A RANDOMISED PROSPECTIVE COMPARISON OF TWO TYPES OF OCCLUSIVE CLOTHING USING BACTERIAL AIR COUNTS

Abstract

Background: Ultraclean air (UCA) in the operating theatre has been defined as less than 10 colony forming units (CFU)/m3. Wearing a Body Exhaust Suit (BES) in clear air has been shown to reduce infection from 1.0% to 0.1%. A trial in our unit in 2003 found bacterial air counts of 1 CFU/m3 with Rotecno gowns made from polyester T85392 compared to 0.5 CFU/m3 with BES. The same Rotecno gowns have since been used for arthroplasty surgery in our unit as this difference was not felt to be clinically significant. A new type of gown, manufactured by Gore ltd. was offered to our hospital. These gowns consist of a three layer laminate containing polyester and polytetrafluoroethylene (PTFE) and were advertised as impervious to liquids, bacteria and viruses. Their laboratory results were deemed to be superior to Rotecno gowns on standard testing.

Aim: The aim of this study was to compare bacterial air counts using the existing Rotecno gowns with this new type of occlusive gown made by Gore ltd.

Methods: 56 joint replacements were allocated randomly to either the Rotecno or Gore gowns and also stratified to Total Knee Arthroplasty (TKR), Total Hip Arthroplasty (THA) or Revision THA. Bacterial air counts were measured for the first ten minutes of surgery using a Casella slit sampler which sampled air at 700 lt/min onto a nutrient agar plate. These plates were then incubated for 48 hours at 37 degrees Celcius and colonies were counted.

Results: The new gowns were associated with higher air counts (3.7 CFU/m) than the Rotecno gowns (1.2 CFU/m) (p=0.01). All Rotecno air samples were < 10 CFU/m3 but three of the Gore samples exceeded the clean air standard. The bacterial counts with the Rotecno gowns were the same as those in the 2003 study. TKA was associated with higher air counts than THA or Revision THA (p=0.04).

Conclusions: The new gowns may have been superior on the standard tests but they were not superior at preventing airborne bacterial dispersal. Rotecno gowns made from polyester T85392, although many years old, were still associated with very low air counts. This study highlights the importance of testing new materials in a clinical environment with UCA; in vitro testing alone is not an adequate assessment. This is especially important for TKA which was associated with higher counts.