Abstract
Positive pressure suits are widely used at BSL-4 to protect operators from contact with microbiological agents. As there is the potential for the outside of the suits to become contaminated during use, they must be decontaminated prior to final exit from the high-containment laboratory. Chemical showers are used to remove biological material from suits, and the shower effluent is collected for subsequent treatment by heat or chemicals. The efficacy of showering to clean/remove biological materials from two different BSL-4 suits (ILC Dover and Delta) was studied using Bacillus atrophaeus spores dried directly onto the suit surface as a surrogate contaminant, with a 4 log colony forming unit (cfu) reduction pass criterion required. Initial studies using water alone, without disinfectant, achieved a 1–2 log cfu reduction in the microbial contamination. However, direct scrubbing, using a lightweight brush combined with relatively short cycle times (6 minutes) and low water volumes (<45 L per cycle) achieved an average spore reduction of 3.4 log cfu from the suit. The log cfu reduction was dependent on suit type, position of the contamination on the suit surface, and suit fit. Higher reductions (mean 4.2 log cfu) were achieved with the ILC Dover suit than the Delta suit (mean 3.6 log cfu) when the tests were undertaken using experienced staff who had been matched to the suit size. The study highlights that assumptions cannot be made about the efficacy of shower decontamination systems for BSL-4 facilities and that familiarization with decontamination improves the efficacy of removal of biological material during showering.