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Hot Water Systems with Low Concentrations of Legionellae May Be a Risk on Cruise Ships, Page 1 of 2
< Previous page Next page > /docserver/preview/fulltext/10.1128/9781555817985/9781555812300_Chap71-1.gif /docserver/preview/fulltext/10.1128/9781555817985/9781555812300_Chap71-2.gifAbstract:
Water systems contaminated with legionellae cause outbreaks and sporadic cases of Legionella pneumonia. Legionellae are ubiquitous in water systems. In most clinical cases the source of infection can be confirmed only by using typing methods that discriminate between the patient and the environmental isolates. Water samples were analyzed using Legionella isolation standard method ISO 11731, completed by additional concentration with centrifugation (6,000 X g, 10 min). The legionella concentrations varied from 5 to 2,000 CFU/liter; the highest concentration was found in the tap water sample. The strains were L. pneumophila serogroup 1. The thermophilic heterotrophic bacteria concentration was highest (3.0 X 106 CFU/liter) in the tap water sample that contained the highest legionella counts. The mesophilic bacteria content was the highest in the legionella positive shower sample (5.9 X 107 CFU/liter). The L. pneumonia case of the 61-year-old man was detected only by the urinary antigen method. Therefore, conclusive evidence of the source of this particular infection could not be confirmed. Since the incubation time for legionella infection can vary from 2 to 10 days, it is possible that the infection was contracted elsewhere, such as the patient's home.