Drug-Resistant A Baumannii Prevalent in Surroundings of Infected Patients
By Emma Hitt, PhD
Medscape Medical News
March 23, 2010 (Atlanta, Georgia) — The environment surrounding patients infected with multidrug-resistant Acinetobacter baumannii (MDR-AB) is contaminated about half of the time, new study findings suggest.
"Surfaces touched by healthcare workers during routine patient care, including supply carts, infusion pumps, and ventilator touch pads, are commonly contaminated," said Kerri A. Thom, MD, MS, assistant professor of epidemiology and preventive medicine at the University of Maryland in Baltimore, during her presentation.
She presented the findings here at the Fifth Decennial International Conference on Healthcare-Associated Infections 2010.
According to Dr. Thom and colleagues, the role of the environment in the transmission of MDR-AB is "incompletely understood." The researchers conducted a prospective cohort study of patients known to be colonized or infected with MDR-AB in the intensive care unit of a single institution from October 8, 2008 to January 28, 2009.
A total of 478 samples from 50 rooms were collected by swabbing 10 surfaces in each room. Samples were cultured and assessed with pulsed-field gel electrophoresis.
Of the samples, 9.8% were positive for A?baumannii. About half of the rooms were positive for MDR-AB at 1 or more sites tested. In each of the 50 rooms, the surfaces most likely to be contaminated were supply carts (20%), floors (16%), infusion pumps (14%), ventilator touch pads (11.4%), and bed rails (10.2%).
The researchers also analyzed the findings according to the time the positive culture was collected, comparing cultures collected within the previous 2 months (recent history) with those collected more than 2 months previous (remote history). They found that patients with a recent history of MDR-AB (78%) were no more likely to contaminate their environment than those with a remote history.
Among the 24 patients with an environmental culture positive for A?baumannii, 20 had a recent history of MDR-AB. In 17 of those cases, the patient and environmental isolates were genetically similar.
"A?baumannii is an important hospital pathogen," Dr. Thom told Medscape Infectious Diseases. "This organism is unique among Gram-negative pathogens, in that it has been shown to persist in the environment for prolonged periods of time," she said.
According to Dr. Thom, the surfaces most often touched by healthcare workers (supply carts, infusion pumps, and ventilators) are the most commonly contaminated, suggesting "a potential for transmission from one patient to another via the hands of healthcare workers," she said.
"These results provide more evidence of the need to achieve 100% compliance with hand hygiene, and suggest that more emphasis should be placed on routine cleaning and disinfection of environmental surfaces," she added.
L. Silvia Munoz-Price, MD, from the Division of Infectious Diseases at the University of Miami Miller School of Medicine in Florida, noted that these findings confirm that environmental surfaces in the proximity of patients infected with A?baumannii do, in fact, become contaminated with this organism.
According to Dr. Munoz-Price, the results of this study should be used to inform environmental personnel and healthcare workers about the importance of thoroughly cleaning and complying with hand hygiene, respectively.
"Environmental surfaces close to patients infected or colonized with A?baumannii should be cleaned extensively on a daily basis in order to decrease the possibility of horizontal transmission," she asserted.
The study received grant support from the National Institutes of Health. Dr. Thom and Dr. Munoz-Price have disclosed no relevant financial relationships.
Fifth Decennial International Conference on Healthcare-Associated Infections (ICHAI) 2010: Abstract?673. Presented March?20, 2010.
