Legionella spp., amoebae and not-fermenting Gram negative bacteria in an Italian university hospital water system

Introduction: In hospital and other health care facilities, contamination of water systems by potentially infectious microorganisms, such as bacteria, viruses and protozoa, is a source of nosocomial infections, which may originate from colonization of water pipes, cooling towers, spa pools, faucets, showers, water supplies. Objective: This study focused on the occurrence of Legionella spp., free-living amoebae and not-fermenting Gram-negative microorganisms in a University hospital water system located in the town of Messina (Sicily, Italy), never examined before. Materials and Methods: From January 2008 to March 2009, hot tap water samples were collected from 10 wards. Legionella spp. recovered on selective culture medium were identified by microagglutination latex test; free-living amoebae were cultured using Escherichia coli as a food source. Not-fermenting Gram negative microorganisms were identified by API 20 NE strips. Results: Legionella spp. were found in 33.33% of the samples. L. pneumophila serogroup 1 was recovered from Laboratory Diagnostic and Anaesthesia-Neurology wards, with a peak of 3.5 x 104 cfu/L in May '08. L. pneumophila serogroups 2-14 were found in Otorhinolaryngology, Pathologic Anatomy, Pediatrics and Surgery wards, and peaked (4 x 104 cfu/L) in Apr '08. Pseudomonadaceae and Hyphomycetes were also detected. Legionella spp. were recovered from samples positive for not-pathogenic amoebae Hartmannella spp. Conclusion: This first study of a Messina hospital water system suggested potential health risks related to the detection of Hartmannella spp., as reservoirs for Legionella spp., and Pseudomonas aeruginosa, a Gram negative not-fermenting bacterium frequently causing nosocomial pneumonia. Urgent need for monitoring programs and prevention measures to ensure hospital water safety is stressed.