Occurrence of Legionella in groundwater: an ecological study

The natural habitat of Legionella is the water environment. Little is known about their presence in groundwaters in spite of the fact that many millio ns around the globe regularly rely on groundwaters. This pilot study was ai med at evaluating the occurrence of Legionella in groundwater samples (wate r and biofilms) collected from various sites. Water and biofilm samples fro m selected groundwater sources were examined for Legionella using culture m edia (selective and non-selective) and a semi-nested PCR assay. Innovative approaches such as immunomagnetic separation (IMS) in combination with cult ivation and flow cytometry were also evaluated. The findings available thus far show that (a) Legionella could be readily recovered from groundwater s amples by cultivation even though their numbers showed considerable variati ons, (b) surprisingly, the PCR methodology was not yet as sensitive as cult ivation and (c) flow cytometry was not directly applicable on natural sampl es because of debris and the high number of heterotrophic associated microf lora from which some members were likely to cross-react with the monoclonal antibody used for separation procedures (IMS).