at a restaurant where we have isolated salmonella from the person who has eaten the meal and we have found salmonella on the cloth in the kitchen as well.”

While most restaurants disinfected their reusable cloths every 10 to 24 hours, a number of restaurants left it longer than 24 hours and some did not know how often their cloths were disinfected.