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Public restrooms contained too many bacteria to count

IDSA 49th Annual Meeting

BOSTON — High-touch areas of public restrooms — particularly areas people touched after washing their hands — frequently contained more than 1,000 colony-forming units per milliliter of infection-causing bacteria, according to findings presented here.

Lennox Archibald, MD, PhD, of the College of Medicine at the University of Florida in Gainesville, spoke to Infectious Diseases in Children at the IDSA 49th Annual Meeting. “The six or seven bugs that we found were the ones that cause two-thirds of infections in health care centers,” he said.

The researchers aimed to fill a void in qualitative or quantitative data about bacterial contamination of surfaces likely to be touched after washing and drying hands in public restrooms. Public restroom areas included those in malls, hospitals, offices, lecture halls, conference centers, department stores, restaurants, airports and resorts.

Of the multitude of organisms recovered, the predominant gram-positive organisms recovered included Staphylococcus, Micrococcus, Bacillus and Enterococcus. Gram-negative microorganisms were mostly Enterobacteriaceae (eg, Escherichia coli, Klebsiella, Cronobacter, Leclercia, Pantoea and Serratia) or non-fermenters, according to the results.

All high-touch surfaces yielded extensive quantitative cultures. The quantity of organisms was too numerous to count in several of the restrooms. The research included a process of counting up to 1,000 colony-forming units (CFU)/milliliter. Archibald said the standard measure for “too numerous to count” is usually 250 CFU/mL.

The areas most likely to contain microorganisms that were too numerous to count included faucets, soap and paper dispenser operating levers, and the exit door handle of restaurants and aircraft restrooms.

“It is especially important to note that this was in areas people touched after they washed their hands,” he said.

This was the first phase of a three-phase study. “The first phase, which we are looking at here, was simply a microbiologic characterization,” Archibald said. “The second phase included observation of hand washing practices, including the time taken to wash and dry hands, and the third phase included information on more than 200 bathrooms representing 40 different kinds of sites. These data are forthcoming.”

The trial was conducted from December to February. The researchers cultured 18 public restrooms and four commercial aircraft. – by Rob Volansky

Disclosure: Dr. Archibald reports no relevant financial disclosures.

For more information:

• Archibald L. #314. Presented at: IDSA 49th Annual Meeting; Oct. 20-23, 2011; Boston.

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