Legionella Detection in Water Networks as per ISO 11731:2017: Can Different Filter Pore Sizes and Direct Placement on Culture Media Influence Laboratory Results?

Osvalda De Giglio, Giusy Diella, Paolo Trerotoli, Michela Consonni, Roberta Palermo, Marina Tesauro, Pasqualina Laganà, Gabriella Serio and Maria Teresa Montagna
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Osvalda De Giglio: Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Department of Biomedical Science and Human Oncology, Section of Hygiene, University of Bari Aldo Moro, 70124 Bari, Italy
Giusy Diella: Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Department of Biomedical Science and Human Oncology, Section of Hygiene, University of Bari Aldo Moro, 70124 Bari, Italy
Paolo Trerotoli: Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, 70124 Bari, Italy
Michela Consonni: Department of Biomedical Surgical and Dental Sciences, University of Milan, 20133 Milan, Italy
Roberta Palermo: Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, 98125 Messina, Italy
Marina Tesauro: Department of Biomedical Surgical and Dental Sciences, University of Milan, 20133 Milan, Italy
Pasqualina Laganà: Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, 98125 Messina, Italy
Gabriella Serio: Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, 70124 Bari, Italy
Maria Teresa Montagna: Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Department of Biomedical Science and Human Oncology, Section of Hygiene, University of Bari Aldo Moro, 70124 Bari, Italy

IJERPH, 2020, vol. 17, issue 6, 1-8

Abstract: Determination of Legionella concentrations in water networks is useful for predicting legionellosis risks. The standard culture technique using concentration with membranes filters is the most commonly used method for environmental surveillance of Legionella . The aim of this study was to verify whether filtration with different filter pore sizes (0.2 and 0.45 µm) according to (ISO) 11731:2017, followed by directly placing them on culture media, can influence Legionella detection. Three laboratories participated in an experimental study that tested a known suspension of Legionella pneumophila ( Lpn ) serogroup 1 (ATCC 33152) (approximate final cell density of 15 CFU/mL). E. coli (ATCC 11775) and Pseudomonas aeruginosa (ATCC 25668) were included as control tests. The average (95% CI) percentage of recovery of Lpn was 65% using 0.45-µm filters and 15% using 0.2-µm filters ( p < 0.0001). For control tests, the average (95% CI) percentage of recovery was higher with 0.45 vs. 0.2 µm filters: 97% vs. 64% for Escherichia coli ( p < 0.00001) and 105% vs. 97% ( p = 0.0244) for P. aeruginosa . Our results showed that the 0.45-µm filters provided the greatest detection of Legionella . Because the current national guidelines leave the choice of membrane porosity to the operator, experimental studies are important for directing operators towards a conscious choice to standardize Legionella environmental surveillance methods.

Keywords: membrane filters; Legionella; ISO 11731:2017; environmental surveillance (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
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