Showering BSL-4 Suits to Remove Biological Contamination

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. Materials and Methods This study measures the effectiveness of biological material removal not disinfection activity and so a resistant, non-pathogenic spore tracer was chosen. Ethics The initial study plan required the use of volunteers and hence the project was submitted to the UK NHS Na

Evaluation of Nine Positive Pressure Suits for Use in the Biosafety Level-4 Laboratory

“…2,3,9 As such, suits must withstand repeated exposure to the chemical disinfectant used at a particular facility. Analyses of mechanical resistance of suit materials following exposure to 5% Micro-Chem Plus™, the disinfectant used for many BSL-4 chemical showers in Canada and the United States, 10,11 proved that the majority of materials showed no decreased performance in resistance tests for puncture, abrasion and flex-cracking compared to untreated control swatches. Only butyl-coated fabrics appeared to suffer deleterious effects following 5% Micro-Chem Plus™ treatment, as evidenced by performance of materials from suits 2 and 8.…”

Peracetic acid‐based disinfectant is the most appropriate solution for a biological decontamination procedure of responders and healthcare workers in the field environment

“…While residual contamination in the case of chemical/radiological events can be immediately measured, methods instantly evaluating the presence of biological agents have not been developed. To our best knowledge, only a few studies related to biological decontamination of personnel in operationally relevant conditions have been conducted so far (Darby and Glass 2002;Parks et al 2013;Anon. 2013;Archer et al 2018).…”

“…To our best knowledge, only a few studies related to biological decontamination of personnel in operationally relevant conditions have been conducted so far (Darby and Glass 2002 ; Parks et al . 2013 ; Anon. 2013 ; Archer et al .…”

Efficacy Testing of Personal Protective Filters on Biosafety Level 4 Positive Pressure Suits

“…3 Cabinet laboratories can be ergonomically challenging for certain tasks and are not generally suitable for large animal work. 4 As a result, the majority of BSL-4 laboratories are suit laboratories, 5 where the workers enjoy enhanced range of motion and visibility compared with those working in cabinet laboratories.…”

“…Extensive training 6 and a range of complex equipment and facilities are used by those working at BSL-4 to pro-tect operators from exposure to infectious agents. 4 As a form of personal protective equipment, a positive pressure suit completely isolates the worker in a safe microenvironment from the potentially hazardous laboratory environment. 7 The suits offer protection in two ways: a hermetically sealed physical barrier created by the impermeable suit material and the positive pressure provided by the breathing air, which forces clean air outward from the suit through one way valves and keeps potentially contaminated laboratory air from being drawn into the suit even during a suit breach scenario.…”