biofilms had sheared off and settled elsewhere in the rig, therefore, providing less favourable conditions for to grow in these sections. Legionella Because water was circulated through the rigs continuously at a relatively high rate, and because 3 litres of water were drawn off and 3 litres of fresh water were added to the rigs daily, dispersion of biofilms most likely occurred frequently, which is supported by the variability in the TVC and results. Legionella Less were found in the samples taken from the copper rig A than in the Legionella polyethylene rig A after rigs A were used to inoculate rigs B and C. This could be explained by the removal of sections and water from rigs A for rigs B and C and by doing so a substantial amount of the established biofilms that had formed beforehand in the copper rig A was removed from the rig. The conditions within the copper rig A may have, therefore, become less favourable for to grow. Legionella Although a superior biocidal action of copper compared to polyethylene was not demonstrated in the initial experiment with rigs A, less were found in the Legionella copper rigs B and C than in the polyethylene rigs B and C. The counts Legionella found in polyethylene rigs B and C were ~473% higher than those found in copper rigs B and C. Interestingly, the found in all rigs during this study, Legionella L. pneumophila serogroup 2-14, were different from the species introduced to the rigs, L. pneumophila serogroup 1 and non-pneumophila. This suggested that the local Legionella environment in both rigs promoted the growth of serogroup 2-14, and L. pneumophila that the inoculum introduced could have contained a mixture, including serotypes not readily detectable in the inoculum at the initial stages. Page 203 of 229
biofilms had sheared off and settled elsewhere in the rig, therefore, providing less favourable conditions for Legionella to grow in these sections. Because water was circulated through the rigs continuously at a relatively high rate, and because 3 litres of water were drawn off and 3 litres of fresh water were added to the rigs daily, dispersion of biofilms most likely occurred frequently, which is supported by the variability in the TVC and Legionella results. Less Legionella were found in the samples taken from the copper rig A than in the polyethylene rig A after rigs A were used to inoculate rigs B and C. This could be explained by the removal of sections and water from rigs A for rigs B and C and by doing so a substantial amount of the established biofilms that had formed beforehand in the copper rig A was removed from the rig. The conditions within the copper rig A may have, therefore, become less favourable for Legionella to grow. Although a superior biocidal action of copper compared to polyethylene was not demonstrated in the initial experiment with rigs A, less Legionella were found in the copper rigs B and C than in the polyethylene rigs B and C. The Legionella counts found in polyethylene rigs B and C were ~473% higher than those found in copper rigs B and C. Interestingly, the Legionella found in all rigs during this study, L. pneumophila serogroup 2-14, were different from the species introduced to the rigs, L. pneumophila serogroup 1 and Legionella non-pneumophila. This suggested that the local environment in both rigs promoted the growth of L. pneumophila serogroup 2-14, and that the inoculum introduced could have contained a mixture, including serotypes not readily detectable in the inoculum at the initial stages. Page 203 of 229
Birgitta-Bedford-Thesis-2012.docx