Development of a DNA microarray for detection and identification of Legionella pneumophila and ten other pathogens in drinking water

The safety and accessibility of drinking water are major concerns throughout the world. Consumption of water contaminated with infectious agents, toxic chemicals or radiological hazards represents a significant health risk and is strongly associated with mortality. Therefore, we have developed an oligonucleotide-based microarray using the sequences of 16S-23S rDNA internal transcribed spacer regions (ITS) and the gyrase subunit B gene (gyrB) found in the most prevalent and devastating waterborne pathogenic agents. This new diagnostic contains 26 specific probes and can simultaneously detect Aeromonas hydrophila, Klebsiella pneumoniae, Legionella pneumophila, Pseudomonas aeruginosa, Salmonella spp., Shigella spp., Staphylococcus aureus, Vibrio choleraeo, Vibrio parahaemolyticus, Yersinia enterocolitica and Leptospira interrogans. Testing was carried out against a total of 218 bacterial strains, including 53 representative strains, 103 clinical isolates and 62 strains of other bacterial species belonging to 10 genera and 48 species. The results were specific and reproducible, with a detection sensitivity of 0.1 ng DNA or 10⁴ CFU/ml achieved for pure cultures of each target organism. The diluted cultures and real drinking water samples were tested by the microarray with 100% accuracy. This novel diagnostic method is superior in time- and labor-efficiency to conventional bacterial culture and antiserum agglutination, and can be readily applied to epidemiological surveillance and other food safety applications.