EVALUATION OF A NEW VERSION OF THE ENVIROAMP(TM) LEGIONELLA KIT FOR THE DETECTION OF LEGIONELLAE IN WATER SAMPLES BY THE POLYMERASE CHAIN-REACTION

The detection of Legionella sp. in various types of environmental wate r samples was evaluated using a revised version of the EnviroAmp(TM) L egionella kit (Perkin-Elmer), which is based on the polymerase chain r eaction (PCR). The new kit employs a modified protocol for the pretrea tment of water samples, which is designed to further reduce the inhibi tory action of some samples to the PCR. The results of the new kit wer e compared with those of culture. Seventy-four water samples were exam ined. Of these samples, 51 were taken from hospital water systems, 16 were household water samples, 5 were from surface water, and 2 were ra in water. These samples were examined both by PCR and by culture on MW Y Legionella selective agar. Of the 74 samples, 46 (62%) were positive by both test systems. Twenty-five samples (34%) were positive by PCR, but negative by culture. While 3 samples (4%) were negative by both t est methods, no sample was negative by PCR and positive by culture. St atistical analysis revealed high positive predictive values of PCR, wh en L. pneumophila was detected or when the genus Legionella was detect ed at high intensity. Negative predictive values were high, when the P CR was negative or only weakly positive for the genus Legionella.