The study of three general hospitals run by NHS Lanarkshire found that women’s bathrooms contained fewer microbes than men’s, with female staff toilets particularly clean, while unisex and disabled (also unisex) toilets were the most contaminated. Multi-drug resistant bacteria were concentrated in patient toilets.

The findings were presented at the ESCMID Global Congress (formerly ECCMID) in Barcelona, Spain (27-30 April).

Professor Stephanie Dancer, a consultant microbiologist at NHS Lanarkshire, wanted to explore whether toilets without lids spread microbes to other surfaces in the bathroom when flushed, as well as whether some toilets are more contaminated than others.

She said: “The move to convert traditional male and female facilities to unisex facilities in some hospitals raises concern that people might be exposed to higher risks of contamination. For example, hand hygiene surveys show that women are more likely to clean their hands after bathroom use than men, so we decided to investigate which microbes were present on different surfaces in toilets and how many of them there were.”

Ten surfaces, six toilet types, three hospitals

For the study, Professor Stephane Dancer and colleagues collected samples from toilets at the three hospitals. Ten different surfaces in six types of toilets were swabbed more than four hours after cleaning, on four different days, one week apart, in each hospital. The surfaces were: hand-touch surfaces (toilet flush; handrail; tap; door handle); floor surfaces; and high sites (door tops; shelves; air vents).

The six types of toilets were: male staff, female staff, male patient, female patient, disabled, and unisex. A total of 480 samples were collected from each hospital and the aerobic bioburden (amount of bacteria and fungi) calculated for each type of surface. Background flora and healthcare pathogens were isolated and identified, and antimicrobial susceptibility testing was carried out.

The pathogens detected include: Staphylococcus aureus (which causes wound and other infections); Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae (bloodstream and urinary tract infections); Acinetobacter baumannii, Citrobacter and Serrati (bloodstream infections in compromised patients); Enterococci (urinary tract and wound infections); Burkholderia cepacia (chest infections in patients with cystic fibrosis); Pseudomonas aeruginosa and Stenotrophomonas maltophilia (chest infections and ventilator-associated pneumonia); Staphylococcus saprophyticus (common cause of urinary tract infections); and Aspergillus fungi (chest infections in immunocompromised patients).

A substantial proportion of isolated pathogens were multidrug-resistant and these organisms were concentrated in both male and female patient toilets. No MRSA was detected. Professor Dancer noted that every type of toilet in the three hospitals received the same cleaning (type and frequency) every day; nevertheless, the findings suggest that patient toilets should be cleaned more often.

Overall, floors and high surfaces yielded higher levels of aerobic bacteria and fungi than hand-touch sites. Professor Dancer said it is likely that hand-touch sites are cleaned more thoroughly than other surfaces, adding: “In contrast with hand-touch sites, floors are a major repository of dirt. Anything in the air eventually ends up on the floor, along with whatever is brought in on people’s footwear or shed from skin and clothes when they use the toilet.”

A surprising finding was that gram-negative pathogens such as E.coli, Stenotrophomonas maltophilia, and Klebsiella pneumoniae were as likely to be found on air vents, ceilings, and the top of doors as on floors.

“We think that the only logical explanation for this is that toilet-flushing aerosolises whatever is in the toilet bowl, whereupon tiny water particles carrying these organisms fly up to the ceiling and contaminate high sites,” Professor Dancer reasoned.

Female toilets had fewer microbes than male toilets. Samples from the handles inside the doors of male staff toilets had about eight times more microbes than those from the same handles in female staff toilets, and female staff toilets had the fewest microbes of all toilet types. This might be attributable to more frequent handwashing among females, the professor theorised.

Gender-neutral toilets

Gender-neutral toilets (unisex and disabled) had the highest microbial burden overall. This may reflect heavier overall use, as well as different attitudes to cleanliness between men and women, said Professor Dancer. She concluded: “Airborne microorganisms and contaminated surfaces carry a potential risk for infection. Hospital toilets should have lids, which should be closed before you flush, and patient toilets should be cleaned more frequently than other toilets.

“Single-sex and disabled toilets should be retained; with additional facilities labelled unisex and available for anyone. But based on this study’s findings, I don’t believe we should be abandoning single-sex toilets in favour of unisex toilets, since these toilets had the highest microbial burden overall.”

“None of the toilets sampled in the study had a window. I would be very interested to repeat the study in toilets with open windows providing an abundant supply of fresh air. There is no doubt everyone could do with more education on hand hygiene. The more we all understand about how to protect ourselves and others from germs, the better.”

Similar findings are likely in other hospitals, depending on the type and frequency of cleaning and how often they’re used, she added.

A poster on the study, which has not yet been submitted to a medical journal for publication, can be viewed here.