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Impact of environmental factors on legionella populations in drinking water.

Schwake DO, Alum A, Abbaszadegan M - Pathogens (2015)

Bottom Line: Chlorination of the system had a greater effect on biofilm-associated Legionella concentrations, with populations returning to pre-chlorination levels within six weeks.Biofilms sampled from drinking water meters collected from two areas within central Arizona were analyzed via PCR for the presence of Legionella.Occurrence in only one area indicates that environmental differences in water distribution systems may have an impact on the survival of Legionella.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA. david.schwake@asu.edu.

ABSTRACT
To examine the impact of environmental factors on Legionella in drinking water distribution systems, the growth and survival of Legionella under various conditions was studied. When incubated in tap water at 4 °C, 25 °C, and 32 °C, L. pneumophila survival trends varied amongst the temperatures, with the stable populations maintained for months at 25 °C and 32 °C demonstrating that survival is possible at these temperatures for extended periods in oligotrophic conditions. After inoculating coupons of PVC, copper, brass, and cast iron, L. pneumophila colonized biofilms formed on each within days to a similar extent, with the exception of cast iron, which contained 1-log less Legionella after 90 days. L. pneumophila spiked in a model drinking water distribution system colonized the system within days. Chlorination of the system had a greater effect on biofilm-associated Legionella concentrations, with populations returning to pre-chlorination levels within six weeks. Biofilms sampled from drinking water meters collected from two areas within central Arizona were analyzed via PCR for the presence of Legionella. Occurrence in only one area indicates that environmental differences in water distribution systems may have an impact on the survival of Legionella. These results document the impact of different environmental conditions on the survival of Legionella in water.

No MeSH data available.


Related in: MedlinePlus

L. pneumophila concentration in 50 mL tap water incubated at 4 °C, 25 °C, and 32 °C over 97 days after inoculation with 3 × 107 cells. Day 0 represents sampling performed 2 h post inoculation. Error bars indicate standard error between two replicate cultures.
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pathogens-04-00269-f001: L. pneumophila concentration in 50 mL tap water incubated at 4 °C, 25 °C, and 32 °C over 97 days after inoculation with 3 × 107 cells. Day 0 represents sampling performed 2 h post inoculation. Error bars indicate standard error between two replicate cultures.

Mentions: During the first week of incubation, no significant decrease in the concentration of Legionella was observed at any temperature (Figure 1). At 4 °C, after the first week of a steady state, Legionella concentration decreased at an exponential rate for two months before stabilizing at 102 colony forming units (CFU)/mL for the remainder of the study period. At 25 °C, Legionella concentration decreased exponentially for 30 days and stabilized at approximately 105 CFU/mL. At 32 °C, Legionella concentration decreased at an exponential rate for 18 days and relatively stabilized at approximately 5 × 103 CFU/mL. After the initial decrease, the variation in concentration was more pronounced at 32 °C than for the other temperatures. After 11 months, Legionella concentrations at 4 °C, 25 °C, and 32 °C were <1 CFU/mL, <1 CFU/mL, and >103 CFU/mL, respectively, suggesting that long-term survival of Legionella was supported by the higher temperature.


Impact of environmental factors on legionella populations in drinking water.

Schwake DO, Alum A, Abbaszadegan M - Pathogens (2015)

L. pneumophila concentration in 50 mL tap water incubated at 4 °C, 25 °C, and 32 °C over 97 days after inoculation with 3 × 107 cells. Day 0 represents sampling performed 2 h post inoculation. Error bars indicate standard error between two replicate cultures.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493474&req=5

pathogens-04-00269-f001: L. pneumophila concentration in 50 mL tap water incubated at 4 °C, 25 °C, and 32 °C over 97 days after inoculation with 3 × 107 cells. Day 0 represents sampling performed 2 h post inoculation. Error bars indicate standard error between two replicate cultures.
Mentions: During the first week of incubation, no significant decrease in the concentration of Legionella was observed at any temperature (Figure 1). At 4 °C, after the first week of a steady state, Legionella concentration decreased at an exponential rate for two months before stabilizing at 102 colony forming units (CFU)/mL for the remainder of the study period. At 25 °C, Legionella concentration decreased exponentially for 30 days and stabilized at approximately 105 CFU/mL. At 32 °C, Legionella concentration decreased at an exponential rate for 18 days and relatively stabilized at approximately 5 × 103 CFU/mL. After the initial decrease, the variation in concentration was more pronounced at 32 °C than for the other temperatures. After 11 months, Legionella concentrations at 4 °C, 25 °C, and 32 °C were <1 CFU/mL, <1 CFU/mL, and >103 CFU/mL, respectively, suggesting that long-term survival of Legionella was supported by the higher temperature.

Bottom Line: Chlorination of the system had a greater effect on biofilm-associated Legionella concentrations, with populations returning to pre-chlorination levels within six weeks.Biofilms sampled from drinking water meters collected from two areas within central Arizona were analyzed via PCR for the presence of Legionella.Occurrence in only one area indicates that environmental differences in water distribution systems may have an impact on the survival of Legionella.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA. david.schwake@asu.edu.

ABSTRACT
To examine the impact of environmental factors on Legionella in drinking water distribution systems, the growth and survival of Legionella under various conditions was studied. When incubated in tap water at 4 °C, 25 °C, and 32 °C, L. pneumophila survival trends varied amongst the temperatures, with the stable populations maintained for months at 25 °C and 32 °C demonstrating that survival is possible at these temperatures for extended periods in oligotrophic conditions. After inoculating coupons of PVC, copper, brass, and cast iron, L. pneumophila colonized biofilms formed on each within days to a similar extent, with the exception of cast iron, which contained 1-log less Legionella after 90 days. L. pneumophila spiked in a model drinking water distribution system colonized the system within days. Chlorination of the system had a greater effect on biofilm-associated Legionella concentrations, with populations returning to pre-chlorination levels within six weeks. Biofilms sampled from drinking water meters collected from two areas within central Arizona were analyzed via PCR for the presence of Legionella. Occurrence in only one area indicates that environmental differences in water distribution systems may have an impact on the survival of Legionella. These results document the impact of different environmental conditions on the survival of Legionella in water.

No MeSH data available.


Related in: MedlinePlus