Microbial contamination of powered air purifying respirators (PAPR) used during the COVID-19 pandemic: an in situ microbiological study

ABSTRACT OBJECTIVE To determine whether internal components of powered air purifying respirators (PAPR) used during the Corona virus 2019 disease (COVID-19) pandemic are contaminated with bacteria, fungi and/or any viral material. DESIGN & SETTING In situ microbiological study. Single NHS Trust, UK. OUTCOME MEASURES Growth of any bacteria or fungi, or positive polymerase chain reaction results for common respiratory viruses and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RESULTS 25 PAPR hoods were swabbed; ten (40%) returned positive results. Bacterial growth was detected on six hoods (bacillus simplex, kocuria rhizophilia, bacillus weihenstephensis, microcccus luteus and staphylococcus epidermidis); five of the hoods were positive for fungal growth (non-sporulating environmental mould, NSEM); all sampled hoods tested negative for both SARS-CoV-2 and an expanded panel of respiratory viruses. There was wide variation in the storage of cleaned hoods. CONCLUSION Despite following recommended cleaning procedures, bacteria and fungi can remain on the internal components of PAPR hoods, at levels significant enough to be swabbed and cultured. PAPR hoods have the potential to cross-infect wearers and patients and are used primarily by clinicians who fail to fit disposable FFP3 respirators; the female sex and non-Caucasian people are less likely to fit FFP3 respirators. The hoods tested cannot be adequately cleaned for use in high risk healthcare environments, PAPR hoods and tubes can act as fomites, and there are evident shortcomings in their provision. SUMMARY WHAT IS ALREADY KNOWN ON THIS TOPIC Prior to this study there had been no similar investigations looking at the microbiological contamination of PAPR hoods in situ in the real work place hospital environment. SARS-CoV-2 is able to persist in an infective state on surfaces for up to 72 hours. The possibility of internal contamination of PAPR had never been addressed by manufacturers as the hoods were not designed for shared usage. WHAT THIS PAPER ADDS PAPR hoods in their current form risk transmitting infection between users, and do not protect patients from infected healthcare workers It is possible to detect biological agents within the PAPR hoods despite cleaning as per guidelines An infected asymptomatic carrier is at risk of infecting those around them due to contaminated exhalation