Predictive parameters of Legionella pneumophila occurrence in hospital water: HPCs and plumbing system installation age
- 195 Downloads
Occurrence of Legionella pneumophila can be relevant to the installation age and the presence of heterotrophic plate counts (HPCs). This research illustrates L. pneumophila contamination of hospital water in accordance with the installation age and the presence of HPCs. One hundred and fifty samples were collected from hot and cold water systems and cultured on R2A and BCYE agar. L. pneumophila identification was done via specific biochemical tests. HPCs and L. pneumophila were detected in 96 and 37.3 % of the samples, respectively. The mean of HPCs density was 947 ± 998 CFU/ml; therefore, 52 % of the samples had higher densities than 500 CFU/ml. High densities of HPCs (>500 CFU/ml) led to colonization of L. pneumophila (≥1000 CFU/ml), mainly observed in cooling systems, gynecological, sonography, and NICU wards. Chi2 test demonstrated that higher densities (>500 CFU/ml) of HPCs and L. pneumophila contamination in cold water were more frequent than warm water (OR: 2.3 and 1.49, respectively). Univariate regressions implied a significant difference between HPCs density and installation age in positive and negative tests of L. pneumophila (OR = 1.1, p < 0.001, OR = 1.2, p < 0.001). Mann-Whitney U test implied the significant effects of HPCs and installation age on L. pneumophila occurrences (p < 0.001). Spearman correlation and multivariate linear regression revealed significant differences between L. pneumophila and HPCs densities (r s = 0.33, p < 0.001 and ß = 0.11, p = 0.02), but nonsignificant difference with installation age (r s = 0.33, p < 0.001 and ß = 0.0, p = 0.91). The occurrence of L. pneumophila, HPCs, and installation age are relevant; so, plumbing system renovation with appropriate materials and promotion of the effective efforts for hospital’s water quality assurance is highly recommended.
KeywordsLegionella Heterotroph bacteria Water contamination Hospital water
The authors would like to acknowledge Health School and Health Research Center of Baqiyatallah University of Medical Sciences. The authors declare that they have no competing of interests. This paper originated from MS student thesis which was not funded. To take water specimens from hospitals, no specific permissions were required for sampling or activities in these locations.
- Allen, J. G., Myatt, T. A., Macintosh, D. L., Ludwig, J. F., Minegishi, T., Stewart, J. H., et al. (2012). Assessing risk of health care-acquired Legionnaires’ disease from environmental sampling: the limits of using a strict percent positivity approach. American Journal of Infection Control. doi: 10.1016/j.ajic.2012.01.013.Google Scholar
- American Public Health Association (1998). Standard methods for the examination of water and wastewater (p. 1268). Washington, DC: American Public Health Association.Google Scholar
- Arvand, M., Jungkind, K., & Hack, A. (2011). Contamination of the cold water distribution system of health care facilities by Legionella pneumophila: do we know the true dimension? Eurosurveillance, 16, 1–6.Google Scholar
- Braks, M. A., & de Roda Husman, A. M. (2013). Dimensions of effects of climate change on water-transmitted infectious diseases. Air Water Borne Diseases, 2(109), 1–8.Google Scholar
- Cheng, V. C., Wong, S. S., Chen, J. H., Chan, J. F., To, K. K., Poon, R. W., et al. (2012). An unprecedented outbreak investigation for nosocomial and community-acquired legionellosis in Hong Kong. Chinese Medical Journal (Engl), 125(23), 4283–4290.Google Scholar
- Ditommaso, S., Giacomuzzi, M., Gentile, M., & Zotti, C. M. (2010). Evaluation of the usefulness of a new direct immunofluorescence assay (ScanVIT-Legionella) for monitoring hospital water systems contaminated with Legionella spp. Letters Applied Microbiology. doi: 10.1111/j.1472-765X.2010.02797.x.Google Scholar
- Lee, H. K., Shim, J. I., Kim, H. E., Yu, J. Y., & Kang, Y. H. (2010). Distribution of Legionella species from environmental water sources of public facilities and genetic diversity of L. pneumophila serogroup 1 in South Korea. Applied and Environmental Microbiology. doi: 10.1128/AEM.00422-10.Google Scholar
- Rakic, A., Peric, J., & Foglar, L. (2012). Influence of temperature, chlorine residual and heavy metals on the presence of Legionella pneumophila in hot water distribution systems. Annals of Agriculture and Environmental. Medicine, 19(3), 431–436.Google Scholar
- Serrano-Suarez, A., Dellunde, J., Salvado, H., Cervero-Arago, S., Mendez, J., Canals, O., et al. (2013). Microbial and physicochemical parameters associated with Legionella contamination in hot water recirculation systems. Environmental Science Pollution and Research International. doi: 10.1007/s11356-013-1557-5.Google Scholar
- Thomas, J. M. (2012). The risk to human health from free-living amoeba interactioin with Legionella in drinking and recycled water systems. Ph.D Thesis in New South Wels University.Google Scholar