Legionella testing laboratories will usually express their findings across all Legionella species using available culture methodologies (through ISO or CDC). In some cases, laboratories are required by regulations to do so. While on the surface, testing for all species of Legionella would seem to be more protective of public health, evolving information has shown the opposite. This bears out in the literature to be the statistically and internationally accepted logic. In September 2017 the World Health Organization released its recommendation that water systems be monitored for Legionella pneumophila specifically. Their report was confirmation that Pneumophila is clearly recognized as the causative agent of legionellosis, and not the other Legionella species. Identification of non-pneumophila species could lead directly to unnecessary response and expense. The door could be opening for the acceptance of more focused testing methods, where specific isolation of Pneumophila promotes better problem ID, testing accuracy, and mostly reduces the cost of administering a water management plan.
Written by: John D. Caloritis, CWT, Technology Director