Restaurant towels can carry pathogenic bacteria for weeks in simulated lab conditions
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Commercial restaurant workers often use sponges and microfiber towels to clean food contact surfaces, but these types of absorbent materials were found to harbor potentially pathogenic organisms for more than 2 weeks, researchers said.
“The hypothesis of our study was that cleaning tools such as sponges and wiping cloths may become contaminated with bacterial pathogens and cross-contaminate other surfaces over time,” Sujata A. Sirsat, PhD, an assistant professor at the Conrad N. Hilton College of Hotel and Restaurant Management at the University of Houston, told Healio. “There is some literature about this in the domestic kitchen context; however, there is a paucity of literature in foodservice settings.”
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Sirsat and post-doctorate fellow Zahra H. Mohammad, PhD — who conceptualized and designed the study — inoculated 18 sponges and nine microfiber towels with “a low-level cocktail” of Salmonella, Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus and dried them for 1 hour in a biosafety cabinet. They left the samples at room temperature for 20 days.
The researchers took two sponge samples and two towels samples at zero and 6 hours after inoculation and washed them with either sterile water or sanitizer solution. They repeated the experiment numerous times.
Sirsat said that they spoke with “multiple restaurant managers to learn what types of towels and sponges were used” in that setting, and they purchased the same or similar items from the restaurants’ suppliers.
They found that E. coli, Salmonella and S. aureus survived for up to 16 days on the sponges and up to 13 days on microfiber towels that were washed with sterile water — demonstrating the risk posed by those materials used in the foodservice industry, the researchers said.
They also found that sanitizer solution is ineffective at sterilizing the sponges and towels after about 4 hours.
Mohammad and Sirsat noted that about 79% of foodborne illness outbreaks are linked to inappropriate food handling and preparation in restaurants, including poor hand hygiene and cross-contamination.
Sirsat said it is unknown if specific cases of foodborne illness or outbreaks are connected to contaminated towels or sponges.
“A majority of foodborne illness goes unreported and oftentimes is hard to trace back to the original source,” she said. “This study provides tools to reduce this risk of contamination from towels and sponges.”
Mohammad, who suggested sponges are less hygienic to use than towels because their porous surfaces make them “ideal breeding grounds for bacteria,” stressed that current sanitation solutions are effective against pathogens if used correctly. The ideal way to sanitize these cleaning tools, she said, is to microwave them for approximately 1 minute.
“Microorganisms are ubiquitous, and pathogenic microorganisms can make us sick,” she added. “Therefore, proper sanitizing of kitchen cleaning tools and frequently replacing them is critical to ensure the safety of these tools and prevent cross-contamination.”
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Mohammad ZH, Sirsat SA. Survival and persistence of pathogenic bacteria on kitchen sponge and microfiber towel in restaurant and foodservice operations. Presented at: ASM Microbe; June 3-7, 2020 (virtual meeting).
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