Hydrogen peroxide fights environmental MRSA

Hydrogen peroxide vapor has been found to be an effective disinfectant against methicillin-resistant Staphylococcus aureus (MRSA) in hospitals, according to data presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy annual meeting.

When an outbreak of MRSA caused the colonization of 11 patients in a hospital in England, hydrogen peroxide vapor was used to decontaminate the ward. Previously, the ward had been free of MRSA. When culture of the minor surgical wounds of 2 patients residing in separate bays yielded MRSA, further microbiologic screening revealed that 11 to 28 patients (39%) were colonized. Environmental sampling showed extensive contamination with MRSA; 7 to 8 environmental isolates were distinguishable from the patients’ isolates.

Because of the patient load, one bay was emptied, and the patients were shuttled through it, as the other bays, side rooms, and bathrooms were closed off and decontaminated over two days. Decontamination was done with a Clarus R HPV generator. Contact time with hydrogen peroxide vapor was about two hours in each bay.

After decontamination, the hydrogen peroxide was catalytically converted to water and oxygen, leaving no toxic residues. The ward remained operational throughout the decontamination period.

In the week before decontamination 8 of 29 sites (bed rails, bed frames, lockers, bedside telephones, and mobile pharmacy computers) tested positive for MRSA. Afterward, one of the sites was still positive. They think they can be pretty sure it was recontamination, because they had three screens of the same sites that they negative.

Additional standard infection control measures were also implemented, including screening, decolonization of patients and staff, reinforcement of hand hygiene practices, environmental cleaning and decontamination, and closing the ward to new admissions. Since the patient and staff decolonization was combined with environmental decontamination, the investigators were unable to determine the degree to which each procedure contributed to the outcome.

They showed that even in a busy hospital environment, where they’ve got bed occupancy rates of 100% and above, they were able to go in and decontaminate all the clinical areas in the ward over a period of two days, and that process had a sustained environmental impact.

An infection disease specialist at the Royal Hampshire Country Hospital in Winchester, where the outbreak occurred, said this episode was his hospital’s first experience using the hydrogen peroxide vapor contamination system, they suspect that there’s a lot more environmental contamination than they realize in many clinical areas. If they had the facilities to do this regularly, it would be a major step in reducing transmission of hospital-acquired infection.

In tests, hydrogen peroxide vapor has also been used to deactivate Mycobacterium tuberculosis in a containment cabinet and in a room (J Clin Microbial, 2007; 45:810-815) as well as to deactivate bacterial endoscopies, vegetative bacteria, and viruses.