Nancy A. Melville

June 08, 2011

June 8, 2011 (Milan, Italy) — A comparison of 2 novel hospital-room decontamination methods — hydrogen peroxide (HP) vapor and an ultraviolet C (UVC) light process — shows that the former is more effective in eradicating bacteria than the latter, according to a study presented here at the 21st European Congress of Clinical Microbiology and Infectious Diseases.

Both decontamination methods have gained attention in recent years, as rates of hospital-acquired bacterial infections rise, said the study's lead author, Nancy L. Havill, MT, from the Hospital of Saint Raphael, in New Haven, Connecticut.

"Hydrogen peroxide vapor is an [Environmental Protection Agency]–registered sporicidal with proven in vitro and in situ efficacy against nosocomial pathogens," she explained. "It is useful in outbreak remediation and has been linked to reductions in hospital-acquired infections."

"Ultraviolet light has, meanwhile, been proven to have microbiological efficacy in vitro and has been shown to reduce contamination with nosocomial pathogens in situ," she noted.

In the study, the researchers from the Hospital of Saint Raphael decontaminated 15 patient rooms of varying shapes and sizes twice; there were at least 2 months between decontamination sessions (range, 11 to 17 weeks). Rooms were decontaminated once using HP vapor (Bioquell) and once using UVC light (Tru-D, Lumalier Corp.).

Five high-touch sites were tested for the presence of bacteria before and after each decontamination process.

Aerobic colony counts were determined for each site. In addition, Clostridium difficile and Geobacillus stearothermophilus were placed in discs at 5 sites in the patient rooms prior to decontamination.

Of the 75 sites sampled, 70 yielded aerobic growth in rooms prior to HP vapor decontamination; after decontamination, 65 of 70 were negative.

In the rooms treated with UVC light, all 68 sites yielded aerobic growth prior to treatment; after treatment, 35 of 68 were negative.

Of the 5 high-touch sites, 87% to 100% were negative after HP vapor decontamination, and 9% to 87% were negative after UVC light decontamination.

HP vapor treatment yielded a 6-log reduction for all 5 discs, compared with the median 2-log reduction after UVC light treatment.

Areas in the rooms that were not fully lit were less likely to be decontaminated with UVC light.

After HP vapor treatment, none of the biological indicators grew; after UVC treatment, 71% to 100% grew, depending on the density of bacterial growth in the discs at placement (P < .0001).

The findings are particularly significant. Mounting evidence indicates that standard decontamination methods for hospital patient rooms are not up to the task of safely eliminating all bacteria left behind by infected patients, said coauthor John M. Boyce, MD, chief of the infectious diseases section at the Hospital of Saint Raphael, and clinical professor of medicine at Yale University School of Medicine in New Haven, Connecticut.

"There is increasing evidence that inadequately cleaned hospital rooms put the next patient at risk of acquiring resistant bacteria that are still left in the room," he noted.

"Even if the person previously in the room wasn't severely ill with an organism, he/she is nevertheless spreading it all around and putting the next person using the room at risk."

The Hospital of Saint Raphael implemented the HP vapor system several years ago as part of a 10-month trial, in collaboration with the Centers for Disease Control and Prevention. This was the first trial of this technology in a hospital setting in the United States.

"There had been a new epidemic strain of C difficile causing a lot of illness, surgeries, and some deaths around the country. In our hospital, we started to see many more patients with severe disease," Dr. Boyce explained.

"Even though we had implemented most of the conventional recommended measures, it didn't seem like our rates were coming down to what they had been. We decided to try a new way of preventing transmission of C difficile, and we turned to hydrogen peroxide vapor," he added.

He noted that although the HP vapor is more effective against aerobic bacteria, both it and UVC light have merits, and the latter might be more convenient for some centers.

"With the [UVC] mobile unit, you just wheel it into the room and close the door. There's a wireless unit that lets you turn on the device from outside the room," he explained.

The machine delivers a preset amount of UVC light to the room's surfaces, and turns itself off when its sensors indicate that it has delivered the required amount of decontamination.

The HP vapor system, in contrast, requires that users seal the door and air vents in the room, and it might require more training for the operators.

Both systems appear to offer improvement over conventional decontamination methods, which most hospitals need, Dr. Boyce said.

The benefit of these 2 systems is that "both provide a greater certainty that the number of organisms in the room has been significantly reduced; with housekeepers, there are concerns such as constant staff turnover, and challenges for housekeepers in doing all that they need to do in the time allotted," he explained.

Dr. Havill noted that the study's limitations include the fact that the research was conducted at a single hospital, the number of rooms sampled was relatively small, and relatively few sites were sampled in each room.

"We did calculate the total aerobic bacterial counts, but identification of pathogens was not performed," she noted. In addition, "the number of spores on the carrier disc and the biological indicators are much greater than would normally be on the surface in patient rooms, presenting a difficult challenge for any decontamination process."

21st European Congress of Clinical Microbiology and Infectious Diseases (ECCMID): Abstract 0141. Presented May 8, 2011.