Publication: Predictive factors of legionella pneumophila contamination in cooling tower water
Issued Date
2014-04-21
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Language
eng
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Mahidol University.
Bibliographic Citation
Soil and Water Research. Vol.7, 2014, 11-17
Suggested Citation
Pipat Luksamijarulkul, Sumawadee Kornkrerkkiat, Chayaporn Saranpuetti, Dusit Sujirarat, พิพัฒน์ ลักษมีจรัลกุล, ชญาภรณ์ ศรัณพฤติ, ดุสิต สุจิรารัตน์ Predictive factors of legionella pneumophila contamination in cooling tower water. Soil and Water Research. Vol.7, 2014, 11-17. doi:10.4137/ASWR.S12972 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/2185
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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 a = 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.
Sponsorship
This research project was supported by the Thailand Research Fund (TRF) and Square Cooling Tower Co., Ltd. for the TRF-Master Research Grants (Window I),
2011, and received a publication grant from the China Medical Board, Faculty of Public Health, Mahidol University.