[New approaches to detection of legionellosis causative agents in clinical samples and environment objects by PCR].

AIM: Selection of perspective targets as a base for development of test systems for the detection of legionella DNA in study material by PCR with electrophoresis and hybridization-fluorescent accounting of the results. MATERIALS AND METHODS: 22 Legionella pneumophila, 3 Legionella spp. strains and 30 cultures ofheterologic microorganisms, clinical material and environmental object samples were used in the study. Genome analysis was carried out by using Mega 3.1 program. Primer selection was conducted by using Primer Express program and BLAST algorithm and TaqMan format probes on the website www.genscript.com. RESULTS: Analysis of 712 legionella nucleotide sequences for the presence of novel species-specific and conservative for L. pneumophila loci was carried out. Fragments of life-support genes were selected for the analysis: fliC, mompS, ftsZ, dotA, dnaX, trpS, rpoB, rnp, proA, gspA. The most perspective DNA targets were established to be ftsZ and mompS genes. Based on the selected loci, PCR test systems were constructed for the detection of DNA oflegionella causative agent in biological material and environment objects, their diagnostic value was characterized. CONCLUSION: The studies carried out have shown the perspective of use of life-support ftsZ and mompS genes for the construction of novel preparations for legionellosis genetic diagnostics.

[Development and use of the assay for Legionella pneumophila detection based on fluorescent real-time/endpoint polymerase-chain reaction].

The aim of the work was to develop a PCR-based assay for detection of L. pneumophila and L. micdadei in environmental samples as well as in clinical samples from low respiratory tract and to assess its analytic characteristics. The assay was used during investigation of the outbreak developed in July 2007 in town Verkhnyaya Pyshma (Sverdlovsk region). Polymerase-chain reaction (PCR)with fluorescent detection,sequencing and cloning of DNA fragments were used. Developed assay based on the PCR with fluorescent real-time/ endpointdetection is able to detect L. pneumophila in clinical and environmental samples and to quantify amount of bacterial DNA in water. Specificity of analysis (100%) was assessed using the panel of bacterial strains and samples from healthy individuals. Analytic sensitivity of assay and quantitation limit was 1000 GU in 1 ml. Sensitivity of the assay of artificially contaminated biological samples was 1000 bacteria in 1 ml. During outbreak investigation L. pneumophila DNAwas detected in 4 lung samples from 4 fatal cases, from 1 of 2 sputum samples, 1 of 2 bronchoalveolar lavage samples with X-ray confirmed pneumonia. Legionella's DNA was found in samples from cooling towers, central hot water supply as well as from showerheads in apartments of 3 patients. Fountain and drinking water samples were PCR-negative. Specificity of PCR-positive results was confirmed by sequencing. Use of the assay during outbreak in- vestigation allowed to confirm the diagnosis in fatal cases and quickly identify the possible source of infection.