Pathogen Control Engineering Institute

SCHOOL OF CIVIL ENGINEERING

 

Aerobiology Links

Main Aerobiology pages.


The Case Studies

Current Projects: We have several projects at the moment.

CFD Analysis of a TB ward: Redesigning ventilation in a TB ward in Peru.

Upper Room UV: Upper room ultra-violet light gives good coverage - how good is the protection?

Ionisers: There is a lot of myth surrounding ionisers - but they can be effective for infection control.

Hospital Monitoring: We regularly go into hospitals to monitor environmental contamination. What can be measured and what use can be made of findings?

Past Projects: Here you can see some of the completed projects.

Potential Use of Negative Air Ionisers as an Infection Control Measure in Intensive Care Units

The problem of healthcare associated infection continues to be a major cause of concern for healthcare providers and the public alike. Despite numerous strategies to tackle the issue, the incidence of HAI has remained unchanged for the past 20 years with up to 1 in 10 patients contracting an infection during a hospital stay. These statistics have prompted researchers to examine new ways to combat infection, including the use of engineering control devices within the environment. Negative air ionisers are known to have a cleaning effect on the air by increasing particle deposition through electrostatics. There have also been a number of studies that suggest they may have a biocidal effect both on airborne and surface-borne microorganisms.

Objectives

The aim of this study was to carry out a trail in a clinical environment to establish

  • the impact of negative air ionisers on the presence of Staphylococcus aureus and Acinetobactor spp. In the environment
  • the impact of negative air ionisers on the rate of infections/ patient colonizations with the same bacteria.

Methodologies

The study was carried out in the Intensive Care Unit at St James's University Teaching Hospital, Leeds . During the first 6 months of the study there were no ionisers in the unit. Twice weekly, microbial samples were taken on selected surfaces using swabs and from the air using a CM90 Cyclone air sampler ( Burkard , UK ) at two locations on the unit, to quantify the environmental levels of Staphylococcus aureus and Acinetobactor spp. In addition swabs were taken from patients on the ward to establish the rate of infection and/or colonization. In the second 6 months of the study, 6 negative air ionisers (Air Ion Technologies, UK ) were installed on the ward and operated continuously. The sampling for environmental and clinical isolates continued in the same way throughout this second period.

Key Results

The results showed no difference in the clinical or environmental isolates of S. Aureas over the period of the study, suggesting that ionisers are not effective against this species in this type of environment.

However, there was a statistically significant difference in the Acinetobacter isolates with and without the ionisers in operation. There was a noticeable increase in the environmental isolates, particularly in the air. More importantly, following the introduction of the ionisers there was a major reduction in Acinetobacter infections/colonizations, with the rate dropping to almost zero within the unit.

Following the success of this trial, the ionisers have remained in operation on the ICU and Acinetobactor infection rates have remained at significantly lower levels since. A further study, funded by the Engineering and Physical Sciences Research Council (EPSRC) is currently underway to understand more about the physical and biocidal effects of negative ions.

Further Reading

This project was undertaken with funding provided by NHS Estates. Further details of the outcomes can be found in the following publications:

Kerr KG, Beggs CB, Dean SG, Thornton J, Donnelly JK, Todd NJ, Sleigh PA, Qureshi A, Taylor CC [2006], Air ionization and colonization/infection with methicillin resistant Staphylococcus aureus and Acinetobacter species in an intensive care unit, Intensive care medicine , 32(2): 315-317