scholarly journals Performance of Legiolert Test vs. ISO 11731 to Confirm Legionella pneumophila Contamination in Potable Water Samples

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 690 ◽  
Author(s):  
Maria Scaturro ◽  
Matteo Buffoni ◽  
Antonietta Girolamo ◽  
Sandra Cristino ◽  
Luna Girolamini ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Legionella Pneumophila ◽  
Water Samples ◽  
Gold Standard ◽  
Liquid Culture ◽  
Potable Water ◽  
Culture Method ◽  
Alternative Methods ◽  
Significant Difference

Detection and enumeration of Legionella in water samples is of great importance for risk assessment analysis. The plate culture method is the gold standard, but has received several well-known criticisms, which have induced researchers to develop alternative methods. The purpose of this study was to compare Legionella counts obtained by the analysis of potable water samples through the plate culture method and through the IDEXX liquid culture Legiolert method. Legionella plate culture, according to ISO 11731:1998, was performed using 1 L of water. Legiolert was performed using both the 10 mL and 100 mL Legiolert protocols. Overall, 123 potable water samples were analyzed. Thirty-seven (30%) of them, positive for L. pneumophila, serogroups 1 or 2–14 by plate culture, were used for comparison with the Legiolert results. The Legiolert 10 mL test detected 34 positive samples (27.6%) and the Legiolert 100 mL test detected 37 positive samples, 27.6% and 30% respectively, out of the total samples analyzed. No significant difference was found between either the Legiolert 10 mL and Legiolert 100 mL vs. the plate culture (p = 0.9 and p = 0.3, respectively) or between the Legiolert 10 mL and Legiolert 100 mL tests (p = 0.83). This study confirms the reliability of the IDEXX Legiolert test for Legionella pneumophila detection and enumeration, as already shown in similar studies. Like the plate culture method, the Legiolert assay is also suitable for obtaining isolates for typing purposes, relevant for epidemiological investigations.

Validation of the Legipid® Bioalarm Legionella Assay

2012 ◽  
Vol 95 (5) ◽  
pp. 1440-1451 ◽  
Author(s):  
Guillermo Rodríguez Albalat ◽  
Begoña Bedrina Broch ◽  
Marisa Jiménez Bono
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
False Positive Rate ◽  
False Negative ◽  
False Negative Rate ◽  
Reference Method ◽  
Culture Method ◽  
Magnetic Microspheres ◽  
Test Volume ◽  
Significant Difference

Abstract Legipid® Bioalarm Legionella is a test based on combined magnetic immunocapture and enzyme-immunoassay (CEIA) for the detection of Legionella pneumophila in water. Anti-L. pneumophila antibodies are immobilized on magnetic microspheres. Immunomagnetic analysis is applied to preconcentrated water samples in a final test volume of 9 mL. The method was compared with the standard culture method on both spiked and naturally contaminated water samples. The test was evaluated in potable, industrial, and natural water matrixes, according to the scope of the ISO 11731 reference method. These waters were tested with the target at levels ranging from low (10–99 CFU/mL) to high (100–999 CFU/mL); a Chi-square value of 1.8 indicated that there was no significant difference between the test and the reference method. The false-positive rate was 7%, and the false-negative rate 2%. For the inclusivity study, all 17 strains of L. pneumophila of different serogroups reacted with the test. For the exclusivity study, 17 strains of other Legionella species and 16 non-Legionella strains were tested. There were no cross-reactions with non-Legionella strains. L. beliardensis, L. adelaidensis, and one environmentally isolated Legionella sp. produced a positive result at high concentrations of 1800, 230, and 3900 CFU/mL, respectively. Agreement between the two methods was 95.9%.

scholarly journals Nosocomial legionella pneumonia: demonstration of potable water as the source of infection

1988 ◽  
Vol 101 (3) ◽  
pp. 647-654 ◽  
Author(s):  
B. Ruf ◽  
D. Schürmann ◽  
I. Horbrach ◽  
K. Seodel ◽  
H. D. Pohle
Keyword(s):  
Monoclonal Antibodies ◽  
Water Supply ◽  
Legionella Pneumophila ◽  
Water Samples ◽  
Potable Water ◽  
Supply System ◽  
University Hospital ◽  
Environmental Isolates ◽  
Legionella Pneumonia ◽  
Source Of Infection

SUMMARYFrom January 1983 until December 1985, 35 cases of sporadic nosocomial legionella pneumonia, all caused byLegionella pneumophila, were diagnosed in a university hospital.L. pneumophilaserogroup (SG) 1 was cultured from 12 of the 35 cases and compared to correspondingL. pneumophilaSG 1 isolates from water outlets in the patients' immediate environment by subtyping with monoclonal antibodies. The corresponding environmental isolates were identical to 9 out of 12 (75%) of those from the cases. However, even in the remaining three cases identical subtypes were found distributed throughout the hospital water supply. From the hospital water supply four different subtypes ofL. pneumophilaSG 1 were isolated, three of which were implicated in legionella pneumonia. Of 453 water samples taken during the study 298 (65.8%) were positive for legionellae. Species ofLegionellaother thanL. pneumophilahave not been isolated. This may explain the exclusiveness ofL.pneumophilaas the legionella pneumonia-causing agent. Our results suggest that the water supply system was the source of infection.

scholarly journals Evaluation of a most probable number method for the enumeration of Legionella pneumophila from North American potable and nonpotable water samples

2017 ◽  
Vol 16 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Ray Petrisek ◽  
Jonathon Hall
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Potable Water ◽  
High Specificity ◽  
Most Probable Number ◽  
Water Type ◽  
Probable Number ◽  
Standard Methods ◽  
Water And Wastewater ◽  
Higher Sensitivity

Abstract This study compares the performance of a novel most probable number (MPN) method (Legiolert™/Quanti-Tray®) with Standard Methods for the Examination of Water and Wastewater 9260 J for the enumeration of Legionella pneumophila from potable and nonpotable waters. Data from the study showed that Legiolert exhibited higher sensitivity for the detection of L. pneumophila for potable water and equivalent sensitivity for nonpotable water. The Legiolert medium had a high specificity with no false positive signals reported for either water type. The new method represents a significant improvement in usability and accuracy in the enumeration of L. pneumophila.

scholarly journals Comparison of Updated Methods for Legionella Detection in Environmental Water Samples

2021 ◽  
Vol 18 (10) ◽  
pp. 5436
Author(s):  
Daniela Toplitsch ◽  
Sabine Platzer ◽  
Romana Zehner ◽  
Stephanie Maitz ◽  
Franz Mascher ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Limit Of Detection ◽  
Culture Method ◽  
Environmental Water ◽  
Microbial Flora ◽  
Culture Methods ◽  
Outbreak Investigations ◽  
Standard Culture ◽  
Selection Of

The difficulty of cultivation of Legionella spp. from water samples remains a strenuous task even for experienced laboratories. The long incubation periods for Legionellae make isolation difficult. In addition, the water samples themselves are often contaminated with accompanying microbial flora, and therefore require complex cultivation methods from diagnostic laboratories. In addition to the recent update of the standard culture method ISO 11731:2017, new strategies such as quantitative PCR (qPCR) are often discussed as alternatives or additions to conventional Legionella culture approaches. In this study, we compared ISO 11731:2017 with qPCR assays targeting Legionella spp., Legionella pneumophila, and Legionella pneumophila serogroup 1. In samples with a high burden of accompanying microbial flora, qPCR shows an excellent negative predictive value for Legionella pneumophila, thus making qPCR an excellent tool for pre-selection of negative samples prior to work-intensive culture methods. This and its low limit of detection make qPCR a diagnostic asset in Legionellosis outbreak investigations, where quick-risk assessments are essential, and are a useful method for monitoring risk sites.

scholarly journals Health Risk Assessment of Arsenic in the Drinking Water of Upper Sindh, Pakistan

2021 ◽  
Vol 11 (5) ◽  
pp. 7558-7563
Author(s):  
N. U. H. Shar ◽  
G. Q. Shar ◽  
A. R. Shar ◽  
S. M. Wassan ◽  
Z. Q. Bhatti ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Drinking Water ◽  
Global Positioning System ◽  
Water Samples ◽  
Potable Water ◽  
Arsenic Content ◽  
Positioning System ◽  
Microwave Assisted ◽  
Global Positioning ◽  
Microwave Assisted Digestion

Water is a valuable compound for plants, animals, and humans. Various contaminating agents pollute it, with arsenic being one of them. Measurements of arsenic in potable water in Upper Sindh were conducted during this study. The samples were prepared by microwave-assisted digestion and analyzed by an atomic absorption spectrophotometer. A total of 240 potable water samples were collected from 8 Talukas of Upper Sindh. DMS coordinates were also recorded with the help of the Global Positioning System (GPS). The highest arsenic content of 50µg/L was observed in Garhi Khairo Taluka. The average arsenic content in water samples of all of the Talukas, except Miro Khan, was found higher than the WHO permissible limit. The 69.2% of samples were found to be contaminated by arsenic. Therefore, the water of the studied area is concluded to be in poor condition for cooking and drinking.

scholarly journals Legionellaceae in the potable water of Nova Scotia hospitals and Halifax residences

1994 ◽  
Vol 112 (1) ◽  
pp. 143-150 ◽  
Author(s):  
T. Marrie ◽  
P. Green ◽  
S. Burbridge ◽  
G. Bezanson ◽  
S. Neale ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Legionella Pneumophila ◽  
Water Samples ◽  
Potable Water ◽  
Calcium Content ◽  
Potassium Nitrate ◽  
Hot Water ◽  
Total System ◽  
Single Family ◽  
Water Heaters

SummaryWater was cultured from 39 of 48 hospitals (7 Halifax hospitals and 32 non-Halifax hospitals) in the province of Nova Scotia and from 90 residences (74 private dwellings, 16 apartments) in Halifax to determine the frequency of legionella contamination. Six of seven Halifax hospitals had Legionellaceae isolated from their potable water compared with 3 of 32 non-Halifax hospitals (P < 0.0001). Overall. 19 of 59 (32%) of the water samples from Halifax hospitals were positive for legionellae compared with 5 of 480 (1%) samples from non-Halifax hospitals (P < 0.0000). Five of the six positive Halifax hospitals hadLegionella pneumophilaserogroup 1 and 1 hadL. longbeachaeserogroup 2 recovered from their potable water. Legionella contamination was associated with older, larger (> 50 beds) hospitals with total system recirculation. These hospitals also had water with a higher pH and calcium content but lower sodium, potassium, nitrate, iron and copper content.Fourteen of the 225 (6.2%) water samples from Halifax residences were positive for legionellae – 8% (6/74) of the single family dwellings were positive, compared with 25% (4/16) apartments. The positivity rate of 15.7% for the 19 electric hot-water heaters in Halifax homes was not significantly different from the 32% positivity for Halifax hospitals.L. longbeachaeaccounted for 2 of the 14 isolates of legionellae from Halifax homes.

scholarly journals Comparison of two culture methods for the enumeration of Legionella pneumophila from potable water samples

2021 ◽  
Author(s):  
Laura A. Boczek ◽  
Min Tang ◽  
Casey Formal ◽  
Darren Lytle ◽  
Hodon Ryu
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Potable Water ◽  
High Sensitivity ◽  
High Specificity ◽  
The United States ◽  
Contaminated Water ◽  
Plumbing System ◽  
Culture Methods ◽  
False Negatives

Abstract Legionella infections have steadily increased in the United States over the last 20 years, and most of these infections have been attributed to contaminated water. The gold standard for confirmation of Legionella presence in water is culturing with Buffered Charcoal Yeast Extract (BCYE) agar. Following many modifications, this method is still time-consuming, expensive, and can take longer than 10 days for full confirmation. The Legiolert is a newer and simpler culture product that is claimed to be able to quantify Legionella pneumophila in 7 days with high sensitivity and specificity and does not need further confirmation for the presence of L. pneumophila. This study compared the culturability of L. pneumophila occurring in a simulated home plumbing system using both Legiolert and BCYE agar methods. Out of 185 water samples, Legiolert and BCYE method detected L. pneumophila in 83 and 85% of the samples, respectively. The two methods were determined to be statistically equivalent for culturability of L. pneumophila, though the detected levels by Legiolert were slightly higher than the BCYE method. The molecular confirmation of positive (n = 254) and negative wells (n = 82) with Legiolert also showed a high specificity of 96.5% (i.e., 3.5% false positives (9/254) and 0% false negatives (0/82)).

scholarly journals Assessing the viability of Legionella pneumophila in environmental samples: regarding the filter application of Ethidium Monoazide Bromide

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Michela Consonni ◽  
Anna Grassi ◽  
Stefania Scuri ◽  
Maria Gori ◽  
Elisabetta Tanzi ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Environmental Samples ◽  
Pure Water ◽  
Dna Amplification ◽  
Culture Method ◽  
Ethidium Monoazide ◽  
Cultivable Bacteria ◽  
Source Of Infection ◽  
Commercial Kit

Abstract Purpose Analyses of 34 water samples from 13 healthcare structures revealed how culture method and quantitative PCR (qPCR) often differ in the detection of Legionella pneumophila (Lp). With these considerations in hand, culture method, PCR and Ethidium Monoazide Bromide (EMA) qPCR have all been compared in order to detect Lp in water samples, identify a method able to speed up the procedures, detect the “viable but not cultivable” bacteria (VBNC) and exclude non-viable bacteria using a commercial kit for extraction and amplification as well as modification of the protocol. Methods Pure water samples artificially spiked with viable, non-viable and VBNC Lp ATCC 33152 were analyzed using a commercial kit for both qPCR and EMA-qPCR, while ISO 11731-2-2004 was used for culture method. Results Only 35% (12/34) of the environmental samples were positive in both culture and qPCR methods. With regard to EMA-qPCR, results showed the absence of dye toxicity on viable and VBNC strains and an incomplete effectiveness on the non-viable ones. In both viable and VBNC strains, a decrease of bacterial DNA amplification was recorded as a function of sample dilution but not of EMA concentration. Conclusions Discrepancies between culture method and EMA-qPCR were observed and may be due to different causes such as membrane-dye interactions, presence of interfering compounds and the sensitivity of the kit used. Study significance and impact In the presence of one or more suspected cases of nosocomial legionellosis, the application of a rapid molecular method able to identify only the viable and VBNC Lp would be useful in order to quickly identify the source of infection and to intervene with sanitation treatments. However, seeing that in our experience EMA pretreatment on the filter membrane did not come up with the expected results, it would be necessary to proceed with other experiments and/or different dyes. Graphical Abstract

scholarly journals Assessment of Viability of Legionella Pneumophila in Environmental Samples: On Filter Application of Ethidium Monoazide Bromide

2021 ◽  
Author(s):  
Michela Consonni ◽  
Anna Grassi ◽  
Stefania Scuri ◽  
Maria Gori ◽  
Elisabetta Tanzi ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Environmental Samples ◽  
Dna Amplification ◽  
Culture Method ◽  
Environmental Water ◽  
Ethidium Monoazide ◽  
Cultivable Bacteria ◽  
Source Of Infection ◽  
Commercial Kit

Abstract Purpose: Culture method, Real-Time PCR (qPCR) and Ethidium Monoazide Bromide (EMA) qPCR have been compared in order to detect Legionella pneumophila (Lp) in water samples, to identify a method able to speed up the procedures, detect the “viable but not cultivable” bacteria (VBNC) and exclude dead bacteria using a commercial kit for extraction and amplification and modifying the protocol.Methods: Using these three methods, 34 environmental water samples and a series of samples artificially spiked with alive, dead and VBNC Lp ATCC 33152 were analysed. ISO 11731-2-2004 culture method was applied, whereas a commercial kit was selected for both qPCR and EMA qPCR pretreatment.Results: only 35% (12/34) of the environmental samples were positive in both culture and qPCR methods. With regard to EMA qPCR, results showed the absence of dye toxicity on viable and VBNC strains and an incomplete effectiveness on the dead ones. In both viable and VBNC strains a decrease of bacterial DNA amplification was recorded as a function of sample dilution but not of EMA concentration.Conclusions: Discrepancies between culture method and EMA-qPCR were observed and could be due to different causes as membrane-dye interactions, presence of interfering compounds and the relatively low sensitivity of the kit used.Significance and Impact of the Study: In presence of one or more suspected cases of nosocomial legionellosis, the application of a rapid molecular method able to identify only the viable and VBNC Lp would be useful in order to quickly identify the source of infection and to intervene with sanitation treatments. However, because in our experience EMA pretreatment on filter membrane has not given the expected results, it would be necessary to proceed with other experiments and different dyes.

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