[Features of legionella biofilm formation in artificial and natural water systems].

AIM: Study the ability to form monospecies and associative biofilms as a characteristic oflegionella strains and features of organization of natural legionella biofilms in potentially dangerous water systems. MATERIALS AND METHODS: Comparative evaluation ofthe ability of 28 strains of Legionella spp. to form biofilms was determined in water according to previously developed procedure. Samples from biofilm of industrial enterprise coolers and systems of hot water supply of public buildings (hotels, trade centers, hospitals) were studied. Biofilms were studied by scanning and transmission electron microscopy methods. RESULTS: Legionella strains are divided into 3 groups by the ability to form biofilms. L. pneumophila BLR-05 strain that has the most pronounced ability to form monospecies biofilm and persistence in association with Pseudomonas aeruginosa was detected. Formation of massive legionella biofilm in association with bacteria of other taxonomic groups was detected on protective antibacterial filters in the system of hot water supply of a department of a therapeutic prophylaxis institution in the course of 2-3 weeks. Legionella biofilms on the surface of coolers resemble an aggregate of fungi, bacteria and blue-green algae enclosed into matrix. CONCLUSION: The ability to form artificial monospecies and associative biofilm may be a useful characteristic of legionella strains for evaluation of their adhesion and be used to evaluate epidemiological significance of the isolated strains. Prevention of formation of natural legionella biofilms in potentially dangerous water systems is necessary as an essential component of modern strategy of legionellosis prophylaxis.

[Prevalence of glucosyl transferase Lgt among Legionella pneumophila strains isolated from various sources].

AIM: Determine various members of Lgt glucosyl transferase family among microorganisms of Legionellaceae genus from museum collection and legionellae strains recently isolated in the Russian Federation and Germany. MATERIALS AND METHODS: Presence of 3 types of glucosyl transferase were determined in 73 strains of L. pneumophila and Legionella spp. Glucosyl transferase activity of 3 types (Lgt1, Lgt2 and Lgt3) was determined by western blotting and PCR method. RESULTS: Lgt1 and Lgt3 were detected only in members of L. pneumophila independently of isolation source and were absent in Legionella spp. strains. Lgt2 is absent in Legionella spp. strains and is detected in not all the L. pneumophila strains. Comparative analysis of detection frequency of Lgt2 in clinical strains and L. pneumophila strains isolated from the environment showed that the protein is detected in clinical strains more frequently (46%) compared with strains from the environment (23%). CONCLUSION: Lgt1 and Lgt3 as species specific markers could be used for practical purposes for identification of L. pneumophila strains. High frequency of Lgt2 isolation in clinical strains of L. pneumophila isolated from lung tissue in lethal cases of legionellosis compared with strains isolated from the environment requires a more detailed study of functional activity and substrate specificity of the glucosyl transferase.

[Serologic characteristic of Legionella pneumophila strains isolated from potentially dangerous water systems in Russian Federation in 2007 - 2011].

AIM: Study serologic diversity of Legionella pneumophila strains circulating in potentially dangerous water systems in Russian Federation by using an international panel of monoclonal antibodies. MATERIALS AND METHODS: Serotyping of 234 L. pneumophila strains isolated from coolers of industrial facilities and systems of hot water supply in Russian Federation in 2007 - 2011 was performed by enzyme immunoassay by using an international panel of monoclonal antibodies. RESULTS: Membership of the isolated strains in 14 L. pneumophila serogroups and in 7 subgroups of serogroup 1 was established. Among the isolated cultures serogroup 1 and 6, and Oxford and Heysham subgroup strains were predominant. L. pneumophila serogroup 1 strains were predominant in cooler water, and serogroup 6--in the hot water supply systems. 7 L. pneumophila strains of the serogroup 1 were typed by monoclone MAb 3/1 associated with LPS epitope that is characteristic for the most epidemically significant legionella strains. CONCLUSION: Typing by using international panel of monoclonal antibodies for characteristic and evaluation of epidemical significance of legionella strains being isolated form potentially dangerous water systems is the most informative and methodically accessible to a wide range of biological laboratories.

[Rate and level of contamination of potentially dangerous water supply facilities in Moscow region by Legionella pneumophila].

AIM: To assess rate and level of contamination by Legionella pneumophila of cooling water systems in industrial facilities as well as hot water supply systems of administrative buildings in Moscow region. MATERIALS AND METHODS: Cooling water systems of 8 industrial facilities and hot water supply systems of 12 administrative buildings or complexes located in Moscow or Moscow region were examined. Samples of water, washes and biofilms were studied by bacteriologic methods and RT-PCR. Results. Significant level of contamination of water systems by L. pneumophila was revealed in examined objects. Rate of contamination of cooling water systems in industrial facilities was 70%. The agent was detected in stagnant, end-capped, and rarely used segments of all hot water supply systems during decrease of water temperature to 36-52 degrees C. Visual detection of natural biofilms on the object correlated with high concentration of L. pneumophila in water samples. In some cases, associations of L. pneumophila with Pseudomonas aeruginosa were detected, including water samples from supply systems of 2 healthcare facilities. CONCLUSION: Obtained results confirm the importance of implementation of modem concept of legionellosis prevention in our country, based on regular quantitative monitoring for Legionella in potentially dangerous water objects and conduction of preventative measures if contamination exceeds acceptable level.