1
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Warmt C, Nagaba J, Henkel J. Comparison of pre-labelled primers and nucleotides as DNA labelling method for lateral flow detection of Legionella pneumophila amplicons. Sci Rep 2024; 14:5018. [PMID: 38424185 PMCID: PMC10904838 DOI: 10.1038/s41598-024-55703-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/27/2024] [Indexed: 03/02/2024] Open
Abstract
Labelling of nucleic acid amplicons during polymerase chain reaction (PCR) or isothermal techniques is possible by using both labelled primers and labelled nucleotides. While the former is the widely used method, the latter can offer significant advantages in terms of signal enhancement and improving the detection limit of an assay. Advantages and disadvantages of both methods depend on different factors, including amplification method, detection method and amplicon length. In this study, both methods for labelling PCR products for lateral flow assay (LFA) analysis (LFA-PCR) were analysed and compared. It was shown that labelling by means of nucleotides results in an increase in label incorporation rates. Nonetheless, this advantage is negated by the need for post-processing and competitive interactions. In the end, it was possible to achieve a detection limit of 3 cell equivalents for the detection of the Legionella-DNA used here via primer labelling. Labelling via nucleotides required genomic DNA of at least 3000 cell equivalents as starting material as well as an increased personnel and experimental effort.
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Affiliation(s)
- Christian Warmt
- Fraunhofer Institute for Cell Therapy and Immunology - Bioanalytics and Bioprocesses (IZI-BB), 14476, Potsdam, Germany.
| | - Jette Nagaba
- Fraunhofer Institute for Cell Therapy and Immunology - Bioanalytics and Bioprocesses (IZI-BB), 14476, Potsdam, Germany
| | - Jörg Henkel
- Fraunhofer Institute for Cell Therapy and Immunology - Bioanalytics and Bioprocesses (IZI-BB), 14476, Potsdam, Germany
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2
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Yin X, Chen YZ, Ye QQ, Liao LJ, Cai ZR, Lin M, Li JN, Zhang GB, Peng XL, Shi WF, Guo XG. Detection performance of PCR for Legionella pneumophila in environmental samples: a systematic review and meta-analysis. Ann Clin Microbiol Antimicrob 2022; 21:12. [PMID: 35303873 PMCID: PMC8934000 DOI: 10.1186/s12941-022-00503-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 03/07/2022] [Indexed: 11/25/2022] Open
Abstract
Background Legionellosis remains a public health problem. The most common diagnostic method to detect Legionella pneumophila (L. pneumophila) is culture. Polymerase chain reaction (PCR) is a fast and accurate method for this detection in environmental samples. Methods Four databases were searched for studies that evaluated the detection efficiency of PCR in L. pneumophila. The quality evaluation was conducted using Review Manager 5.3. We used Meta-DiSc 1.4 software and the Stata 15.0 software to create forest plots, a meta-regression, a bivariate boxplot and a Deeks’ funnel plot. Results A total of 18 four-fold tables from 16 studies were analysed. The overall pooled sensitivity and specificity of PCR was 94% and 72%, respectively. The positive likelihood ratio (RLR) and negative likelihood ratio (NLR) was 2.73 and 0.12, respectively. The result of the diagnostic odds ratio (DOR) was 22.85 and the area under the curve (AUC) was 0.7884. Conclusion Establishing a laboratory diagnostic tool for L. pneumophila detection is important for epidemiological studies. In this work, PCR demonstrated a promising diagnostic accuracy for L. pneumophila. Supplementary Information The online version contains supplementary material available at 10.1186/s12941-022-00503-9.
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Affiliation(s)
- Xin Yin
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.,Department of Pediatrics, The Pediatrics School of Guangzhou Medical University, Guangzhou, 510182, China
| | - Ying-Zhou Chen
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.,Department of Clinical Medicine, The First Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Qi-Qing Ye
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.,Department of Pediatrics, The Pediatrics School of Guangzhou Medical University, Guangzhou, 510182, China
| | - Li-Juan Liao
- Department of Clinical Medicine, The First Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Zhuo-Rui Cai
- Department of Preventive Medicine, The School of Public Health of Guangzhou Medical University, Guangzhou, 511436, China
| | - Min Lin
- Department of Traditional Chinese and Western Medicine in Clinical Medicine, The Clinical School of Traditional Chinese and Western Medicine of Guangzhou Medical University, Guangzhou, 511436, China
| | - Jia-Na Li
- Department of Medical Imaging, The Second Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Geng-Biao Zhang
- Department of Medical Imaging, The Second Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Xiao-Li Peng
- Department of Traditional Chinese and Western Medicine in Clinical Medicine, The Clinical School of Traditional Chinese and Western Medicine of Guangzhou Medical University, Guangzhou, 511436, China
| | - Wen-Fang Shi
- Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Xu-Guang Guo
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China. .,Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, 511436, China. .,Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China. .,Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.
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3
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Bavari S, Mirkalantari S, Masjedian Jazi F, Darban-Sarokhalil D, Golnari Marani B. Risk assessment and quantitative measurement along with monitoring of Legionella in hospital water sources. New Microbes New Infect 2022; 45:100948. [PMID: 35399198 PMCID: PMC8984627 DOI: 10.1016/j.nmni.2021.100948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/21/2021] [Accepted: 12/20/2021] [Indexed: 11/25/2022] Open
Abstract
Legionella spp. as a causative agent of Legionnaires' disease (LD) and an opportunistic pathogen creates a public health problem. Isolation and quantification of this bacteria from clinic water sources are essential for hazard appraisal and sickness avoidance. This study aimed at risk assessment and quantitative measurement along with Legionella monitoring in educational hospital water sources in Tehran, Iran. A cross-sectional study was carried out in 1 year. The conventional culture method was used in this study to isolate Legionella from water samples. The polymerase chain reaction (PCR) technique was used to confirm the identity of the isolates and ensure that they were all Legionella. Quantitative PCR (qPCR) was used to determine the count of bacteria, and HeLa cell culture was used to determine the invasion of isolates. A total of 100 water samples were collected and inoculated on GVPC (glycine, vancomycin, polymyxin, and cycloheximide) agar; 12 (12%) and 42 (42%) cases were culture and PCR positive, respectively. Percentage of Legionella presence in PCR-positive samples by the qPCR method in <103 GU/L, in about 103 and lower than 104 GU/L, and in 104 GU/L was 40.47 (17 cases), 4.76% (two cases), and 54.76% (23 cases), respectively. Invasion analysis revealed that five and four isolates had invaded HeLa cells more than twice and equally, respectively, and the others had a lower invasion than the reference strain. The findings revealed that the spread of LD in hospitals was linked to the water system. Given the importance of nosocomial infections in the medical community, establishing a hospital water monitoring system is the most effective way to control these infections, particularly Legionella infections.
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4
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Linke RB, Zeki S, Mayer R, Keiblinger K, Savio D, Kirschner AKT, Reischer GH, Mach RL, Sommer R, Farnleitner AH. Identifying Inorganic Turbidity in Water Samples as Potential Loss Factor During Nucleic Acid Extraction: Implications for Molecular Fecal Pollution Diagnostics and Source Tracking. Front Microbiol 2021; 12:660566. [PMID: 34745021 PMCID: PMC8565874 DOI: 10.3389/fmicb.2021.660566] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
Molecular diagnostic methods are increasingly applied for food and environmental analysis. Since several steps are involved in sample processing which can affect the outcome (e.g., adhesion of DNA to the sample matrix, inefficient precipitation of DNA, pipetting errors and (partial) loss of the DNA pellet during DNA isolation), quality control is essential at all processing levels. In soil microbiology, particular attention has been paid to the inorganic component of the sample matrix affecting DNA extractability. In water quality testing, however, this aspect has mostly been neglected so far, although it is conceivable that these mechanisms have a similar impact. The present study was therefore dedicated to investigate possible matrix effects on results of water quality analysis. Field testing in an aquatic environment with pronounced chemo-physical gradients [total suspended solids (TSS), inorganic turbidity, total organic carbon (TOC), and conductivity] indicated a negative association between DNA extractability (using a standard phenol/chloroform extraction procedure) and turbidity (spearman ρ = −0.72, p < 0.001, n = 21). Further detailed laboratory experiments on sediment suspensions confirmed the hypothesis of inorganic turbidity being the main driver for reduced DNA extractability. The observed effects, as known from soil samples, were also indicated to result from competitive effects for free charges on clay minerals, leading to adsorption of DNA to these inorganic particles. A protocol modification by supplementing the extraction buffer with salmon sperm DNA, to coat charged surfaces prior to cell lysis, was then applied on environmental water samples and compared to the standard protocol. At sites characterized by high inorganic turbidity, DNA extractability was significantly improved or made possible in the first place by applying the adapted protocol. This became apparent from intestinal enterococci and microbial source tracking (MST)-marker levels measured by quantitative polymerase chain reaction (qPCR) (100 to 10,000-fold median increase in target concentrations). The present study emphasizes the need to consider inorganic turbidity as a potential loss factor in DNA extraction from water-matrices. Negligence of these effects can lead to a massive bias, by up to several orders of magnitude, in the results of molecular MST and fecal pollution diagnostics.
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Affiliation(s)
- Rita B Linke
- Research Group Environmental Microbiology and Molecular Diagnostics 166/5/3, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Sibel Zeki
- Department of Marine Environment, Institute of Marine Sciences and Management, Istanbul University, Istanbul, Turkey
| | - René Mayer
- Research Group Environmental Microbiology and Molecular Diagnostics 166/5/3, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Katharina Keiblinger
- Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences Vienna, Vienna, Austria
| | - Domenico Savio
- Research Group Environmental Microbiology and Molecular Diagnostics 166/5/3, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria.,Division Water Quality and Health, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
| | - Alexander K T Kirschner
- Division Water Quality and Health, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria.,Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | - Georg H Reischer
- Research Group Environmental Microbiology and Molecular Diagnostics 166/5/3, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria.,Research Area Molecular Diagnostics, Department IFA-Tulln, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Tulln, Austria
| | - Robert L Mach
- Research Division Biochemical Technology, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Regina Sommer
- Unit of Water Microbiology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | - Andreas H Farnleitner
- Research Group Environmental Microbiology and Molecular Diagnostics 166/5/3, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria.,Division Water Quality and Health, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
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5
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Donohue MJ. Quantification of Legionella pneumophila by qPCR and culture in tap water with different concentrations of residual disinfectants and heterotrophic bacteria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 774:145142. [PMID: 33610980 PMCID: PMC8358786 DOI: 10.1016/j.scitotenv.2021.145142] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 05/21/2023]
Abstract
Legionellosis prevalence is increasing in the United States. This disease is caused primarily by the bacterium Legionella pneumophila found in water and transmitted by aerosol inhalation. This pathogen has a slow growth rate and can "hide" in amoeba, making it difficult to monitor by the traditional culture method on selective media. Tap water samples (n = 358) collected across the United States were tested for L. pneumophila by both culture and quantitative Polymerase Chain Reaction (qPCR). The presence of other bacteria was quantified by heterotrophic plate counts (HPC). Residual disinfectant concentrations (free chlorine or monochloramine) were measured in all samples. Legionella pneumophila had the highest prevalence and concentration in the chlorinated water samples that had a free‑chlorine value of less than 0.2 mg Cl2/L. In total, 24% (87/358) of the samples were positive for L. pneumophila either by qPCR or 3% (11/358) were positive by culture. In chloramine-treated samples, L. pneumophila was detected by qPCR in 21% (31/148) and 1% (2/148) by culture, despite a high monochloramine residual >1 mg Cl2/L. Despite the presence of a high disinfectant residual (>1 mg Cl2/L), HPC counts were substantial. This study indicates that both culture and qPCR methods have limitations when predicting a potential risk for disease associated with L. pneumophila in tap water. Measuring disinfectant residuals and quantifying HPC in water samples may be useful adjunct parameters for reducing Legionellosis' risk from public water supplies at high-risk locations.
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Affiliation(s)
- Maura J Donohue
- United States Environmental Protection Agency, Office Research and Development, Center for Environmental Solutions and Emergency Response, Cincinnati, OH 45268, United States of America.
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6
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Ribes S, Ruiz-Rico M, Moreno-Mesonero L, Moreno Y, Barat JM. Natural antimicrobial compounds immobilised on silica microparticles as filtering materials: Impact on the metabolic activity and bacterial viability of waterborne microorganisms. ENVIRONMENTAL TECHNOLOGY & INNOVATION 2021; 21:101219. [DOI: 10.1016/j.eti.2020.101219] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
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7
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Hamilton KA, Hamilton MT, Johnson W, Jjemba P, Bukhari Z, LeChevallier M, Haas CN, Gurian PL. Risk-Based Critical Concentrations of Legionella pneumophila for Indoor Residential Water Uses. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:4528-4541. [PMID: 30629886 DOI: 10.1021/acs.est.8b03000] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Legionella spp. is a key contributor to the United States waterborne disease burden. Despite potentially widespread exposure, human disease is relatively uncommon, except under circumstances where pathogen concentrations are high, host immunity is low, or exposure to small-diameter aerosols occurs. Water quality guidance values for Legionella are available for building managers but are generally not based on technical criteria. To address this gap, a quantitative microbial risk assessment (QMRA) was conducted using target risk values in order to calculate corresponding critical concentrations on a per-fixture and aggregate (multiple fixture exposure) basis. Showers were the driving indoor exposure risk compared to sinks and toilets. Critical concentrations depended on the dose response model (infection vs clinical severity infection, CSI), risk target used (infection risk vs disability adjusted life years [DALY] on a per-exposure or annual basis), and fixture type (conventional vs water efficient or "green"). Median critical concentrations based on exposure to a combination of toilet, faucet, and shower aerosols ranged from ∼10-2 to ∼100 CFU per L and ∼101 to ∼103 CFU per L for infection and CSI dose response models, respectively. As infection model results for critical L. pneumophila concentrations were often below a feasible detection limit for culture-based assays, the use of CSI model results for nonhealthcare water systems with a 10-6 DALY pppy target (the more conservative target) would result in an estimate of 12.3 CFU per L (arithmetic mean of samples across multiple fixtures and/or over time). Single sample critical concentrations with a per-exposure-corrected DALY target at each conventional fixture would be 1.06 × 103 CFU per L (faucets), 8.84 × 103 CFU per L (toilets), and 14.4 CFU per L (showers). Using a 10-4 annual infection risk target would give a 1.20 × 103 CFU per L mean for multiple fixtures and single sample critical concentrations of 1.02 × 105, 8.59 × 105, and 1.40 × 103 CFU per L for faucets, toilets, and showers, respectively. Annual infection risk-based target estimates are in line with most current guidance documents of less than 1000 CFU per L, while DALY-based guidance suggests lower critical concentrations might be warranted in some cases. Furthermore, approximately <10 CFU per mL L. pneumophila may be appropriate for healthcare or susceptible population settings. This analysis underscores the importance of the choice of risk target as well as sampling program considerations when choosing the most appropriate critical concentration for use in public health guidance.
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Affiliation(s)
- Kerry A Hamilton
- School for Sustainable Engineering and the Built Environment , Arizona State University , Tempe , Arizona 85281 , United States
- The Biodesign Institute Center for Environmental Health Engineering , Arizona State University , Tempe , Arizona 85281 , United States
| | - Mark T Hamilton
- Microsoft Applied Artificial Intelligence Group , 1 Memorial Drive , Cambridge , Massachusetts 02142 , United States
| | - William Johnson
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Patrick Jjemba
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Zia Bukhari
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Mark LeChevallier
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Charles N Haas
- Drexel University , 3141 Chestnut Street , Philadelphia , Pennsylvania 19104 , United States
| | - P L Gurian
- Drexel University , 3141 Chestnut Street , Philadelphia , Pennsylvania 19104 , United States
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8
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Caicedo C, Rosenwinkel KH, Exner M, Verstraete W, Suchenwirth R, Hartemann P, Nogueira R. Legionella occurrence in municipal and industrial wastewater treatment plants and risks of reclaimed wastewater reuse: Review. WATER RESEARCH 2019; 149:21-34. [PMID: 30445393 DOI: 10.1016/j.watres.2018.10.080] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 05/22/2023]
Abstract
Wastewater treatment plants (WWTPs) have been identified as confirmed but until today underestimated sources of Legionella, playing an important role in local and community cases and outbreaks of Legionnaires' disease. In general, aerobic biological systems provide an optimum environment for the growth of Legionella due to high organic nitrogen and oxygen concentrations, ideal temperatures and the presence of protozoa. However, few studies have investigated the occurrence of Legionella in WWTPs, and many questions in regards to the interacting factors that promote the proliferation and persistence of Legionella in these treatment systems are still unanswered. This critical review summarizes the current knowledge about Legionella in municipal and industrial WWTPs, the conditions that might support their growth, as well as control strategies that have been applied. Furthermore, an overview of current quantification methods, guidelines and health risks associated with Legionella in reclaimed wastewater is also discussed in depth. A better understanding of the conditions promoting the occurrence of Legionella in WWTPs will contribute to the development of improved wastewater treatment technologies and/or innovative mitigation approaches to minimize future Legionella outbreaks.
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Affiliation(s)
- C Caicedo
- Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Hannover, 30167, Germany.
| | - K-H Rosenwinkel
- Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Hannover, 30167, Germany
| | - M Exner
- University of Bonn, Institute for Hygiene and Public Health, Bonn, Germany
| | - W Verstraete
- Ghent University, CMET, Ghent, and Avecom, Wondelgem, Belgium
| | - R Suchenwirth
- Public Health Office of Lower Saxony, Hannover, Germany
| | - P Hartemann
- Faculty of Medicine, Department of Environment and Public Health, Nancy University-CHU Nancy, Vandoeuvre Les Nancy, France
| | - R Nogueira
- Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Hannover, 30167, Germany.
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9
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Optimization of viability qPCR for selective detection of membrane-intact Legionella pneumophila. J Microbiol Methods 2018; 156:68-76. [PMID: 30529241 DOI: 10.1016/j.mimet.2018.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/04/2018] [Accepted: 12/04/2018] [Indexed: 11/23/2022]
Abstract
Although a number of viability qPCR assays have been reported to selectively detect signals from membrane-intact Legionella pneumophila, the efficient suppression of amplification of DNA from dead membrane-compromised bacteria remains an ongoing challenge. This research aimed at establishing a new oligonucleotide combination that allows for a better exclusion of dead Legionella pneumophila on basis of the mip gene. Propidium monoazide (PMA) was chosen as viability dye. An oligonucleotide combination for the amplification of a 633 bp sequence was established with 100% specificity for different Legionella pneumophila strains compared with 17 other Legionella species tested. Apart from increasing amplicon length, the study aimed at optimizing dye incubation time and temperature. An incubation temperature of 45 °C for 10 min was found optimal. Dye treatment of heat-killed bacteria in the presence of EDTA improved signal suppression, whereas deoxycholate also affected signals from live intact bacteria. Suppression of signals from heat-treated bacteria was found to be approx. twice as efficient compared to a commercial kit, although the detection sensitivity is superior when targeting short amplicons. With a limit of detection of 10 genome copies per PCR well and a 6-log signal reduction of bacteria killed at 80 °C, the assay appears useful for applications where pathogen numbers are not limiting and where the priority is on the distinction between intact and damaged Legionella pneumophila for the evaluation of hygienic risk and of disinfection efficiency.
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10
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Zhang Q, Ishii S. Improved simultaneous quantification of multiple waterborne pathogens and fecal indicator bacteria with the use of a sample process control. WATER RESEARCH 2018; 137:193-200. [PMID: 29550722 DOI: 10.1016/j.watres.2018.03.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/26/2018] [Accepted: 03/09/2018] [Indexed: 05/23/2023]
Abstract
Quantitative polymerase chain reaction (qPCR) is now commonly used to detect fecal indicator bacteria (FIB) as well as pathogens in water samples. However, DNA loss during sample processing can cause underestimation of target genes. In this study, we created a sample process control strain (SPC) by genetically engineering a non-pathogenic, Gram-negative bacterium Pseudogulbenkiania sp. strain NH8B. The SPC strain, named NH8B-1D2, has a kanamycin-resistance gene inserted to one of the 23S rRNA genes. To specifically quantify the SPC strain, a new TaqMan qPCR assay was developed. To obtain the relationship between the DNA recovery efficiencies of various pathogens and those of the SPC strain, known amount of E. coli O157:H7, Salmonella Typhimurium, Campylobacter jejuni, or Listeria monocytogenes cells were co-spiked with the SPC strain to environmental water samples. The DNA recovery efficiencies were calculated by comparing the quantity of bacterial cells inoculated to water samples prior to filtration and DNA extraction, and those measured by qPCR. We then obtained the ratios in the recovery efficiencies between pathogens and SPC strain (RRPATH/SPC). The RRPATH/SPC values obtained using Oono pond water collected in Japan were used as a pathogen-specific constant to estimate the accurate concentrations of pathogens in water samples collected from Mississippi River in Minnesota. Estimated pathogen concentrations were not significantly different from the inoculated pathogen concentration, suggesting our normalization approach is useful to estimate the accurate concentrations of pathogens in environmental water samples. The qPCR assay targeting the SPC strains and FIB were incorporated into the microfluidic qPCR chip format (PBQ chip ver. 2); therefore, we can simultaneously quantify multiple pathogens, FIB, and the SPC strain in high throughput from many water samples. This new tool can be useful for water quality monitoring and risk assessment.
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Affiliation(s)
- Qian Zhang
- BioTechnology Institute, University of Minnesota, St. Paul, MN, United States
| | - Satoshi Ishii
- BioTechnology Institute, University of Minnesota, St. Paul, MN, United States; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN, United States; Division of Environmental Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.
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11
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Samhan FA, Stedtfeld TM, Waseem H, Williams MR, Stedtfeld RD, Hashsham SA. On-filter direct amplification of Legionella pneumophila for rapid assessment of its abundance and viability. WATER RESEARCH 2017; 121:162-170. [PMID: 28527390 PMCID: PMC5525548 DOI: 10.1016/j.watres.2017.05.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/08/2017] [Accepted: 05/12/2017] [Indexed: 05/14/2023]
Abstract
Guidelines and regulations to control Legionella pneumophila in cooling water systems of large buildings are evolving due to the increasing number of outbreaks. Rapid, on-site, simple, and sensitive quantification methods that are also able to assess viability may be extremely useful in monitoring and control. Culture-based methods for measuring L. pneumophila may take 4-10 days and qPCR-based methods are also slow, requiring at least a day from sample to result, albeit mainly due to the need for sample transport to a centralized laboratory. This study reports a rapid isothermal amplification method for L. pneumophila concentration and detection with live/dead differentiation under field conditions. Using an on-filter direct amplification (i.e., amplification of cells without DNA extraction and purification) approach with propidium monoazide (PMA), and a real time isothermal amplification platform (Gene-Z), L. pneumophila could be detected in 1-2 h at ∼1 cfu/100 ml of tap water. Signature sequences from 16S rRNA and cadA genes were used as genetic markers for L. pneumophila and loop-mediated isothermal amplification (LAMP) primers were designed using Primer Explorer V4. Result were also compared with direct amplification of cells spiked into distilled, tap, and cooling water samples as well as extracted DNA by qPCR. This method may be useful to managers of cooling water systems in large buildings for rapid detection of L. pneumophila. The overall approach of on-site sample concentration, on-filter amplification, and live/dead differentiation may be extended to other organisms where analytical sensitivity and speed are equally important.
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Affiliation(s)
- Farag A Samhan
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Tiffany M Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Hassan Waseem
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Maggie R Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Robert D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA; Center for Microbial Ecology, Michigan State University, East Lansing, MI, USA.
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12
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Wang H, Bédard E, Prévost M, Camper AK, Hill VR, Pruden A. Methodological approaches for monitoring opportunistic pathogens in premise plumbing: A review. WATER RESEARCH 2017; 117:68-86. [PMID: 28390237 PMCID: PMC5693313 DOI: 10.1016/j.watres.2017.03.046] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/19/2017] [Accepted: 03/22/2017] [Indexed: 05/06/2023]
Abstract
Opportunistic premise (i.e., building) plumbing pathogens (OPPPs, e.g., Legionella pneumophila, Mycobacterium avium complex, Pseudomonas aeruginosa, Acanthamoeba, and Naegleria fowleri) are a significant and growing source of disease. Because OPPPs establish and grow as part of the native drinking water microbiota, they do not correspond to fecal indicators, presenting a major challenge to standard drinking water monitoring practices. Further, different OPPPs present distinct requirements for sampling, preservation, and analysis, creating an impediment to their parallel detection. The aim of this critical review is to evaluate the state of the science of monitoring OPPPs and identify a path forward for their parallel detection and quantification in a manner commensurate with the need for reliable data that is informative to risk assessment and mitigation. Water and biofilm sampling procedures, as well as factors influencing sample representativeness and detection sensitivity, are critically evaluated with respect to the five representative bacterial and amoebal OPPPs noted above. Available culturing and molecular approaches are discussed in terms of their advantages, limitations, and applicability. Knowledge gaps and research needs towards standardized approaches are identified.
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Affiliation(s)
- Hong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
| | - Emilie Bédard
- Department of Civil Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Anne K Camper
- Center for Biofilm Engineering and Department of Civil Engineering, Montana State University, Bozeman, MT 59717, USA
| | - Vincent R Hill
- Waterborne Disease Prevention Branch, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30329, USA
| | - Amy Pruden
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061, USA
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An Optimized Method for Quantification of Pathogenic Leptospira in Environmental Water Samples. PLoS One 2016; 11:e0160523. [PMID: 27487084 PMCID: PMC4972417 DOI: 10.1371/journal.pone.0160523] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/20/2016] [Indexed: 12/19/2022] Open
Abstract
Leptospirosis is a zoonotic disease usually acquired by contact with water contaminated with urine of infected animals. However, few molecular methods have been used to monitor or quantify pathogenic Leptospira in environmental water samples. Here we optimized a DNA extraction method for the quantification of leptospires using a previously described Taqman-based qPCR method targeting lipL32, a gene unique to and highly conserved in pathogenic Leptospira. QIAamp DNA mini, MO BIO PowerWater DNA and PowerSoil DNA Isolation kits were evaluated to extract DNA from sewage, pond, river and ultrapure water samples spiked with leptospires. Performance of each kit varied with sample type. Sample processing methods were further evaluated and optimized using the PowerSoil DNA kit due to its performance on turbid water samples and reproducibility. Centrifugation speeds, water volumes and use of Escherichia coli as a carrier were compared to improve DNA recovery. All matrices showed a strong linearity in a range of concentrations from 106 to 10° leptospires/mL and lower limits of detection ranging from <1 cell /ml for river water to 36 cells/mL for ultrapure water with E. coli as a carrier. In conclusion, we optimized a method to quantify pathogenic Leptospira in environmental waters (river, pond and sewage) which consists of the concentration of 40 mL samples by centrifugation at 15,000×g for 20 minutes at 4°C, followed by DNA extraction with the PowerSoil DNA Isolation kit. Although the method described herein needs to be validated in environmental studies, it potentially provides the opportunity for effective, timely and sensitive assessment of environmental leptospiral burden.
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14
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Botelho-Nevers E, Grattard F, Viallon A, Allegra S, Jarraud S, Verhoeven P, Marcuccilli A, Lucht F, Pozzetto B, Berthelot P. Prospective evaluation of RT-PCR on sputum versus culture, urinary antigens and serology for Legionnaire's disease diagnosis. J Infect 2016; 73:123-8. [PMID: 27306488 DOI: 10.1016/j.jinf.2016.04.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/27/2016] [Accepted: 04/19/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVES Legionnaires' disease (LD) is a severe disease associated with community and hospital-acquired pneumonia, frequently under diagnosed. The main aim of our study was to determine the value of PCR for the diagnosis of LD in routine clinical practice. METHODS In a prospective study, from March 2007 to April 2010, the value of PCR on non-invasive respiratory specimens (NIRS) was compared to those of the other available tools for LD diagnosis in patients hospitalized for pneumonia. RESULTS Among 254 consecutive cases of pneumonia included, 24 cases were LD (19 confirmed and 5 probable) representing the first documented microbiological etiology. Molecular diagnosis of LD was performed on NIRS by using 16S rRNA PCR, and secondarily mip PCR, with no discrepant results between the 2 methods: it was found positive in 14 cases and led to identify 2 supplementary probable cases of LD. Based on clinical and at least 2 positive LD tests, PCR yielded a better diagnostic value than antigen urinary test (12 vs 10 cases). CONCLUSION These results revealed that molecular diagnosis of LD on NIRS is reliable and may contribute to better identify cases of LD.
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Affiliation(s)
- Elisabeth Botelho-Nevers
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France; Infectious Diseases Department, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Florence Grattard
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France; Laboratory of Infectious Agents and Hygiene, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Alain Viallon
- Emergency Unit, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Séverine Allegra
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France
| | - Sophie Jarraud
- Reference National Centre for Legionella, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France
| | - Paul Verhoeven
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France; Laboratory of Infectious Agents and Hygiene, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Adrien Marcuccilli
- Emergency Unit, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Fréderic Lucht
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France; Infectious Diseases Department, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Bruno Pozzetto
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France; Laboratory of Infectious Agents and Hygiene, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France
| | - Philippe Berthelot
- GIMAP EA 3064 (Groupe Immunité des Muqueuses et Agents Pathogènes), COMUE of Lyon, 42023 Saint-Etienne, France; Infectious Diseases Department, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France; Laboratory of Infectious Agents and Hygiene, University Hospital of Saint-Etienne, 42055 Saint-Etienne Cedex 02, France.
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15
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Reyneke B, Dobrowsky PH, Ndlovu T, Khan S, Khan W. EMA-qPCR to monitor the efficiency of a closed-coupled solar pasteurization system in reducing Legionella contamination of roof-harvested rainwater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 553:662-670. [PMID: 26990076 DOI: 10.1016/j.scitotenv.2016.02.108] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 02/12/2016] [Accepted: 02/15/2016] [Indexed: 06/05/2023]
Abstract
Solar pasteurization is effective in reducing the level of indicator organisms in stored rainwater to within drinking water standards. However, Legionella spp. were detected at temperatures exceeding the recommended pasteurization temperatures using polymerase chain reaction assays. The aim of the current study was thus to apply EMA quantitative polymerase chain reaction (EMA-qPCR) to determine whether the Legionella spp. detected were intact cells and therefore possibly viable at pasteurization temperatures >70°C. The BacTiter-Glo™ Microbial Cell Viability Assay was also used to detect the presence of ATP in the tested samples, as ATP indicates the presence of metabolically active cells. Chemical analysis also indicated that all anions and cations were within the respective drinking water guidelines, with the exception of iron (mean: 186.76 μg/L) and aluminium (mean: 188.13 μg/L), which were detected in the pasteurized tank water samples at levels exceeding recommended guidelines. The BacTiter-Glo™ Microbial Cell Viability Assay indicated the presence of viable cells for all pasteurized temperatures tested, with the percentage of ATP (in the form of relative light units) decreasing with increasing temperature [70-79°C (96.7%); 80- 89°C (99.2%); 90-95°C (99.7%)]. EMA-qPCR then indicated that while solar pasteurization significantly reduced (p<0.05) the genomic copy numbers of intact Legionella cells in the pasteurized tank water (~99%), no significant difference (p>0.05) in the mean copy numbers was detected with an increase in the pasteurization temperature, with 6 × 10(3) genomic copies/mL DNA sample obtained at 95°C. As intact Legionella cells were detected in the pasteurized tank water samples, quantitative microbial risk assessment studies need to be conducted to determine the potential health risk associated with using the water for domestic purposes.
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Affiliation(s)
- B Reyneke
- Department of Microbiology, Faculty of Science, University of Stellenbosch, Private Bag X1, Stellenbosch 7602, South Africa
| | - P H Dobrowsky
- Department of Microbiology, Faculty of Science, University of Stellenbosch, Private Bag X1, Stellenbosch 7602, South Africa
| | - T Ndlovu
- Department of Microbiology, Faculty of Science, University of Stellenbosch, Private Bag X1, Stellenbosch 7602, South Africa
| | - S Khan
- Department of Biomedical Sciences, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, P.O. Box 1906, Bellville 7535, South Africa
| | - W Khan
- Department of Microbiology, Faculty of Science, University of Stellenbosch, Private Bag X1, Stellenbosch 7602, South Africa.
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16
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Kusić D, Rösch P, Popp J. Fast label-free detection of Legionella spp. in biofilms by applying immunomagnetic beads and Raman spectroscopy. Syst Appl Microbiol 2016; 39:132-40. [DOI: 10.1016/j.syapm.2016.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/18/2016] [Accepted: 01/21/2016] [Indexed: 11/29/2022]
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17
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Janczarek M, Palusińska-Szysz M. PCR method for the rapid detection and discrimination of Legionella spp. based on the amplification of pcs, pmtA, and 16S rRNA genes. J Appl Genet 2015; 57:251-61. [PMID: 26423783 DOI: 10.1007/s13353-015-0317-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/18/2015] [Accepted: 09/14/2015] [Indexed: 10/23/2022]
Abstract
Legionella bacteria are organisms of public health interest due to their ability to cause pneumonia (Legionnaires' disease) in susceptible humans and their ubiquitous presence in water supply systems. Rapid diagnosis of Legionnaires' disease allows the use of therapy specific for the disease. L. pneumophila serogroup 1 is the most common cause of infection acquired in community and hospital environments. The non-L. pneumophila infections are likely under-detected because of a lack of effective diagnosis. In this work, simplex and duplex PCR assays with the use of new molecular markers pcs and pmtA involved in phosphatidylcholine synthesis were specified for rapid and cost-efficient identification and distinguishing Legionella species. The sets of primers developed were found to be sensitive and specific for reliable detection of Legionella belonging to the eight most clinically relevant species. Among these, four primer sets I, II, VI, and VII used for duplex-PCRs proved to have the highest identification power and reliability in the detection of the bacteria. Application of this PCR-based method should improve detection of Legionella spp. in both clinical and environmental settings and facilitate molecular typing of these organisms.
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Affiliation(s)
- Monika Janczarek
- Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Sklodowska University, Akademicka St. 19, 20-033, Lublin, Poland
| | - Marta Palusińska-Szysz
- Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Sklodowska University, Akademicka St. 19, 20-033, Lublin, Poland.
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18
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Ditommaso S, Giacomuzzi M, Ricciardi E, Zotti CM. Viability-qPCR for detecting Legionella: Comparison of two assays based on different amplicon lengths. Mol Cell Probes 2015; 29:237-43. [DOI: 10.1016/j.mcp.2015.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 05/20/2015] [Accepted: 05/22/2015] [Indexed: 11/24/2022]
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19
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Shen SM, Chou MY, Hsu BM, Ji WT, Hsu TK, Tsai HF, Huang YL, Chiu YC, Kao ES, Kao PM, Fan CW. Assessment of Legionella pneumophila in recreational spring water with quantitative PCR (Taqman) assay. Pathog Glob Health 2015; 109:236-41. [PMID: 26184706 DOI: 10.1179/2047773215y.0000000023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Legionella spp. are common in various natural and man-made aquatic environments. Recreational hot spring is frequently reported as an infection hotspot because of various factors such as temperature and humidity. Although polymerase chain reaction (PCR) had been used for detecting Legionella, several inhibitors such as humic substances, calcium, and melanin in the recreational spring water may interfere with the reaction thus resulting in risk underestimation. The purpose of this study was to compare the efficiencies of conventional and Taqman quantitative PCR (qPCR) on detecting Legionella pneumophila in spring facilities and in receiving water. In the results, Taqman PCR had much better efficiency on specifying the pathogen in both river and spring samples. L. pneumophila was detected in all of the 27 river water samples and 45 of the 48 hot spring water samples. The estimated L. pneumophela concentrations ranged between 1.0 × 10(2) and 3.3 × 10(5) cells/l in river water and 72.1-5.7 × 10(6) cells/l in hot spring water. Total coliforms and turbidity were significantly correlated with concentrations of L. pneumophila in positive water samples. Significant difference was also found in water temperature between the presence/absence of L. pneumophila. Our results suggest that conventional PCR may be not enough for detecting L. pneumophila particularly in the aquatic environments full of reaction inhibitors.
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20
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Omiccioli E, Schiavano GF, Ceppetelli V, Amagliani G, Magnani M, Brandi G. Validation according to ISO/TS 12869:2012 of a molecular method for the isolation and quantification of Legionella spp. in water. Mol Cell Probes 2015; 29:86-91. [DOI: 10.1016/j.mcp.2014.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 12/19/2014] [Accepted: 12/19/2014] [Indexed: 10/24/2022]
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21
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Baudart J, Guillaume C, Mercier A, Lebaron P, Binet M. Rapid quantification of viable Legionella
in nuclear cooling tower waters using filter cultivation, fluorescent in situ
hybridization and solid-phase cytometry. J Appl Microbiol 2015; 118:1238-49. [DOI: 10.1111/jam.12783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/12/2015] [Accepted: 02/12/2015] [Indexed: 11/29/2022]
Affiliation(s)
- J. Baudart
- Sorbonne Universités; UPMC Univ Paris 06; USR 3579; LBBM; Observatoire Océanologique; Banyuls/mer France
- CNRS; USR 3579; LBBM; Observatoire Océanologique; Banyuls/mer France
| | - C. Guillaume
- EDF; Laboratoire National d'Hydraulique et Environnement; Chatou France
- Euro Engineering; Énergie-Environnement; Puteaux France
| | - A. Mercier
- Sorbonne Universités; UPMC Univ Paris 06; USR 3579; LBBM; Observatoire Océanologique; Banyuls/mer France
- CNRS; USR 3579; LBBM; Observatoire Océanologique; Banyuls/mer France
| | - P. Lebaron
- Sorbonne Universités; UPMC Univ Paris 06; USR 3579; LBBM; Observatoire Océanologique; Banyuls/mer France
- CNRS; USR 3579; LBBM; Observatoire Océanologique; Banyuls/mer France
| | - M. Binet
- EDF; Laboratoire National d'Hydraulique et Environnement; Chatou France
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22
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Antibody-modified iron oxide nanoparticles for efficient magnetic isolation and flow cytometric determination of L. pneumophila. Mikrochim Acta 2015. [DOI: 10.1007/s00604-015-1466-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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23
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Ditommaso S, Ricciardi E, Giacomuzzi M, Arauco Rivera SR, Zotti CM. Legionella in water samples: How can you interpret the results obtained by quantitative PCR? Mol Cell Probes 2015; 29:7-12. [DOI: 10.1016/j.mcp.2014.09.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 09/09/2014] [Accepted: 09/09/2014] [Indexed: 11/29/2022]
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24
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Ditommaso S, Ricciardi E, Giacomuzzi M, Arauco Rivera SR, Ceccarelli A, Zotti CM. Overestimation of the Legionella spp. load in environmental samples by quantitative real-time PCR: pretreatment with propidium monoazide as a tool for the assessment of an association between Legionella concentration and sanitary risk. Diagn Microbiol Infect Dis 2014; 80:260-6. [PMID: 25284373 DOI: 10.1016/j.diagmicrobio.2014.09.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 09/08/2014] [Accepted: 09/08/2014] [Indexed: 11/29/2022]
Abstract
Quantitative polymerase chain reaction (qPCR) offers rapid, sensitive, and specific detection of Legionella in environmental water samples. In this study, qPCR and qPCR combined with propidium monoazide (PMA-qPCR) were both applied to hot-water system samples and compared to traditional culture techniques. In addition, we evaluated the ability of PMA-qPCR to monitor the efficacy of different disinfection strategies. Comparison between the quantification obtained by culture and by qPCR or PMA-qPCR on environmental water samples confirms that the concentration of Legionella estimated by GU/L is generally higher than that estimated in CFU/L. Our results on 57 hot-water-system samples collected from 3 different sites show that: i) qPCR results were on average 178-fold higher than the culture results (Δ log10=2.25), ii) PMA-qPCR results were on average 27-fold higher than the culture results (Δ log10=1.43), iii) propidium monoazide-induced signal reduction in qPCR were nearly 10-fold (Δ log10=0.95), and that iv) different degrees of correlations between the 3 methods might be explained by different matrix properties, but also by different disinfection methods affecting cultivability of Legionella. In our study, we calculated the logarithmic differences between the results obtained by PMA-qPCR and those obtained by culture, and we suggested an algorithm for the interpretation of PMA-qPCR results for the routine monitoring of healthcare water systems using a commercial qPCR system (iQ-check real-time PCR kit; Bio-Rad, Marnes-la-Coquette, France).
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Affiliation(s)
- Savina Ditommaso
- Department of Public Health and Pediatrics, University of Turin, Italy.
| | - Elisa Ricciardi
- Department of Public Health and Pediatrics, University of Turin, Italy
| | - Monica Giacomuzzi
- Department of Public Health and Pediatrics, University of Turin, Italy
| | | | - Adriano Ceccarelli
- Department of Clinical and Biological Sciences, University of Turin, Italy
| | - Carla M Zotti
- Department of Public Health and Pediatrics, University of Turin, Italy
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25
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Taylor MJ, Bentham RH, Ross KE. Limitations of Using Propidium Monoazide with qPCR to Discriminate between Live and Dead Legionella in Biofilm Samples. Microbiol Insights 2014; 7:15-24. [PMID: 25288885 PMCID: PMC4167484 DOI: 10.4137/mbi.s17723] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 06/30/2014] [Accepted: 07/08/2014] [Indexed: 01/17/2023] Open
Abstract
Accurately quantifying Legionella for regulatory purposes to protect public health is essential. Real-time PCR (qPCR) has been proposed as a better method for detecting and enumerating Legionella in samples than conventional culture method. However, since qPCR amplifies any target DNA in the sample, the technique’s inability to discriminate between live and dead cells means that counts are generally significantly overestimated. Propidium monoazide (PMA) has been used successfully in qPCR to aid live/dead discrimination. We tested PMA use as a method to count only live Legionella cells in samples collected from a modified chemostat that generates environmentally comparable samples. Counts from PMA-treated samples that were pretreated with either heat or three types of disinfectants (to kill the cells) were highly variable, with the only consistent trend being the relationship between biofilm mass and numbers of Legionella cells. Two possibilities explain this result: 1. PMA treatment worked and the subsequent muted response of Legionella to disinfection treatment is a factor of biofilm/microbiological effects; although this does not account for the relationship between the amount of biofilm sampled and the viable Legionella count as determined by PMA-qPCR; or 2. PMA treatment did not work, and any measured decrease or increase in detectable Legionella is because of other factors affecting the method. This is the most likely explanation for our results, suggesting that higher concentrations of PMA might be needed to compensate for the presence of other compounds in an environmental sample or that lower amounts of biofilm need to be sampled. As PMA becomes increasingly toxic at higher concentrations and is very expensive, augmenting the method to include higher PMA concentrations is both counterproductive and cost prohibitive. Conversely, if smaller volumes of biofilm are used, the reproducibility of the method is reduced. Our results suggest that using PMA is not an appropriate method for discriminating between live and dead cells to enumerate Legionella for regulatory purposes.
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Affiliation(s)
- Michael J Taylor
- Health and Environment, School of the Environment, Flinders University, Adelaide, Australia
| | - Richard H Bentham
- Health and Environment, School of the Environment, Flinders University, Adelaide, Australia
| | - Kirstin E Ross
- Health and Environment, School of the Environment, Flinders University, Adelaide, Australia
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26
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Kao PM, Hsu BM, Hsu TK, Ji WT, Huang PH, Hsueh CJ, Chiang CS, Huang SW, Huang YL. Application of TaqMan fluorescent probe-based quantitative real-time PCR assay for the environmental survey of Legionella spp. and Legionella pneumophila in drinking water reservoirs in Taiwan. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 490:416-421. [PMID: 24867705 DOI: 10.1016/j.scitotenv.2014.04.103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/24/2014] [Accepted: 04/25/2014] [Indexed: 06/03/2023]
Abstract
In this study, TaqMan fluorescent quantitative real-time PCR was performed to quantify Legionella species in reservoirs. Water samples were collected from 19 main reservoirs in Taiwan, and 12 (63.2%) were found to contain Legionella spp. The identified species included uncultured Legionella spp., L. pneumophila, L. jordanis, and L. drancourtii. The concentrations of Legionella spp. and L. pneumophila in the water samples were in the range of 1.8×10(2)-2.6×10(3) and 1.6×10(2)-2.4×10(2) cells/L, respectively. The presence and absence of Legionella spp. in the reservoir differed significantly in pH values. These results highlight the importance that L. pneumophila, L. jordanis, and L. drancourtii are potential pathogens in the reservoirs. The presence of L. pneumophila in reservoirs may be a potential public health concern that must be further examined.
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Affiliation(s)
- Po-Min Kao
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi, Taiwan, ROC
| | - Bing-Mu Hsu
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi, Taiwan, ROC.
| | - Tsui-Kang Hsu
- Department of Ophthalmology, Cheng Hsin General Hospital, Taipei, Taiwan, ROC
| | - Wen-Tsai Ji
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi, Taiwan, ROC
| | - Po-Hsiang Huang
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi, Taiwan, ROC
| | - Chih-Jen Hsueh
- Department of Otorhinolaryngology, Cheng Hsin General Hospital, Taipei, Taiwan, ROC
| | - Chuen-Sheue Chiang
- Research and Diagnostic Center, Centers for Disease Control, Taiwan, ROC
| | - Shih-Wei Huang
- Center for General Education, Cheng-Shiu University, Kaohsiung, Taiwan, ROC
| | - Yu-Li Huang
- Department of Safety Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan, ROC
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27
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Donohue MJ, O'Connell K, Vesper SJ, Mistry JH, King D, Kostich M, Pfaller S. Widespread molecular detection of Legionella pneumophila Serogroup 1 in cold water taps across the United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:3145-3152. [PMID: 24548208 DOI: 10.1021/es4055115] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the United States, 6,868 cases of legionellosis were reported to the Center for Disease Control and Prevention in 2009-2010. Of these reports, it is estimated that 84% are caused by the microorganism Legionella pneumophila Serogroup (Sg) 1. Legionella spp. have been isolated and recovered from a variety of natural freshwater environments. Human exposure to L. pneumophila Sg1 may occur from aerosolization and subsequent inhalation of household and facility water. In this study, two primer/probe sets (one able to detect L. pneumophila and the other L. pneumophila Sg1) were determined to be highly sensitive and selective for their respective targets. Over 272 water samples, collected in 2009 and 2010 from 68 public and private water taps across the United States, were analyzed using the two qPCR assays to evaluate the incidence of L. pneumophila Sg1. Nearly half of the taps showed the presence of L. pneumophila Sg1 in one sampling event, and 16% of taps were positive in more than one sampling event. This study is the first United States survey to document the occurrence and colonization of L. pneumophila Sg1 in cold water delivered from point of use taps.
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Affiliation(s)
- Maura J Donohue
- Office of Research and Development, National Exposure Research Laboratory, United States Environmental Protection Agency , 26 West Martin Luther King Drive, Mail Stop 593, Cincinnati, Ohio 45268, United States
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28
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Abstract
Legionella spp. are the causative agent of Legionnaire's disease and an opportunistic pathogen of significant public health concern. Identification and quantification from environmental sources is crucial for identifying outbreak origins and providing sufficient information for risk assessment and disease prevention. Currently there are a range of methods for Legionella spp. quantification from environmental sources, but the two most widely used and accepted are culture and real-time polymerase chain reaction (qPCR). This paper provides a review of these two methods and outlines their advantages and limitations. Studies from the last 10 years which have concurrently used culture and qPCR to quantify Legionella spp. from environmental sources have been compiled. 26/28 studies detected Legionella at a higher rate using qPCR compared to culture, whilst only one study detected equivalent levels of Legionella spp. using both qPCR and culture. Aggregating the environmental samples from all 28 studies, 2856/3967 (72%) tested positive for the presence of Legionella spp. using qPCR and 1331/3967 (34%) using culture. The lack of correlation between methods highlights the need to develop an acceptable standardized method for quantification that is sufficient for risk assessment and management of this human pathogen.
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Affiliation(s)
- Harriet Whiley
- a Department of Health and the Environment , Flinders University , Adelaide , Australia
| | - Michael Taylor
- a Department of Health and the Environment , Flinders University , Adelaide , Australia
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Hatt JK, Ritalahti KM, Ogles DM, Lebrón CA, Löffler FE. Design and application of an internal amplification control to improve Dehalococcoides mccartyi 16S rRNA gene enumeration by qPCR. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:11131-8. [PMID: 24053159 DOI: 10.1021/es4019817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Dehalococcoides mccartyi (Dhc) strains are keystone bacteria for reductive dechlorination of chlorinated ethenes to nontoxic ethene in contaminated aquifers. Enumeration of Dhc biomarker genes using quantitative real-time PCR (qPCR) in groundwater is a key component of site assessment and bioremediation monitoring. Unfortunately, standardized qPCR procedures that recognize impaired measurements due to PCR inhibition, low template DNA concentrations, or analytical error are not available, thus limiting confidence in qPCR data. To improve contemporary approaches for enumerating Dhc in environmental samples, multiplex qPCR assays were designed to quantify the Dhc 16S rRNA gene and one of two different internal amplification controls (IACs): a modified Dhc 16S rRNA gene fragment (Dhc*) and the firefly luciferase gene luc. The Dhc* IAC exhibited competitive inhibition in qPCR with the Dhc 16S rRNA gene template when the ratio of either target was 100-fold greater than the other target. A multiplex qPCR assay with the luc IAC avoided competitive inhibition and accurately quantified Dhc abundances ranging from ∼10 to 10(7) 16S rRNA gene copies per reaction. The addition of ∼10(6) E. coli luc IAC to simulated groundwater amended with the Dhc-containing consortium KB-1 yielded reproducible luc counts after DNA extraction and multiplex qPCR enumeration. The application of the luc IAC assay improved Dhc biomarker gene quantification from simulated groundwater samples and is a valuable approach for "ground truthing" qPCR data obtained in different laboratories, thus reducing ambiguity associated with qPCR enumeration and reproducibility.
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Affiliation(s)
- Janet K Hatt
- School of Civil and Environmental Engineering, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332, United States
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Error estimation in environmental DNA targets quantification due to PCR efficiencies differences between real samples and standards. Folia Microbiol (Praha) 2013; 58:657-62. [DOI: 10.1007/s12223-013-0255-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 04/23/2013] [Indexed: 10/26/2022]
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Baume M, Garrelly L, Facon J, Bouton S, Fraisse P, Yardin C, Reyrolle M, Jarraud S. The characterization and certification of a quantitative reference material for Legionella
detection and quantification by qPCR. J Appl Microbiol 2013; 114:1725-33. [DOI: 10.1111/jam.12172] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/15/2013] [Accepted: 02/15/2013] [Indexed: 11/26/2022]
Affiliation(s)
- M. Baume
- Hospices Civils de Lyon; Centre National de Référence des Légionelles; Lyon France
| | | | - J.P. Facon
- Bio-Rad; R&D Department; Marnes-la-coquette; France
| | - S. Bouton
- PALL GeneDisc Technologies; 1 rue du Courtil centre d'affaires CICEA 35170; Bruz France
| | - P.O. Fraisse
- LNE; Direction de la Métrologie Scientifique et Industrielle; Paris France
| | - C. Yardin
- LNE; Direction de la Métrologie Scientifique et Industrielle; Paris France
| | - M. Reyrolle
- Hospices Civils de Lyon; Centre National de Référence des Légionelles; Lyon France
| | - S. Jarraud
- Hospices Civils de Lyon; Centre National de Référence des Légionelles; Lyon France
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32
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Knez K, Janssen KPF, Spasic D, Declerck P, Vanysacker L, Denis C, Tran DT, Lammertyn J. Spherical Nucleic Acid Enhanced FO-SPR DNA Melting for Detection of Mutations in Legionella pneumophila. Anal Chem 2013; 85:1734-42. [DOI: 10.1021/ac303008f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Karel Knez
- BIOSYST—MeBioS, KU Leuven—University of Leuven, Willem De Croylaan
42, P.O. Box 2428, B-3001 Leuven, Belgium
| | - Kris P. F. Janssen
- BIOSYST—MeBioS, KU Leuven—University of Leuven, Willem De Croylaan
42, P.O. Box 2428, B-3001 Leuven, Belgium
| | - Dragana Spasic
- BIOSYST—MeBioS, KU Leuven—University of Leuven, Willem De Croylaan
42, P.O. Box 2428, B-3001 Leuven, Belgium
| | - Priscilla Declerck
- Laboratorium for Aquatic Ecology
en Evolutionary Biology, KU Leuven—University of Leuven, Charles Deberiotstraat 32, P.O. Box 2439,
B-3000 Leuven, Belgium
| | - Louise Vanysacker
- Centre for Surface Chemistry
and Catalysis, KU Leuven—University of Leuven, Kasteelpark Arenberg 23, P.O. Box 2461, B-3001 Heverlee, Belgium
| | - Carla Denis
- Laboratorium for Aquatic Ecology
en Evolutionary Biology, KU Leuven—University of Leuven, Charles Deberiotstraat 32, P.O. Box 2439,
B-3000 Leuven, Belgium
| | - Dinh T. Tran
- Department of Food Processing,
Faculty of Food Science and Technology, Hanoi University of Agriculture, 10000 Hanoi, Vietnam
| | - Jeroen Lammertyn
- BIOSYST—MeBioS, KU Leuven—University of Leuven, Willem De Croylaan
42, P.O. Box 2428, B-3001 Leuven, Belgium
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Abstract
To avoid further cases arising from an infectious source it is essential to ensure the early identification of all potential source(s) within an identified area, or buildings, to determine if they are being managed safely; to take appropriate samples and ensure appropriate remedial actions are taken to remove the risk of further cases. If samples are to give representative results of the system at the time of sampling it is essential to ensure that they are processed appropriately using methods which are both sensitive and specific. It is also imperative that results are interpreted in context and transmitted as soon as possible to the outbreak control team to ensure appropriate and timely action is taken on sites which still pose a risk of infection. A multidisciplinary team approach and forward planning are essential to ensure that there are sufficiently trained and competent personnel and resources. Recognition of sources is dependent on many factors including thorough epidemiological investigations to narrow down the potential geographical area or water system that maybe common to the patients as agreed within the outbreak case definition. qPCR can be useful in both the elimination and identification of suspect systems/sites. However, it requires expert interpretation of results in the context of the sample site and factors which may affect the results such as the use of biocides together with the use of an algorithm for interpretation and actions to be taken to put the results in context.
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Botes M, de Kwaadsteniet M, Cloete TE. Application of quantitative PCR for the detection of microorganisms in water. Anal Bioanal Chem 2013; 405:91-108. [PMID: 23001336 PMCID: PMC7079929 DOI: 10.1007/s00216-012-6399-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 11/13/2022]
Abstract
The occurrence of microorganisms in water due to contamination is a health risk and control thereof is a necessity. Conventional detection methods may be misleading and do not provide rapid results allowing for immediate action. The quantitative polymerase chain reaction (qPCR) method has proven to be an effective tool to detect and quantify microorganisms in water within a few hours. Quantitative PCR assays have recently been developed for the detection of specific adeno- and polyomaviruses, bacteria and protozoa in different water sources. The technique is highly sensitive and able to detect low numbers of microorganisms. Quantitative PCR can be applied for microbial source tracking in water sources, to determine the efficiency of water and wastewater treatment plants and act as a tool for risk assessment. Different qPCR assays exist depending on whether an internal control is used or whether measurements are taken at the end of the PCR reaction (end-point qPCR) or in the exponential phase (real-time qPCR). Fluorescent probes are used in the PCR reaction to hybridise within the target sequence to generate a signal and, together with specialised systems, quantify the amount of PCR product. Quantitative reverse transcription polymerase chain reaction (q-RT-PCR) is a more sensitive technique that detects low copy number RNA and can be applied to detect, e.g. enteric viruses and viable microorganisms in water, and measure specific gene expression. There is, however, a need to standardise qPCR protocols if this technique is to be used as an analytical diagnostic tool for routine monitoring. This review focuses on the application of qPCR in the detection of microorganisms in water.
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Affiliation(s)
- Marelize Botes
- Department of Microbiology, University of Stellenbosch, Private Bag XI, Matieland 7602, Stellenbosch, Western Cape 7602, South Africa.
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A new molecular approach to help conclude drowning as a cause of death: Simultaneous detection of eight bacterioplankton species using real-time PCR assays with TaqMan probes. Forensic Sci Int 2012; 222:11-26. [DOI: 10.1016/j.forsciint.2012.04.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Accepted: 04/25/2012] [Indexed: 11/23/2022]
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Detection and Quantification of Legionella pneumophila from Water Systems in Kuwait Residential Facilities. J Pathog 2012; 2012:138389. [PMID: 22888441 PMCID: PMC3409524 DOI: 10.1155/2012/138389] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/27/2012] [Accepted: 05/30/2012] [Indexed: 11/22/2022] Open
Abstract
The prevalence of Legionella pneumophilia in water systems of residential facilities in Kuwait was performed during the period from November 2007 to November 2011. A total of 204 water samples collected from faucets and showerheads in bathrooms (n = 82), taps in kitchens (n = 51), and water tanks (n = 71), from different locations of residential facilities in Kuwait were screened for Legionella pneumophila by the standard culture method and by real time polymerase chain reaction (RT-PCR). Out of the 204 samples, 89 (43.6%) samples were positive for Legionella spp., 48 (23.5%) samples were detected by the standard culture method, and 85 (41.7%) were detected by RT-PCR. Of the culture positive Legionella samples, counts ranged between 10 to 2250 CFU/L. Serological typing of 48 Legionella isolates revealed that 6 (12.5%) of these isolates belonged to Legionella pneumophila serogroup 1, 37 (77.1%) isolates to Legionella pneumophila serogroup 3, and 1 isolate each (2.1%) belonged to serogroups 4, 7, and 10. The minimum inhibitory concentration (MICs) of the 46 environmental L. pneumophila isolates against the 10 antimicrobials commonly used for Legionella infection treatments were determined. Rifampicin was found to be the most active against L. pneumophila serogroups isolates in vitro.
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37
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Janssen KPF, Knez K, Vanysacker L, Schrooten J, Spasic D, Lammertyn J. Enabling fiber optic serotyping of pathogenic bacteria through improved anti-fouling functional surfaces. NANOTECHNOLOGY 2012; 23:235503. [PMID: 22609831 DOI: 10.1088/0957-4484/23/23/235503] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Significant research efforts are continually being directed towards the development of sensitive and accurate surface plasmon resonance biosensors for sequence specific DNA detection. These sensors hold great potential for applications in healthcare and diagnostics. However, the performance of these sensors in practical usage scenarios is often limited due to interference from the sample matrix. This work shows how the co-immobilization of glycol(PEG) diluents or 'back filling' of the DNA sensing layer can successfully address these problems. A novel SPR based melting assay is used for the analysis of a synthetic oligomer target as well as PCR amplified genomic DNA extracted from Legionella pneumophila. The benefits of sensing layer back filling on the assay performance are first demonstrated through melting analysis of the oligomer target and it is shown how back filling enables accurate discrimination of Legionella pneumophila serogroups directly from the PCR reaction product with complete suppression of sensor fouling.
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Affiliation(s)
- K P F Janssen
- BIOSYST-MeBioS, KU Leuven, Willem De Croylaan 42, Leuven, Belgium
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Touron-Bodilis A, Pougnard C, Frenkiel-Lebossé H, Hallier-Soulier S. Usefulness of real-time PCR as a complementary tool to the monitoring of Legionella spp. and Legionella pneumophila by culture in industrial cooling systems. J Appl Microbiol 2011; 111:499-510. [PMID: 21624019 DOI: 10.1111/j.1365-2672.2011.05063.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS This study was designed to evaluate the usefulness of quantification by real-time PCR as a management tool to monitor concentrations of Legionella spp. and Legionella pneumophila in industrial cooling systems and its ability to anticipate culture trends by the French standard method (AFNOR T90-431). METHODS AND RESULTS Quantifications of Legionella bacteria were achieved by both methods on samples from nine cooling systems with different water qualities. Proportion of positive samples for L. pneumophila quantified by PCR was clearly lower in deionized or river waters submitted to a biocide treatment than in raw river waters, while positive samples for Legionella spp. were quantified for almost all the samples. For some samples containing PCR inhibitors, high quantification limits (up to 4·80 × 10(5) GU l(-1) ) did not allow us to quantify L. pneumophila, when they were quantified by culture. Finally, the monitoring of concentrations of L. pneumophila by both methods showed similar trends for 57-100% of the samples. CONCLUSIONS These results suggest that, if some methodological steps designed to reduce inhibitory problems and thus decrease the quantification limits, could be developed to quantify Legionella in complex waters, the real-time PCR could be a valuable complementary tool to monitor the evolution of L. pneumophila concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY This study shows the possibility of using real-time PCR to monitor L. pneumophila proliferations in cooling systems and the importance to adapt nucleic acid extraction and purification protocols to raw waters.
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Affiliation(s)
- A Touron-Bodilis
- EDF Research and Development, Laboratoire National d'Hydraulique et d'Environnement, Chatou Cedex, France.
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39
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Update on the Detection and Characterization of Bacterial Pathogens by Nucleic Acid Amplification. Mol Microbiol 2011. [DOI: 10.1128/9781555816834.ch23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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40
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Koo O, Aroonnual A, Bhunia A. Human heat-shock protein 60 receptor-coated paramagnetic beads show improved capture of Listeria monocytogenes in the presence of other Listeria in food. J Appl Microbiol 2011; 111:93-104. [DOI: 10.1111/j.1365-2672.2011.05040.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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41
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Lee JV, Lai S, Exner M, Lenz J, Gaia V, Casati S, Hartemann P, Lück C, Pangon B, Ricci ML, Scaturro M, Fontana S, Sabria M, Sánchez I, Assaf S, Surman-Lee S. An international trial of quantitative PCR for monitoring Legionella in artificial water systems. J Appl Microbiol 2011; 110:1032-44. [PMID: 21276147 PMCID: PMC3564408 DOI: 10.1111/j.1365-2672.2011.04957.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 01/11/2011] [Accepted: 01/21/2011] [Indexed: 11/29/2022]
Abstract
AIMS To perform an international trial to derive alert and action levels for the use of quantitative PCR (qPCR) in the monitoring of Legionella to determine the effectiveness of control measures against legionellae. METHODS AND RESULTS Laboratories (7) participated from six countries. Legionellae were determined by culture and qPCR methods with comparable detection limits. Systems were monitored over ≥10 weeks. For cooling towers (232 samples), there was a significant difference between the log mean difference between qPCR (GU l(-1) ) and culture (CFU l(-1) ) for Legionella pneumophila (0·71) and for Legionella spp. (2·03). In hot and cold water (506 samples), the differences were less, 0·62 for Leg. pneumophila and 1·05 for Legionella spp. Results for individual systems depended on the nature of the system and its treatment. In cooling towers, Legionella spp. GU l(-1) always exceeded CFU l(-1) , and usually Legionella spp. were detected by qPCR when absent by culture. The pattern of results by qPCR for Leg. pneumophila followed the culture trend. In hot and cold water, culture and qPCR gave similar results, particularly for Leg. pneumophila. There were some marked exceptions with temperatures ≥50°C, or in the presence of supplementary biocides. Action and alert levels for qPCR were derived that gave results comparable to the application of the European Guidelines based on culture. Algorithms are proposed for the use of qPCR for routine monitoring. CONCLUSIONS Action and alert levels for qPCR can be adjusted to ensure public health is protected with the benefit that remedial actions can be validated earlier with only a small increase in the frequency of action being required. SIGNIFICANCE AND IMPACT OF THE STUDY This study confirms it is possible to derive guidelines on the use of qPCR for monitoring the control of legionellae with consequent improvement to response and public health protection.
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Affiliation(s)
- J V Lee
- Health Protection Agency, London, UK Institute for Hygiene and Public Health, Universität Bonn, Bonn, Germany Istituto Cantonale di Microbiologia, Bellinzona, Switzerland CHU Nancy, Nancy, France Institute of Medical Microbiology and Hygiene, University of Technology, Dresden, Germany Unité de Microbiologie-Hygiène, CH Versailles, Versailles, France Istituto Superiore di Sanità, Roma, Italy Autonomous University of Barcelona, Barcelona, Spain Pall GeneSystems, Bruz, France
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42
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Allegra S, Girardot F, Grattard F, Berthelot P, Helbig J, Pozzetto B, Riffard S. Evaluation of an immunomagnetic separation assay in combination with cultivation to improveLegionella pneumophilaserogroup 1 recovery from environmental samples. J Appl Microbiol 2011; 110:952-61. [DOI: 10.1111/j.1365-2672.2011.04955.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kim GY, Wang X, Son A. Inhibitor resistance and in situ capability of nanoparticle based gene quantification. ACTA ACUST UNITED AC 2011; 13:1344-50. [DOI: 10.1039/c0em00566e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Fittipaldi M, Codony F, Adrados B, Camper AK, Morató J. Viable real-time PCR in environmental samples: can all data be interpreted directly? MICROBIAL ECOLOGY 2011; 61:7-12. [PMID: 20632000 DOI: 10.1007/s00248-010-9719-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Accepted: 06/25/2010] [Indexed: 05/25/2023]
Abstract
Selective nucleic acid intercalating dyes--ethidium monoazide (EMA) and propidium monoazide (PMA)--represent one of the most successful recent approaches to detect viable cells (as defined by an intact cell membrane) by PCR and have been effectively evaluated in different microorganisms. However, some practical limitations were found, especially in environmental samples. The aim of this work was to show that in the application of viable real-time PCR, there may be significant biases and to propose a strategy for overcoming some of these problems. We present an approach based on the combination of three real-time PCR amplifications for each sample that should provide an improved estimation of the number of viable cells. This approach could be useful especially when it is difficult to determine a priori how to optimize methods using PMA or EMA. Although further studies are required to improve viable real-time PCR methods, the concept as outlined here presents an interesting future research direction.
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Affiliation(s)
- Mariana Fittipaldi
- Laboratori de Microbiologia Sanitària i Mediambiental (MSMLab)-Aquasost, UNESCO Chair in Sustainability, Universitat Politècnica de Catalunya, C/Violinista Vellsolà 37, 08222, Terrassa, Barcelona, Spain
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45
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Specific real-time PCR for simultaneous detection and identification of Legionella pneumophila serogroup 1 in water and clinical samples. Appl Environ Microbiol 2010; 77:1708-17. [PMID: 21193672 DOI: 10.1128/aem.02261-10] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Legionella pneumophila, a bacterium that replicates within aquatic amoebae and persists in the environment as a free-living microbe, is the causative agent of Legionnaires' disease. Among the many Legionella species described, L. pneumophila is associated with 90% of human disease, and within the 15 serogroups (Sg), L. pneumophila Sg1 causes more than 84% of Legionnaires' disease worldwide. Thus, rapid and specific identification of L. pneumophila Sg1 is of the utmost importance for evaluation of the contamination of collective water systems and the risk posed. Previously we had shown that about 20 kb of the 33-kb locus carrying the genes coding for the proteins involved in lipopolysaccharide biosynthesis (LPS gene cluster) by L. pneumophila was highly specific for Sg1 strains and that three genes (lpp0831, wzm, and wzt) may serve as genetic markers. Here we report the sequencing and comparative analyses of this specific region of the LPS gene cluster in L. pneumophila Sg6, -10, -12, -13, and -14. Indeed, the wzm and wzt genes were present only in the Sg1 LPS gene cluster, which showed a very specific gene content with respect to the other five serogroups investigated. Based on this observation, we designed primers and developed a classical and a real-time PCR method for the detection and simultaneous identification of L. pneumophila Sg1 in clinical and environmental isolates. Evaluation of the selected primers with 454 Legionella and 38 non-Legionella strains demonstrated 100% specificity. Sensitivity, specificity, and predictive values were further evaluated with 209 DNA extracts from water samples of hospital water supply systems and with 96 respiratory specimens. The results showed that the newly developed quantitative Sg1-specific PCR method is a highly specific and efficient tool for the surveillance and rapid detection of high-risk L. pneumophila Sg1 in water and clinical samples.
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Stoeckel DM, Stelzer EA, Dick LK. Evaluation of two spike-and-recovery controls for assessment of extraction efficiency in microbial source tracking studies. WATER RESEARCH 2009; 43:4820-4827. [PMID: 19589555 DOI: 10.1016/j.watres.2009.06.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 06/04/2009] [Accepted: 06/10/2009] [Indexed: 05/28/2023]
Abstract
Quantitative PCR (qPCR), applied to complex environmental samples such as water, wastewater, and feces, is susceptible to methodological and sample related biases. In this study, we evaluated two exogenous DNA spike-and-recovery controls as proxies for recovery efficiency of Bacteroidales 16S rDNA gene sequences (AllBac and qHF183) that are used for microbial source tracking (MST) in river water. Two controls--(1) the plant pathogen Pantoea stewartii, carrying the chromosomal target gene cpsD, and (2) Escherichia coli, carrying the plasmid-borne target gene DsRed2--were added to raw water samples immediately prior to concentration and DNA extraction for qPCR. When applied to samples processed in replicate, recovery of each control was positively correlated with the observed concentration of each MST marker. Adjustment of MST marker concentrations according to recovery efficiency reduced variability in replicate analyses when consistent processing and extraction methodologies were applied. Although the effects of this procedure on accuracy could not be tested due to uncertainties in control DNA concentrations, the observed reduction in variability should improve the strength of statistical comparisons. These findings suggest that either of the tested spike-and-recovery controls can be useful to measure efficiency of extraction and recovery in routine laboratory processing.
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Affiliation(s)
- Donald M Stoeckel
- US Geological Survey, Ohio Water Microbiology Laboratory, Columbus, OH 43229, USA
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47
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Bonetta S, Bonetta S, Ferretti E, Balocco F, Carraro E. Evaluation of Legionella pneumophila contamination in Italian hotel water systems by quantitative real-time PCR and culture methods. J Appl Microbiol 2009; 108:1576-83. [PMID: 19796090 DOI: 10.1111/j.1365-2672.2009.04553.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS This study was designed to define the extent of water contamination by Legionella pneumophila of certain Italian hotels and to compare quantitative real-time PCR with the conventional culture method. METHODS AND RESULTS Nineteen Italian hotels of different sizes were investigated. In each hotel three hot water samples (boiler, room showers, recycling) and one cold water sample (inlet) were collected. Physico-chemical parameters were also analysed. Legionella pneumophila was detected in 42% and 74% of the hotels investigated by the culture method and by real-time PCR, respectively. In 21% of samples analysed by the culture method, a concentration of >10(4) CFU l(-1) was found, and Leg. pneumophila serogroup 1 was isolated from 10.5% of the hotels. The presence of Leg. pneumophila was significantly influenced by water sample temperature, while no association with water hardness or residual-free chlorine was found. CONCLUSIONS This study showed a high percentage of buildings colonized by Leg. pneumophila. Moreover, real-time PCR proved to be sensitive enough to detect lower levels of contamination than the culture method. SIGNIFICANCE AND IMPACT OF THE STUDY This study indicates that the Italian hotels represent a possible source of risk for Legionnaires' disease and confirms the sensitivity of the molecular method. To our knowledge, this is the first report to demonstrate Legionella contamination in Italian hotels using real-time PCR and culture methods.
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Affiliation(s)
- Sa Bonetta
- Dipartimento di Scienze dell'Ambiente e della Vita, University of Piemonte Orientale A. Avogadro, Alessandria, Italy
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48
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Viability PCR, a culture-independent method for rapid and selective quantification of viable Legionella pneumophila cells in environmental water samples. Appl Environ Microbiol 2009; 75:3502-12. [PMID: 19363080 DOI: 10.1128/aem.02878-08] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PCR-based methods have been developed to rapidly screen for Legionella pneumophila in water as an alternative to time-consuming culture techniques. However, these methods fail to discriminate between live and dead bacteria. Here, we report a viability assay (viability PCR [v-PCR]) for L. pneumophila that combines ethidium monoazide bromide with quantitative real-time PCR (qPCR). The ability of v-PCR to differentiate viable from nonviable L. pneumophila cells was confirmed with permeabilizing agents, toluene, or isopropanol. v-PCR suppressed more than 99.9% of the L. pneumophila PCR signal in nonviable cultures and was able to discriminate viable cells in mixed samples. A wide range of physiological states, from culturable to dead cells, was observed with 64 domestic hot-water samples after simultaneous quantification of L. pneumophila cells by v-PCR, conventional qPCR, and culture methods. v-PCR counts were equal to or higher than those obtained by culture and lower than or equal to conventional qPCR counts. v-PCR was used to successfully monitor in vitro the disinfection efficacy of heating to 70 degrees C and glutaraldehyde and chlorine curative treatments. The v-PCR method appears to be a promising and rapid technique for enumerating L. pneumophila bacteria in water and, in comparison with conventional qPCR techniques used to monitor Legionella, has the advantage of selectively amplifying only viable cells.
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PCR-coupled electrochemical sensing of Legionella pneumophila. Biosens Bioelectron 2009; 24:2390-6. [DOI: 10.1016/j.bios.2008.12.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 11/20/2008] [Accepted: 12/09/2008] [Indexed: 11/17/2022]
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A PCR-based method for monitoring Legionella pneumophila in water samples detects viable but noncultivable legionellae that can recover their cultivability. Appl Environ Microbiol 2008; 74:4817-24. [PMID: 18515476 DOI: 10.1128/aem.02899-07] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Legionella pneumophila is the causative agent of Legionnaires' disease. This bacterium is ubiquitous in aqueous environments and uses amoebae as an intracellular replicative niche. Real-time PCR has been developed for rapid detection of Legionella DNA in water samples. In addition to culturable bacteria, this method may also detect dead and viable but noncultivable (VBNC) legionellae. In order to understand the significance of positive PCR results in this setting, we prepared water samples containing known concentrations of L. pneumophila and analyzed them comparatively by means of conventional culture, real-time PCR, viability labeling, and immunodetection (solid-phase cytometry). We also examined the influence of chlorination on the results of the four methods. The different techniques yielded similar results for nonchlorinated water samples but not for chlorinated samples. After treatment for 24 h with 0.5 and 1 ppm chlorine, all cultures were negative, PCR and immunodetection showed about 10(6) genome units and bacteria/ml, and total-viable-count (TVC) labeling detected 10(5) and 10(2) metabolically active bacteria/ml, respectively. Thus, PCR also detected bacteria that were VBNC. The recoverability of VBNC forms was confirmed by 5 days of coculture with Acanthamoeba polyphaga. Therefore, some TVC-positive bacteria were potentially infective. These data show that L. pneumophila PCR detects not only culturable bacteria but also VBNC forms and dead bacterial DNA at low chlorine concentrations.
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