Abstract
Deep infection occurs in 2–4% of lower limb arthroplasty resulting in increasing cost, co-morbidity and challenging revision arthroplasty surgery. Identifying the potential sources of infection helps reduce infection rates. The aim of our study is to identify the impact and potential for contamination of our hands and gowns whilst scrubbing using SSHS.
A colony-forming unit (CFU) is a pathogenic particle of 0.5 micrometers to 5 micrometers. Concurrent particle counts and blood agar exposure settle plates for 3 subjects and 1 alcohol cleaned mannequin; testing a standard arthroplasty hood, a SSHS with and without the fan on for a 2 minute exposure to represent scrubbing time. Microbiological plates were incubated using a standard protocol by our local microbiology department.
All SSHS were positive for gram-positive cocci with a mean colony count of 410cfu/m2. Comparing background counts for laminar flow (mean 0.7 particle/m3; 95% CI 0–1.4) versus scrub areas (mean 131.5 particle/m3; 95% CI 123.5–137.9; p=0.0003), however neither grew any CFU's with a 2-minute exposure. For the mannequin, the only significant result was with the fan on with a 1.5× increase in the particle count (p=0.042) and a correlating positive organism (13CFU/m2). With human subjects, however, the particle count increased by 3.75× the background count with the fan on (total p=0.004, CFU p=0.047) and all had positive cultures, mean 36 CFU/m2. There were no positive cultures with the standard arthroplasty hood or the SSHS with no fan on. If repeated in laminar flow, there was only a statistically significant increase with the fan on (p=0.049), but with negative cultures following a 2-minute exposure.
Sterile gloves and gowns can be contaminated when scrubbing with the SSHS fan on. We recommend having the fan switched off when scrubbing until the hood and gown is in place, ideally in a laminar flow environment.
