Verona-Integron-encoded-Metallo-b-lactamase-positive Pseudomonas aeruginosa (VIM-PA) is a cause of hard-to-treat nosocomial infections, and can colonize hospital water networks alongside Acanthamoeba. We developed an in-vitro disinfection model to examine whether Acanthamoeba castellanii can harbour VIM-PA intracellularly, allowing VIM-PA to evade being killed by currently used hospital disinfectants. We observed that A. castellanii presence resulted in significantly increased survival of VIM-PA after exposure to chlorine for 30 s or for 2 min. This undesirable effect was not observed after disinfection by 70% alcohol or 24% acetic acid. Confocal microscopy confirmed the presence of VIM-PA within A. castellanii pseudocysts. Our data indicate that A. castellanii contributes to persistent VIM-PA colonization of water systems after chlorine treatment.

Acanthamoeba, Pseudomonas aeruginosa, Disinfection, Chlorine, Infection control, Water supply,
Journal of Hospital Infection
Department of Medical Microbiology and Infectious Diseases

Sarink, M.J., Pirzadian, J., van Cappellen, W.A, Tielens, A.G.M, Verbon, A, Severin, J.A, & van Hellemond, J.J. (2020). Acanthamoeba castellanii interferes with adequate chlorine disinfection of multidrug-resistant Pseudomonas aeruginosa. Journal of Hospital Infection, 106(3), 490–494. doi:10.1016/j.jhin.2020.09.019