The United Kingdom’s Health Protection Agency (HPA) has found unsatisfactory levels of bacteria–a sign of poor hygiene and a cross contamination threat—in restaurant cleaning cloths.

Half the cleaning cloths used in restaurant and take-out kitchens were found to contain unhealthy levels of bacteria, researchers told HPA’s annual conference at the University of Warwick.

A study team sampled 133 cleaning cloths from 120 eating and drinking establishments in northeast England, and found that 56 percent contained unacceptable levels of bacteria, the most common of which were Enterobacteriaceae (found on 86 cloths) E. coli (21 cloths), Staphylococcus aureus (six cloths) and Listeria (five cloths).

“This interesting study looked at a small number of premises, but the findings indicate problems with poor hygiene practices at some of these establishments. Exposure to this harmful bacteria can cause food poisoning which is unpleasant for most people but for some – particularly the very young, very old and pregnant women – it can have serious consequences, ” said Dr. Paul Cosford, executive director of health protection services at HPA.

“The HPA plays an important role in monitoring the hygiene standards at commercial premises and these worrying findings should serve as a timely reminder to all caterers to ditch the dirty dishcloths and stick to disposable ones.”

The researchers told the Health Protection 2010 conference that cleaning cloths used in restaurant kitchens and dining areas need to be changed or disinfected frequently to stop bacterial growth that could cause food poisoning.

“Any breakdown in these procedures means that bacteria can be spread from the cloths to the hands of the cleaning staff and then spread to work surfaces and equipment,” researchers said in statement.  “Where kitchens prepare both raw and ready-to-eat foods, there should be separate cloths for both areas to reduce the spread of bacteria.

Although the recommended advice for restaurants is to use disposable cloths that are changed regularly, the study found that only a third (32 per cent) of the catering premises reviewed adhered to this. The remaining two thirds (68 per cent) used re-usable cloths and 15 per cent were unsure as to how often these were replaced.

One of the most important factors in reducing the spread of bacteria around the kitchen is to use separate cloths for raw and ready-to-eat food areas but the research found that 24 cloths had been used in both areas.

The researchers also found that there was no consistent approach to disinfection of re-usable cloths or in the method of disinfection. The majority disinfected their re-usable cloths every 10-24 hours but a number left them longer than 24 hours and some didn’t know how often cloths were disinfected. 

“It’s of concern that despite recommendations to use disposable cloths the majority of restaurants we surveyed were re-using cleaning cloths and some were unaware how often they changed them,” said Dr. John Piggott, the study’s lead author from HPA’s Food, Water and Environmental Microbiology laboratory in Leeds.

“Although many disinfected their cloths using bleach or other disinfectants, soaking does not remove the food on which the bacteria grow.  The disinfectant qualities of bleach do wear off after a period of time so soaking large amounts of cloths together can result in bacteria contaminating more cloths and creating more potential problems.

“All of the premises in our study were given advice on how to practice better hygiene and they will be revisited to make sure that procedures have improved.”

The study was carried out by the HPA’s Food, Water and Environmental Microbiology laboratories and was done in collaboration with local authorities. 

Looking for Enterobacteriaceae is a commonly used assessment of general hygiene status, according to HPA.

These bacteria include species that originate from the intestinal tract of animals and humans, as well as plants and the environment. The heat processes used in food production and should be readily removed from the factory, equipment and surfaces by appropriate cleaning procedures kills all Enterobacteriaceae.

The presence of more than 10,000 of these bacteria on a cloth indicates insufficient cleaning and a potential cross contamination risk. The detection of E. coli can signify a risk that fecal pathogens are present and are another indicator of poor hygiene standards.

Staphlycoccus aureus was found in six of the cloths sampled and these bacteria have the potential to cause food poisoning. 

The presence of Listeria species was found in five cloths and can also be used as an indicator to assess the hygienic status of the cloth. Listeria is less sensitive than many other bacteria to the cleaning procedures used in food processing environments and can survive in both food-processing premises and on equipment if inappropriate hygiene measures are used.

The isolation of Listeria monocytogenes from three cloths indicates a more serious issue as these bacteria can cause serious illness. Vulnerable groups, such as pregnant women, those with an impaired immune system, the elderly, and hospital in-patients, are at particular risk of infection following exposure to low levels of listeria in food.