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.