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.

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Journal of Hospital Infection
Department of Medical Microbiology and Infectious Diseases

Sarink, M.J., Pirzadian, J., van Cappellen, G., Tielens, L., Verbon, A., Severin, J., & van Hellemond, 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