WEDNESDAY, Nov. 2 (HealthDay News) -- Nearly half of 50 hospital rooms tested by researchers were colonized or infected with a multidrug-resistant bacteria, a new study says.

University of Maryland School of Medicine researchers found Acinetobacter baumannii(MDR-AB) bacteria on multiple surfaces, including bedrails, supply carts and floors. This species of bacteria, which has caused infection outbreaks in health care facilities over the last decade, can survive on surfaces for long periods of time. MDR-AB infections mainly occur in patients who are very ill, wounded or have weakened immune systems.

For the study, the researchers analyzed samples collected from 10 surfaces in each of 50 hospital rooms occupied by patients with a recent (less than two months prior to sampling) or remote (more than two months) history of MDR-AB.

The surfaces selected for sampling included bedrails, bedside table, door knob, vital sign monitor touchpad, nurse call button, sink, supply cart drawer handles, infusion pump, ventilator surface touch pad, and the floor on both sides of the bed.

The researchers found that 9.8 percent of the surface samples from 48 percent of the rooms showed evidence of MDR-AB. The surfaces most commonly contaminated were supply cart handles (20 percent), floors (16 percent), infusion pumps (14 percent), ventilator touchpads (11.4 percent), and bedrails (just over 10 percent).

These findings are a cause for concern because these surfaces are routinely touched by health care workers, the researchers said.

The study, published in the November issue of the American Journal of Infection Control, also found that patients with a recent history of MDR-AB were no more likely to contaminate their hospital room than those with a remote history.

"For patients with MDR-AB, the surrounding environment is frequently contaminated, even among patients with a remote history of MDR-AB," the researchers concluded in a journal news release. "In addition, surfaces often touched by health care workers during routine patient care are commonly contaminated and may be a source of (hospital-based) transmission. The results of this study are consistent with studies of other important hospital pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus and Clostridium difficile."

However, the study does not show which came first -- MDR-AB or environmental contamination.

Also, the researchers noted that since they conducted their study, new methods of reducing transmission of MDR-AB have helped decrease infections.

More information

The U.S. Centers for Disease Control and Prevention has more about health care-associated infections.