title: Microbial and physicochemical parameters associated with Legionella contamination in hot water recirculation systems.
abstract: Hot water recirculation systems (HWRS) in hotels and nursing homes, which are common in countries such as Spain, have been related to outbreaks of legionellosis. To establish the relationships of microbial and physicochemical parameters, especially protozoa, with the occurrence of Legionella in HWRS, 231 samples from hotels and nursing homes were analysed for Legionella, protozoa, heterotrophic plate counts (HPC) at 22 and 37 °C, Pseudomonas, metals, temperature and others. Legionella pneumophila was the dominant species isolated, and 22 % were sg. 1. The sampling method became particularly important in order to define which factors were involved on the occurrence of Legionella. Results showed that the bacteria and the accompanying microbiota were more abundant in the first flush water whose temperature was lower. The bacteria occurred in those samples with high HPC and were inversely correlated with high temperatures. Multivariate regression showed that a concentration above 1 × 10(5) CFU/100 mL of HPC at 37 °C, Fe above 0.095 ppm and the presence of protozoa increased significantly the risk of Legionella colonization, while univariant regression showed that the presence of Cu above 0.76 ppm and temperature above 55 °C diminished it. Therefore, to reduce the risk associated with Legionella occurrence in HWRS these parameters should be taken into consideration.
authors: Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.
authors: Alejandra
authors: A
authors: Serrano-Suárez
authors: Jordi
authors: J
authors: Dellundé
authors: Humbert
authors: H
authors: Salvadó
authors: Sílvia
authors: S
authors: Cervero-Aragó
authors: Javier
authors: J
authors: Méndez
authors: Oriol
authors: O
authors: Canals
authors: Silvia
authors: S
authors: Blanco
authors: Antoni
authors: A
authors: Arcas
authors: Rosa
authors: R
authors: Araujo
mesh_terms: D058491:Bacterial Load; D002713:Chlorine / Q000032:analysis; D003300:Copper / Q000032:analysis; D006358:Hot Temperature; D007501:Iron / Q000032:analysis; D016952:Legionella pneumophila / Q000235:genetics / Q000302:isolation & purification*; D009735:Nursing Homes; D011549:Pseudomonas / Q000302:isolation & purification; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D013030:Spain; D014871:Water Microbiology; D014873:Water Pollutants / Q000302:isolation & purification*; D015032:Zinc / Q000032:analysis
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014873:Water Pollutants; D002713:Chlorine; D003300:Copper; D007501:Iron; D015032:Zinc