Researchers cultured bacteria from 100 kitchen towels after one month of use to determine both the type and amount of bacterial growth. They found that 49% of the towels exhibited growth of bacteria normally found in or on the human body.
"In this study, we investigated the potential role of kitchen towels in cross-contamination in the kitchen and various factors affecting the microbial profile and load of kitchen towels," said Susheela D. Biranjia-Hurdoyal
, senior lecturer of health sciences at the University of Mauritius and a lead author on the study presented Saturday at the annual meeting of the American Society for Microbiology
Of the 49 towels showing bacterial growth, almost three-quarters grew bacteria normally found in the intestines, such as E. coli and Enterococcus species. Another 14% grew colonies of Staphylococcus aureus, often referred to as "staph" -- a bacterium that is normally found on human skin and in the respiratory tract, according to the study.
"Those are bacteria that are concerns for foodborne illnesses," said Paul Dawson
, a food scientist and professor in the College of Agriculture, Forestry and Life Sciences at Clemson University in the United States, who was not involved in the study.
"Of course, E. coli is in the news a lot, but E. coli as a general genus and species is not a problem," Dawson added. "But there are specific types that can cause problems, like the ones recently found on romaine lettuce
Some strains of S. aureus can also produce a toxin that, if ingested, can lead to symptoms of food poisoning such as fever, vomiting and diarrhea, according to the US Centers for Disease Control and Prevention
"Staph is found on the hands and can cause foodborne infection by producing a toxin outside the body. Then you can ingest the toxin and get sick," Dawson said.
The researchers also found that the type and amount of bacteria differed based on a family's size, socioeconomic status and type of diet. Specifically, S. aureus was more likely to be found on towels from larger families and those of lower socioeconomic status, while the intestinal bacteria were more likely to be found in families that ate meat.
"Raw meat carries bacteria, and then if you throw it on the cutting board and use a towel or sponge to dry that off, it could pick that up," Dawson said. "Cutting boards and tabletops used for food prep are of concern and need to be cleaned regularly and dried."
The bacteria were also more likely to be found on wet towels than dry towels and on towels that were used for multiple purposes, such as wiping utensils, drying hands and cleaning surfaces, according to the study.
"Humid towels and multipurpose usage of towels should be discouraged," Biranjia-Hurdoyal said in a statement. "Moist towels could be very important in promoting the growth of potential pathogens responsible for food poisoning."
The findings are consistent with previous research
showing that towels and other kitchen items can be reservoirs for bacteria that cause foodborne illnesses.
"It's not a new finding that towels contain bacteria," Dawson said. "There's just a wider range of sources of possible bacteria in the kitchen."
These bacteria also tend to grow faster in warm, damp environments such as kitchen sponges, towels and drains. Therefore, people should be sure to clean and dry their kitchen towels often, according to Dawson.
"You want to change that towel every few days. If you have multiple towels, just throw one in the washer and get a new one," Dawson said. "And for sponges, microwaving them might be a better way to sanitize them than just putting antimicrobial liquid on them."
The new research also states that regular cleaning may be even more important for large families, particularly those with children, according to Biranjia-Hurdoyal.
"Bigger families with children and elderly members should be especially vigilant to hygiene in the kitchen," she said.