A number of 192 samples (180 water & swab specimens and 12 patient sputa)
were chosen from different sites of Mansoura University Hospitals for detection and
diagnosis of Legionella pneumophila. Out of the 192 samples, 148 were positive by
culture method and non-specific staining technique such as gram staining and
biochemical analysis. In our trials for diagnosis of Legionella pneumophila, we
found that 107 of 148 samples were positive by slide agglutination test and 110
samples were positive by direct immunoflourescence assay, while 130 samples were
positive by polymerase chain reaction (PCR) technique which proved to be the most
specific and sensitive technique for diagnostic investigation of L. pneumophila. The
results show that the four disinfectant procedures (chlorine, ozone, U.V. light and
heat) were effective in eradicating Legionella pneumophila from different water
samples. Both UV light and heat (60ºC) produced a 5 log kill in less than 1 h. In
contrast, both chlorine and ozone required 5 h of exposure to produce a 5 log
decrease. Neither turbidity nor the higher temperature of 43ºC impaired the efficacy
of any of the disinfectant methods.