Galleria mellonella as a Model to Study the Effect of Antimicrobial Surfaces on Contamination by Staphylococcus aureus

Author(s): Astrid Mayr, Dorothea Orth-Holler, Holger Heinrich, Guido Hinterberger, Isabella Wille, Verena Naschberger, Cornelia Lass-lorl, Ulrike Binder

Objective: The role of the inanimate environment in the transmission of healthcare-associated infections (HCAIs) is increasingly recognized. Hence, several self-disinfecting surfaces have gained attention as new infection control strategies. The objective of this study was to assess the antimicrobial efficacy of membrane-active polycation (maPK) surfaces against Staphylococcus aureus (S. aureus) applying the in vivo Galleria mellonella (G. mellonella) contamination model.

Methods: In the first set-up maPK surfaces were contaminated with S. aureus and G. mellonella larvae were placed on the surface for 45 min. In the second set-up larvae were contaminated with S. aureus and transferred to maPK surfaces. Finally, the cross-over rates to larvae and maPK-surface were determined. Additionally, log reduction values (LRVs) of S. aureus on contaminated maPK and larvae were calculated.

Results: The first experimental set-up revealed a significantly higher cross-over rate of S. aureus to the larvae from contaminated control surface (~2 x 10³ colony forming untis (cfu)/mL) when compared to maPK surface (~5.1 x 101 cfu/mL). In the second set-up the cross-over rate of S. aureus from larvae to the control surface was significantly higher (~5.1 x 10³ cfu/plate) than to the maPK surface (~2.1 x 10¹ cfu/plate). In both experiments LRVs were superior on maPK with 98.1% (p=0.0117) and 99.5% (p=0.0001) reduction, respectively.

Conclusions: This in vivo study reveals the ability of maPK surfaces to reduce bacterial contamination and highlights the potential power to avoid cross-contamination from environmental surface.