Publication: Predictive factors of Legionella pneumophila contamination in cooling tower water
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Issued Date
2014-01-13
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11786221
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2-s2.0-84892616808
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Mahidol University
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SCOPUS
Bibliographic Citation
Air, Soil and Water Research. Vol.7, (2014), 11-17
Suggested Citation
Pipat Lluksamijarulkul, Sumawadee Kornkrerkkiat, Cchayaporn Saranpuetti, Ddusit Sujirarat Predictive factors of Legionella pneumophila contamination in cooling tower water. Air, Soil and Water Research. Vol.7, (2014), 11-17. doi:10.4137/ASWRr.S12972 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/33913
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Title
Predictive factors of Legionella pneumophila contamination in cooling tower water
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Abstract
A cross-sectional study of 160 water samples collected from 72 cooling towers in 4 hospitals, 7 department stores, and 3 hotels in Bangkok was carried out to investigate Legionella pneumophila contamination and its predictive factors. All water samples were cultured for Legionella spp. and tested for L. pneumophila by real-time polymerase chain reaction (PCR). Some cooling tower parameters were measured and recorded. Data were analyzed using χ2-test, odds ratio and stepwise logistic regression analysis at the significant level of α = 0.05. Results revealed that the Legionella spp. contamination was 20.0% (32/160) and for L. pneumophila was 61.3% (98/160). The sensitivity of real-time PCR was higher than that of the culture. Factors significantly asso-ciated with L. pneumophila contamination by χ2-test were: the cooling tower model, size, use duration, pH, water temperature, use of ozone, and residual free chlorine (95% CI of OR > 1.0, P < 0.05). After stepwise logistic regression analysis, four predictive factors remained. These included the cooling tower model being a cross-flow type (adjusted OR = 3.1, 95% CI = 1.2-7.8, P = 0.017), use duration > 5 years (adjusted OR = 3.6, 95% CI = 1.3-10.1, P = 0.016), water temperature < 29.4°C (adjusted OR = 7.9, 95% CI = 2.1-29.6, P = 0.002), and residual free chlorine < 0.2 ppm (adjusted OR = 8.5, 95% CI = 2.1-34.9, P = 0.003). Additionally, the risk probability for L. pneumophila contamination was estimated to be 13.9-97.1%, depending on the combination of predictive factors. © the authors, publisher and licensee Llibertas Academica Llimited.