DETECTION OF BACTERIAL-DNA POLYMERASE CHAIN-REACTION PRODUCTS BY MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY

Accurate monitoring and identification of Legionella species, the caus ative agents of Legionnaires' and other diseases, in environmental wat er sources is an important public health issue, Traditional culture me thods often lack the sensitivity and specificity that can be attained using the polymerase chain reaction (PCR) to amplify targeted regions of the bacterial genome, Matrix-assisted laser desorption/ionization c ombined with time-of-flight (MALDI-TOF) mass spectrometry is shown to be useful for detection of 108- and 168-base PCR products specific to Legionella. A rapid purification aimed at removal of salts and unreact ed primers is demonstrated. The addition of a synthetic DNA 20-mer to the MALDI sample facilitates aiming the laser at a favorable spot on t he sample probe from which the PCR products can be detected.