title: Fast immunosensing technique to detect Legionella pneumophila in different natural and anthropogenic environments: comparative and collaborative trials.
abstract: BACKGROUND
  Legionellosis is an uncommon form of pneumonia. After a clinical encounter, the necessary antibiotic treatment is available if the diagnosis is made early in the illness. Before the clinical encounter, early detection of the main pathogen involved, Legionella pneumophila, in hazardous environments is important in preventing infectious levels of this bacterium. In this study a qualitative test based on combined magnetic immunocapture and enzyme-immunoassay for the fast detection of Legionella pneumophila in water samples was compared with the standard method, in both comparative and collaborative trials. The test was based on the use of anti-Legionella pneumophila antibodies immobilized on magnetic microspheres. The final protocol included concentration by filtration, resuspension and immunomagnetic capture. The whole assay took less than 1 hour to complete.
  
  
  RESULTS
  A comparative trial was performed against the standard culture method (ISO 11731) on both artificially and naturally contaminated water samples, for two matrices: chlorinated tap water and cooling tower water. Performance characteristics of the test used as screening with culture confirmation resulted in sensitivity, specificity, false positive, false negative, and efficiency of 96.6%, 100%, 0%, 3.4%, and 97.8%, respectively. The detection limit at the level under which the false negative rate increases to 50% (LOD50) was 93 colony forming units (CFU) in the volume examined for both tested matrices. The collaborative trial included twelve laboratories. Water samples spiked with certified reference materials were tested. In this study the coincidence level between the two methods was 95.8%.
  
  
  CONCLUSIONS
  Results demonstrate the applicability of this immunosensing technique to the rapid, simple, and efficient detection of Legionella pneumophila in water samples. This test is not based on microbial growth, so it could be used as a rapid screening technique for the detection of L. pneumophila in waters, maintaining the performance of conventional culture for isolation of the pathogen and related studies.
authors.affiliation: Biótica, Bioquímica Analítica, S.L, Science and Technology Park of Jaume I University, Campus Riu Sec - Espaitec 2, planta baja, E12071, Castellón de la Plana, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Bedrina
authors.forename: Sonia
authors.initials: S
authors.lastname: Macián
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Solís
authors.forename: Roberto
authors.initials: R
authors.lastname: Fernández-Lafuente
authors.forename: Eva
authors.initials: E
authors.lastname: Baldrich
authors.forename: Guillermo
authors.initials: G
authors.lastname: Rodríguez
mesh_terms: D000907:Antibodies, Bacterial; D001431:Bacteriological Techniques / Q000379:methods*; D003951:Diagnostic Errors; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods; D016952:Legionella pneumophila / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013997:Time Factors; D014871:Water Microbiology
chemical_list: D000907:Antibodies, Bacterial