Inter-laboratory validation of a rapid assay for the detection and quantification of Legionella spp. in water samples.
OBJECTIVE
To compare the standard culture method with a new, rapid test (ScanVIT-Legionella™) using fluorescently labelled gene probes for the detection and enumeration of Legionella spp. The new technique was validated through experiments conducted on both artificially and naturally contaminated water and through an inter-laboratory comparison.


RESULTS
All samples were processed by the ScanVIT test according to the manufacturer's instructions and by a culture method (ISO 11731). ScanVIT detected significantly more positive samples, although concentrations were similar and a strong positive correlation between the two methods was observed (r = 0.888, P < 0.001). The new test was more accurate in identifying the co-presence of Legionella pneumophila and Leg. non-pneumophila. ScanVIT showed a slightly higher Legionella recovery from water samples artificially contaminated with Leg. pneumophila alone or together with Pseudomonas aeruginosa. Lastly, the inter-laboratory comparison revealed that the ScanVIT test exhibits a lower variability than the traditional culture test (mean coefficient of variation 8.7 vs 16.1%).


CONCLUSIONS
The results confirmed that the ScanVIT largely overlaps the reference method and offers advantages in terms of sensitivity, quantitative reliability and reduced assay time.


CONCLUSIONS
The proposed method may represent a useful validated alternative to traditional culture for the rapid detection and quantification of Legionella spp. in water.
Bargellini
A
A
Department of Public Health Sciences, University of Modena and Reggio Emilia, Modena, Italy. annalisa.bargellini@unimore.it
Marchesi
I
I
Leoni
E
E
Mansi
A
A
Cristino
S
S
Marcelloni
A M
AM
Borella
P
P
D001431:Bacteriological Techniques; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media; D015342:DNA Probes; D005456:Fluorescent Dyes; D007753:Laboratories; D007875:Legionella / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016952:Legionella pneumophila / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D015588:Observer Variation; D016133:Polymerase Chain Reaction / Q000379:methods; D015203:Reproducibility of Results; D013045:Species Specificity; D013997:Time Factors; D014871:Water Microbiology; D014876:Water Pollution; D014881:Water Supply
D003470:Culture Media; D015342:DNA Probes; D005456:Fluorescent Dyes