Ff. Reinthaler et al., COMPARATIVE-STUDY OF PROCEDURES FOR ISOLATION AND CULTIVATION OF LEGIONELLA-PNEUMOPHILA FROM TAP WATER IN HOSPITALS, Journal of clinical microbiology, 31(5), 1993, pp. 1213-1216
For the isolation and cultivation of Legionella Pneumophila from tap w
ater in hospitals, we compared different media and selection technique
s. A second part of the study compared the L. pneumophila yields from
different water samples at identical sites. A total of 210 water sampl
es (500 ml each) were collected from two selected sites in each of 21
hospitals. Warm water samples were collected after flow times of 0, 5,
10, and 15 min; in addition, one cold water sample was collected. Fil
tration was used to concentrate all samples. Following filtration, 0.1
and 1 ml each of untreated samples, heat-treated samples (3 min, 59-d
egrees-C), and acid-treated samples (pH 2.2, 15 min) were spread onto
the selective media MWY, (SR 118; Oxoid) and BMPAalpha (SR 111; Oxoid)
, and samples from 12 hospitals were also spread onto GVPC medium (SR
152; Oxoid). A total of 72 (34%) of the 210 samples from 12 hospitals
were positive. With respect to the positive Legionella cultures, there
was no significant difference between the selective media MWY, BMPAal
pha, and GVPC. With the BMPAalpha supplement, more samples were positi
ve following heat treatment (P < 0.05) or acid treatment (P < 0.05) th
an without any further treatment. For the maximum yield of Legionella
colonies with minimum additional microbial flora, acid treatment was t
he most effective, and by all methods, the GVPC supplement was the mos
t selective. For routine water tests in hospitals for differentiating
between systemic and local contamination, acid treatment of the concen
trated samples, the use of different selective media, and the correct
selection of sampling sites are recommended.