Reducing the spread of Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus on a burns unit through the intervention of an infection control bundle

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii are major nosocomial pathogens in burns units. We investigated the impact of an infection control bundle on the incidence of nosocomial MRSA and A. baumannii in our burns unit, comparing a pre-intervention period (December 2006–August 2008) with an intervention period (September 2008–December 2009). The bundle comprised regular hydrogen peroxide vapour (HPV) disinfection of the rooms following discharge of patients colonized or infected by multidrug-resistant bacteria, pre-emptive cohort isolation of newly admitted patients before being proven culture negative, cohorting of colonized or infected patients, installation of two air disinfection systems in the corridors of the unit and improvement of material storage. We also investigated the microbiological efficacy of HPV disinfection by sampling the environment before and after HPV treatments. HPV disinfection eliminated pathogens from the environment and significantly reduced total bacterial surface counts, and total fungal air and surface counts, on both a unit and room scale. The incidence of nosocomial MRSA infection or colonization fell by 89.3% from 7.22 to 0.77 cases/1000 patient days (p < 0.0001) and A. baumannii fell by 88.8% from 6.92 to 0.77 cases/1000 patient days (p = 0.002) in the intervention period with no further outbreaks of these organisms occurring in this period. The infection control bundle resulted in a significant reduction in the incidence of nosocomial MRSA and A. baumannii in our burns unit and prevented further outbreaks of these organisms.

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii are serious nosocomial pathogens due to a combination of their environmental resilience, their association with antimicrobial resistance and their outbreak potential [1], [2], [3], [4], [5]. Surface contamination has been implicated in the transmission of these two organisms [6] and previous room occupancy by patients with MRSA or A. baumannii infection or colonization is an independent risk factor for the acquisition of these pathogens by patients subsequently admitted to the same rooms [7], [8].

MRSA and A. baumannii are particularly significant in burns patients who are uniquely susceptible to infection and colonization with these organisms [9], [10], [11], [12], [13], [14]. Affected burns patients represent a reservoir for spread of these pathogens to the rest of the hospital [15]. MRSA and A. baumannii outbreaks in burns units are common [4], [11], [13], [16] and can continue for many years [14], [15], [16], [17], [18], [19], [20].

Infection control interventions such as patient screening, cohort isolation, improved hand hygiene compliance, enhanced cleaning and environmental disinfection have been successful at reducing nosocomial infection rates and controlling outbreaks due to MRSA and A. baumannii in numerous reports [3], [4], [21], [22], [23]. MRSA and A. baumannii can be difficult to eradicate from contaminated surfaces using conventional cleaning and disinfection methods [1], [2], [21], [24]. Thus, we decided to implement a hydrogen peroxide vapour (HPV) system, which has been shown to eradicate these organisms from environmental surfaces and help to bring hospital outbreaks under control [1], [21], [24], [25], [26]. An outbreak of MRSA on our burns unit prompted us to implement an infection control bundle. Here we present our experience in the management of the MRSA outbreak, and the impact of the bundle on another key pathogen, A. baumannii. We also evaluated the microbiological impact of HPV in this setting.