A study on contamination levels in hotel rooms led by the University of Houston, presented on Sunday at the American Society of Microbiology, reported that two of the most contaminated items were TV remote controls and bedside lamp switches.

Just as badly contaminated were surfaces more likely to be dirty, such as bathroom toilet seats and sinks, the study said.

Of greater concern, the study said, was that some of the highest levels of contamination were found on items on housekeepers' carts, such as sponges and mops. If these items are contaminated, they can lead to cross-contamination of rooms, making entire hotels dirtier.

The researchers sampled 18 surfaces in each hotel room, testing the total levels of bacteria and fecal bacteria on each one. Fecal bacteria was found on 81 per cent of all surfaces.

Among the cleaner surfaces in hotel rooms were bed headboards, curtain rods and bathroom door handles.

There are no regulatory limits for contamination of items in hotel rooms, the study said, but its findings suggest possible health risks to people with compromised immune systems.

The collaborative report between the University of Houston, Purdue University, and the University of South Carolina, sampled nine hotel rooms, three each in Texas, Indiana and South Carolina.

While Katie Kirsch, a recent University of Houston graduate who presented the study, admitted it had a small sample size, she hoped it would lead to a body of research that will eventually develop "more effective and efficient housekeeping practices."

Being able to identify which items would be high-risk would let housekeeping managers devote more time to cleaning them, making cleaning efforts more valuable and hotel rooms safer, Kirsch said.