- Legionella pneumophila (Lp) gains disinfection resistance by being harboured within free-living amoebae (FLA).
- Supplementing growth medium with 8 mM magnesium is sufficient to produce Lp grown in vitro with an infectivity equivalent to that of Lp grown via the protozoan-primed route.
- The Lp forms tested exhibited greater monochloramine resistance than Lp grown in standard media, indicating that passage through FLA not only increases Lp’s infectivity but also enhances its monochloramine resistance.
- Laboratory-based testing of disinfection strategies should employ conditions that simulate or replicate intracellular growth to accurately assess disinfectant resistance.