Transfer of dry surface biofilm in the healthcare environment: the role of healthcare workers' hands as vehicles

D Chowdhury; S Tahir; M Legge; H Hu; T Prvan; K Johani; G S Whiteley; T O Glasbey; A K Deva; K Vickery

doi:10.1016/j.jhin.2018.06.021

Transfer of dry surface biofilm in the healthcare environment: the role of healthcare workers' hands as vehicles

J Hosp Infect. 2018 Nov;100(3):e85-e90. doi: 10.1016/j.jhin.2018.06.021. Epub 2018 Jun 28.

Authors

D Chowdhury¹, S Tahir¹, M Legge¹, H Hu¹, T Prvan², K Johani³, G S Whiteley⁴, T O Glasbey⁵, A K Deva¹, K Vickery⁶

Affiliations

¹ Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia.
² Department of Statistics, Macquarie University, New South Wales, Australia.
³ Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia; Central Military Laboratories and Blood Bank, Prince Sultan Military Medical City, Riyadh, Saudi Arabia.
⁴ Western Sydney University, School of Medicine, Campbelltown, Australia; Whiteley Corporation Pty Ltd, North Sydney, New South Wales, Australia.
⁵ Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia; Whiteley Corporation Pty Ltd, North Sydney, New South Wales, Australia.
⁶ Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia. Electronic address: Karen.vickery@mq.edu.au.

PMID: 29964099
DOI: 10.1016/j.jhin.2018.06.021

Abstract

Background: Dry surface biofilms (DSBs) persist for extended periods in hospital, and may play a significant role in transmission of healthcare-associated infections.

Aim: To determine whether DSBs may be transferred from hospital surfaces to healthcare workers' hands.

Method: Twelve-day Staphylococcus aureus DSB was grown on polycarbonate and glass coupons in a CDC Biofilm Reactor^®. A total of 1.8 × 10⁶ and 8.8 × 10⁵ bacteria grew on the polycarbonate and glass coupons respectively. Transmission was tested by lifting the coupon with forefinger and thumb of ungloved hands to a height of 30 cm, then touching horse blood agar (HBA) plates 19 sequential times. Transferred bacterial number was determined by colony-forming units. The effect of DSB wetting on biofilm transfer was tested with 5% neutral detergent treatment for 5 s.

Findings: Between 5.5 and 6.6% of the DSB bacteria were transferred to hands with one touch and ∼20% were then transferred to HBA with one touch, giving an overall transfer rate of 1.26% and 1.04% for polycarbonate and glass coupons, respectively. Detergent treatment had little effect on bacterial removal from coupons, but, for biofilm grown on polycarbonate, significantly increased transferral to HBA (P < 0.001) to 5.2%. Large numbers of bacteria were transferred by bare hands to multiple fomites. One-third of polycarbonate coupons transferred >1000 colonies during the first five sequential touches. Sufficient bacteria to cause infection were transmitted up to 19 times following one touch of the DSB.

Conclusion: DSB bacteria are transferred by hands from one fomite to multiple fomites, suggesting that DSB may serve as a persistent environmental source of pathogens.

Keywords: Cleaning; Dry surface biofilms; Healthcare-associated infections; Staphylococcus aureus; Transmission.

MeSH terms

Biofilms / growth & development*
Colony Count, Microbial
Environmental Microbiology*
Hand / microbiology*
Health Personnel*
Humans
Staphylococcus aureus / growth & development*
Staphylococcus aureus / isolation & purification*