Q-280. Determining the Ability of Surface Wipes to Remove, Kill and Prevent the Transfer of Staphylococcus aureus from Contaminated Surfaces

G. J. Williams1, S. P. Denyer1, I. K. Hosein2, D. W. Hill2, J-Y. Maillard1;
1Cardiff Univ., Cardiff, UNITED KINGDOM, 2Univ. Hosp. of Wales, Cardiff, UNITED KINGDOM.

Background: Disinfection regimens adopted in ICUs in the UK include the use of disinfectant wipes. They are used to disinfect surfaces which are commonly contaminated with bacterial pathogens. We used our 3-step protocol to test the ability of wipes to remove, kill and prevent the transfer of bacteria from contaminated to clean surfaces. Methods: Meticillin-resistant or -susceptible Staphylococcus aureus (6 log10CFU) were inoculated onto steel discs with or without organic load and dried. Commercially available wipes containing either disinfectant (DIS), detergent (DET) or natural antimicrobial (NA) were used. Step 1: bacterial removal was assessed by mechanically rotating wipes against surfaces for 10s at 60 rpm, exerting a weight of 100 ± 5 g. These parameters were based on in situ usage of wipes in ICUs. Discs were transferred to a neutralizing solution and remaining bacteria were re-suspended and counted. Step 2: bacterial transfer from wipes was assessed by eight mechanical adpression transfers to agar/neutralizer plates. Step 3: antimicrobial activity was measured by direct inoculation of the wipes followed by neutralization after 10s contact and enumeration. Results: In comparative studies of dirty and clean surfaces, respectively, DET produced a 1.73 ± 0.21 and 1.73 ± 0.25 log10 bacterial removal, DIS achieved a 1.9 ± 0.55 and 2.57 ± 0.51 log10 bacterial removal and NA wipes produced a 3.63 ± 0.43 and 4.54 ± 0.63 log10 bacterial removal. DET and NA wipes transferred each strain in numbers too numerous to count onto consecutive agar/neutralizer plates. Cell numbers transferred by DIS were mostly countable and decreased through the adpression series. DET had no antimicrobial activity, NA wipes produced <1 log10 reduction and DIS achieved a 2.68 ± 0.33 and 3.55 ± 0.64 log10 reduction in the presence and absence of organic load, respectively. Conclusion: The use of the 3-step protocol allowed a risk assessment to be made for using wipes in ICUs. Wipes can potentially result in cross-contamination of surfaces when initially high microbial contamination levels are present. We recommend that a wipe is not to be used on consecutive surfaces, but only on a small area and discarded immediately after use.