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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 in flowing water of a model drinking water distribution system over a period of 131 days after inoculation with 107 cells. Note: Day 0 corresponds to sampling performed 2 h after inoculation. The gray square at day 131 corresponds to sampling performed 2 h after chlorination. Error bars indicate standard error of samples collected from two separate ports before and after flushing with 1 L of water.
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pathogens-04-00269-f004: L. pneumophila in flowing water of a model drinking water distribution system over a period of 131 days after inoculation with 107 cells. Note: Day 0 corresponds to sampling performed 2 h after inoculation. The gray square at day 131 corresponds to sampling performed 2 h after chlorination. Error bars indicate standard error of samples collected from two separate ports before and after flushing with 1 L of water.

Mentions: Within hours of inoculation, similar Legionella concentrations (approximately 1.5 × 103 CFU mL−1) were detected in samples collected from both sampling ports (Figure 4) of the MDS. During the first week, Legionella concentration rapidly fluctuated and then stabilized at approximately 8 × 102 CFU mL−1. From day 20 through day 45, a steady increase in concentration was observed, with a peak concentration of 3.5 × 103 CFU mL−1, followed by a steady decrease until day 60. After this point, Legionella concentration stabilized at approximately 1.6 × 103 CFU mL−1 until day 126. At day 131 a concentration of 4.3 × 103 CFU mL−1 was recorded, followed by 1.7 × 103 CFU mL−1 after chlorination. Three days after inoculation of the MDS, an initial biofilm concentration of 8.8 × 102 CFU cm−2 was measured (Figure 5). Concentration within biofilm samples increased steadily, with a peak at 2.2 × 104 CFU cm−2 on day 28, followed by a steady decrease until reaching a stable concentration near 4.4 × 103 CFU cm−2 on day 68 until day 131. After chlorination, biofilm concentrations (averaged from coupons and pipe loop segments) decreased to 1.1 × 102 CFU mL−1. After six weeks, concentrations in both biofilms and the MDS flowing water increased to pre-chlorination levels. In addition, culturable Legionella were detected for over a year in the MDS, with approximately 1.5 × 103 CFU mL−1 in flowing water and 2 × 103 CFU cm−2 in biofilm samples 13 months after the initial inoculation.


Impact of environmental factors on legionella populations in drinking water.

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

L. pneumophila in flowing water of a model drinking water distribution system over a period of 131 days after inoculation with 107 cells. Note: Day 0 corresponds to sampling performed 2 h after inoculation. The gray square at day 131 corresponds to sampling performed 2 h after chlorination. Error bars indicate standard error of samples collected from two separate ports before and after flushing with 1 L of water.
© Copyright Policy
Related In: Results  -  Collection

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

pathogens-04-00269-f004: L. pneumophila in flowing water of a model drinking water distribution system over a period of 131 days after inoculation with 107 cells. Note: Day 0 corresponds to sampling performed 2 h after inoculation. The gray square at day 131 corresponds to sampling performed 2 h after chlorination. Error bars indicate standard error of samples collected from two separate ports before and after flushing with 1 L of water.
Mentions: Within hours of inoculation, similar Legionella concentrations (approximately 1.5 × 103 CFU mL−1) were detected in samples collected from both sampling ports (Figure 4) of the MDS. During the first week, Legionella concentration rapidly fluctuated and then stabilized at approximately 8 × 102 CFU mL−1. From day 20 through day 45, a steady increase in concentration was observed, with a peak concentration of 3.5 × 103 CFU mL−1, followed by a steady decrease until day 60. After this point, Legionella concentration stabilized at approximately 1.6 × 103 CFU mL−1 until day 126. At day 131 a concentration of 4.3 × 103 CFU mL−1 was recorded, followed by 1.7 × 103 CFU mL−1 after chlorination. Three days after inoculation of the MDS, an initial biofilm concentration of 8.8 × 102 CFU cm−2 was measured (Figure 5). Concentration within biofilm samples increased steadily, with a peak at 2.2 × 104 CFU cm−2 on day 28, followed by a steady decrease until reaching a stable concentration near 4.4 × 103 CFU cm−2 on day 68 until day 131. After chlorination, biofilm concentrations (averaged from coupons and pipe loop segments) decreased to 1.1 × 102 CFU mL−1. After six weeks, concentrations in both biofilms and the MDS flowing water increased to pre-chlorination levels. In addition, culturable Legionella were detected for over a year in the MDS, with approximately 1.5 × 103 CFU mL−1 in flowing water and 2 × 103 CFU cm−2 in biofilm samples 13 months after the initial inoculation.

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