Researcher Katie Kirsch from the University of Houston and colleagues checked out a handful of hotels in three US states. In each room they tested 19 surfaces, looking for aerobic bacteria and faecal matter.
They were not surprised that toilets and bathroom sinks featured highly in the contamination league, but they also found high levels of bacterial contamination on the TV remote and the bedside lamp switch.
They also discovered some of the highest levels of contamination on items carried on chambermaids' trolleys, including sponges and mops. They say because these are wheeled around hotels, they pose a risk of cross-contamination of rooms.
Surfaces with the lowest contamination included bed headboards, curtain rods and bathroom door handles.
"Hoteliers have an obligation to provide their guests with a safe and secure environment," says Katie Kirsch, who presented the results at a conference of the American Society for Microbiology. She says one of the problems lies in different cleaning standards found across the hotel industry. "The current validation method for hotel room cleanliness is a visual assessment, which has been shown to be ineffective in measuring levels of sanitation," she adds in a statement.
Dr Ron Cutler, deputy director of biomedical science at Queen Mary, University of London says he is not particularly surprised that TV remote controls emerged towards the top of the contamination list. "They're quite difficult to clean, and I don't think everybody appreciates just how well these organisms can fit into the nooks and crannies," he tells BootsWebMD.
He continues: "It's not really surprising that if you don't clean things properly you give organisms the opportunity to establish themselves; and if you eat in the same area as your TV remote, and you spread food, then it gives organisms the chance to grow."
Dr Cutler and colleagues have carried out similar studies on the spread of bacteria in the natural environment. Last year they reported finding how 92% of mobile phones were contaminated with bacteria - including E. Coli - because people were not washing their hands before making a call.
Dr Cutler says most of the organisms that the researchers found in hotels are relatively harmless. However, Katie Kirsch says they could pose a risk to health, particularly for immunocompromised individuals who are more susceptible to infection.
Dr Cutler says the hotel survey is an indicator of overall hygiene and cleanliness. "If there are high levels of faecal organisms on these instruments, it means that not only haven't they been cleaned just before they sampled it, it probably means they're not cleaned on a regular basis."
Katie Kirsch acknowledges that the US study is small, but says she hopes it could lead to a more effective way of managing hotel cleaning. "Currently, housekeepers clean 14-16 rooms per eight-hour shift, spending approximately 30 minutes on each room," she says. "Identifying high-risk items within a hotel room would allow housekeeping managers to strategically design cleaning practices and allocate time to efficiently reduce the potential health risks posed by microbial contamination in hotel rooms."
These findings were presented at a medical conference. They should be considered preliminary, as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.
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