Sampling and inactivation of wet disseminated spores from flooring materials, using commercially available robotic vacuum cleaners

Aims: Four commercially available robotic vacuum cleaners were assessed for sampling efficiency of wet disseminated Bacillus atrophaeus spores on carpet, polyvinyl chloride (PVC) and laminate flooring. Furthermore, their operability was evaluated and decontamination efficiency of one robot was assessed, using a sodium hypochlorite solution. Methods and Results: In an environmental chamber, robots self-navigated around 4 m² of flooring containing a single contaminated 0·25 m² tile (c. 10⁴ spores per cm²). Contamination levels at predetermined locations were assessed by macrofoam swabs (PVC and laminate) or water soluble tape (carpet), before and after sampling. Robots were dismantled postsampling and spore recoveries assessed. Aerosol contamination was also measured during sampling. Robot sampling efficiencies were variable, however, robots recovered most spores from laminate (up to 17·1%), then PVC and lastly the carpet. All robots spread contamination from the ‘hotspot’ (all robots spread <0·6% of the contamination to other areas) and became surface contaminated. Spores were detected at low levels during air sampling (<5·6 spores per litre). Liquid decontamination inactivated 99·1% of spores from PVC. Conclusions: Robotic vacuum cleaners show promise for both sampling and initial decontamination of indoor flooring. Significance and Impact of the Study: In the event of a bioterror incident, e.g. deliberate release of Bacillus anthracis spores, areas require sampling to determine the magnitude and extent of contamination, and to establish decontamination efficacy. In this study, we investigate robotic sampling methods against high concentrations of bacterial spores applied by wet deposition to different floorings, contamination spread to other areas, potential transfer of spores to the operators and assessment of a wet vacuum robot for spore inactivation. The robots’ usability was evaluated and how they can be employed in real life scenarios. This will help to reduce the economic cost of sampling and the risk to sampling/decontamination teams.