When water samples are positive for Legionella, is it common or rare to find more than one species present? Does the presence of one species necessarily indicate others are present, but perhaps not detectable by the lab methods in use?
It is not unusual to find multiple Legionella species and serogroups in a water system. There is no data to indicate that the presence of one species correlates or predicts the presence of another species. Legionella anisa is a common colonizer of water distribution systems. However, we believe that this species is unlikely to be a pathogen.