DETECTION AND IDENTIFICATION OFLegionellaSPECIES FROM GROUNDWATERS

Abstract

Legionellae are opportunistic bacterial pathogens causing Legionnaires' disease and Pontiac fever and are ubiquitous in surface waters and in infrastructure to contain or distribute water, including pipes, cooling towers, and whirlpool spas. Infection in community-acquired and nosocomial outbreaks is by exposure to contaminated aerosols. Little is known about the presence of legionellae in groundwater. This study used samples from various locations in the United States and Canada to determine if legionellae could be isolated from water and biofilms derived from groundwaters not known to be under the direct influence of surface water. Of the 114 total samples of water and biofilm tested, 29.1% and 28.2% were positive for Legionella by cultivation and polymerase chain reaction (PCR), respectively. Legionellae were found in both warm and colder groundwaters, with more isolates from samples incubated at 30 degrees C than the 35 degrees C conventional temperature for Legionella isolation. The concentration of Legionella found in the water samples ranged from 10(2) to 10(5) CFU/L and up to 1.2 x 10(2) CFU/cm(2) in the biofilm. The species of Legionella identified included both known pathogenic species and species that have not yet been identified as human pathogens. Millions of people in Canada, and around the world, rely on groundwater as their source for drinking. This study shows that legionellae are widespread in groundwater and have the potential to seed derived water supplies and biofilms in public distribution systems. This further widens the known sphere of Legionella colonization and the implications of its presence for public health.

Legionella anisa , a Possible Indicator of Water Contamination by Legionella pneumophila

“…The available evidence is consistent with this second hypothesis, although bacterial competition may have played a role in the emergence of more resistant L. pneumophila. (i) L. pneumophila is often found with Legionella species other than L. pneumophila in water (5,8,9,17,25). (ii) An outbreak of Legionnaires' disease caused by L. pneumophila, despite the identification of only L. anisa in tap water, was reported in a previous study (26).…”

“…Legionella species are ubiquitous in many water systems (6,8,9,17,22,27)-including hospital water systems (30,31,39)-with Legionella pneumophila and Legionella species other than L. pneumophila isolated together (3,11) or alone (19,37). The most frequent species are L. pneumophila and L. anisa (5,12,16,18,36).…”

Review: Microbial biocenoses in pristine aquifers and an assessment of investigative methods

“…Faecal bacteria may also occur in pristine ground and surface waters that are not impacted by human activity; they can be attributed to wild animals (Niemi and Niemi 1991). Recent research revealed that small numbers of microbial pathogens, such as Legionella, might be detectable in pristine waters without any discernible contamination source, and without the presence of faecal indicator bacteria (Brooks et al 2004;Schaffter et al 2004). In some cases, microbial pathogens thus seem to be part of the "natural" biocenosis in groundwater.…”

Occurrence and Genetic Diversity of Uncultured Legionella spp. in Drinking Water Treated at Temperatures below 15°C

“…L. pneumophila has been detected only sporadically by use of the cultivation method in untreated groundwater (GW) and in treated water at temperatures below 20°C (4,14,20,24,56). However, cultivation-independent techniques, including immunological methods, fluorescent in situ hybridization (FISH), and PCR-based methods, clearly revealed the common presence of Legionella species in aquatic environments, even at temperatures below 20°C (11,12,14,44,50). In addition, FISH methods showed that undefined Legionella species may represent up to 7% of biofilms grown in treated water (52).…”