Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2017

Transmission of pathogens from dry surface biofilms: effect of glove type. (#165)

Karen Vickery 1 2 , Durdana Chowdhury 2 , Shamaila Tahir 2 , Mark Legge 2 , Honghua Hu 2 , Gregory Whiteley 3 , Anand Deva 2
  1. ASAM, Macquarie University, Ryde, NSW, Australia
  2. Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
  3. Whiteley Corporation, Nth Sydney, New South Wales, Australia

Introduction:

Pathogens can survive on dry hospital environmental surfaces for extended periods especially when incorporated into dry surface biofilms. Bacteria in biofilms are protected from desiccation and have increased tolerance to removal by cleaning agents and disinfectants. We have shown that bare hands can transmit biofilm bacteria from surface to surface and hence could play a significant role in healthcare associated infections (HAI).

Objectives:

To determine the effect of glove composition on the transfer rate of Staphylococcus aureus from biofilm.

Methods:

S. aureus biofilm was grown in vitro on polycarbonate coupons in the CDC bioreactor, using our validated methods of with periodic nutrition interspersed with long periods of dehydration, over a period of 12 days. Each coupon had approximately 107 bacterial cells. Transmission was tested by touching coupons, with either nitrile (n=18), latex (n=18) or surgical (n=18) gloved hands, and then pressing the finger and thumb onto the sterile horse blood agar (HBA) surface up to 19 consecutive times. The number of colony forming units (CFU) were recorded for each touch after incubating HBA plates at 37OC for 48 hours. The experiment was repeated following coupon treatment with 5% neutral detergent for 5 seconds.

Results:

Bacterial cells were readily transmitted via all three types of gloves, commonly used by healthcare workers (HCWs).  Although less than 1% of the biofilm was transferred, S. aureus was transferred to 19 surfaces, in sufficient numbers to cause infection from touching the biofilm once. Six times more bacteria were transferred by nitrile and surgical gloves when compared to latex gloves (P<0.001). Wetting the biofilm with 5% neutral detergent increased the transmission rate of bacteria by seven-fold (P<0.01).

Conclusion: Despite bacteria being incorporated into environmental biofilm and covered by exopolymeric substances (EPS or slime), bacteria are readily transferred by HCW’s gloved hands and this confirms the possibility that biofilm contributes towards patient colonization with pathogens and development of HAI.