Sessile microbiological communities or biofilms can pose problems in building water systems. For example, it has been suggested that Legionella pneumophila, the organism responsible for Legionnaires'
disease, proliferates in the biofilm environment. We report here the effectiveness of oxidizing biocides for the control of Legionella in well-established biofilms grown from native bacterial isolates. These
studies were conducted in the laboratory using a 10-liter model water system. This work shows that control of Legionella is more difficult in the biofilm environment than in the planktonic environment. In general, biocides that are effective against biofilm bacteria are effective against biofilm-associated Legionella as well.
Keywords: Legionella pneumophila, Legionnaires' disease, biofilm, heterotrophic bacteria, HPC, HBC, biocide, stabilized bromine, stabilized bromine chloride, sodium bromide, activated sodium bromide, chlorine, bleach, BCDMH, minimum biofilm eradication concentration, MBEC, Calgary Biofilm Device, CBD, glutaraldehyde, isothiazolone, quaternary compound, polyquat.