VIM-Positive Pseudomonas aeruginosa High-Risk Clones and the Hospital Environment

Pseudomonas aeruginosa is one of the most common healthcare-associated pathogens worldwide, and infections are difficult to treat due to intrinsic resistance and emerging resistance to carbapenem antibiotics. P. aeruginosa is frequently recovered from wet niches in hospitals, such as sink drains, where it may form persistent reservoirs that are impossible to properly clean. In this thesis, carbapenem-resistant, high-risk clones of VIM-2-positive P. aeruginosa (VIM-PA) were investigated with a focus on their presence, persistence, and transmission in hospital environments. Firstly, a national surveillance pilot study to identify carbapenemase-producing P. aeruginosa in the Netherlands was described, showing that VIM-PA high-risk clone ST111 had spread unnoticed within many Dutch hospitals. Focus was then narrowed to the Erasmus MC: The microbial compositions of sink drain reservoirs were characterized using culturomics to find microorganisms that might resist colonization by VIM-PA; VIM-PA hiding intracellularly within Acanthamoeba castellanii was discussed as a method VIM-PA may employ to evade disinfection in water systems; sink design factors contributing to dispersal from drains were studied, and adjustments to minimize splashing (e.g. installing sink drain plugs, offsetting the faucet) were recommended; finally, whether Pseudomonas spp. carried blaVIM-2-encoding plasmids in our hospital, and the role of sink drain reservoirs in blaVIM-2 transmission, were explored. The strategies proposed in this thesis for minimizing transmission from sink drain reservoirs and managing VIM-PA colonization in the environment pave the way toward making safer patient spaces in hospitals.