scholarly journals Rapid Detection of Legionella pneumophila in Drinking Water, Based on Filter Immunoassay and Chronoamperometric Measurement

Biosensors ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 102
Author(s):  
Josune J. Ezenarro ◽  
Noemí Párraga-Niño ◽  
Miquel Sabrià ◽  
Fancisco Javier Del Campo ◽  
Francesc-Xavier Muñoz-Pascual ◽  
...  
Keyword(s):  
Drinking Water ◽  
Legionella Pneumophila ◽  
Detection System ◽  
Low Cost ◽  
Water Systems ◽  
Bacterial Concentration ◽  
Sample Concentration ◽  
Conventional Culture ◽  
Portable Detection ◽  
Freshwater Environments

Legionella is a pathogenic bacterium, ubiquitous in freshwater environments and able to colonise man-made water systems from which it can be transmitted to humans during outbreaks. The prevention of such outbreaks requires a fast, low cost, automated and often portable detection system. In this work, we present a combination of sample concentration, immunoassay detection, and measurement by chronoamperometry. A nitrocellulose microfiltration membrane is used as support for both the water sample concentration and the Legionella immunodetection. The horseradish peroxidase enzymatic label of the antibodies permits using the redox substrate 3,3′,5,5′-Tetramethylbenzidine to generate current changes proportional to the bacterial concentration present in drinking water. Carbon screen-printed electrodes are employed in the chronoamperometric measurements. Our system reduces the detection time: from the 10 days required by the conventional culture-based methods, to 2–3 h, which could be crucial to avoid outbreaks. Additionally, the system shows a linear response (R2 value of 0.99), being able to detect a range of Legionella concentrations between 101 and 104 cfu·mL−1 with a detection limit (LoD) of 4 cfu·mL−1.

scholarly journals LAMP assay coupled with CRISPR/Cas12a system for portable detection of African swine fever virus

2021 ◽  
Author(s):  
Bo YANG ◽  
zhengwang shi ◽  
Yuan Ma ◽  
Lijuan Wang ◽  
Liyan Cao ◽  
...  
Keyword(s):  
Real Time ◽  
Detection System ◽  
African Swine Fever Virus ◽  
Low Cost ◽  
African Swine Fever ◽  
Lamp Assay ◽  
Cross Reactivity ◽  
Clinical Samples ◽  
Portable Detection ◽  
Real Time Qpcr

African swine fever (ASF) is one of the most severe infectious diseases of pigs. In this study, a LAMP assay coupled with the CRISPR Cas12a system was established in one tube for the detection of the ASFV p72 gene. The single-strand DNA-fluorophore-quencher (ssDNA-FQ) reporters and CRISPR-derived RNA (crRNAs) were screened and selected for the CRISPR detection system. In combination with LAMP amplification assay, the detection limit for the LAMP-CRISPR assay can reach 7 copies/μl of p72 gene per reaction. Furthermore, this method displays no cross-reactivity with other porcine DNA or RNA viruses. The performance of the LAMP-CRISPR assay was compared with real-time qPCR tests for clinical samples, a good consistency between the LAMP-CRISPR assay and real-time qPCR was observed. In the current study, a LAMP coupled with the CRISPR detection method was developed. The method shed a light on the convenient, portable, low cost, highly sensitive and specific detection of ASFV, demonstrating a great application potential for monitoring on-site ASFV in the field.

scholarly journals Is a Proactive Approach to Controlling Legionella in the Environment Justified?

2021 ◽  
Vol 59 (3) ◽  
Author(s):  
Daniela Glažar Ivče ◽  
Dobrica Rončević ◽  
Marina Šantić ◽  
Arijana Cenov ◽  
Dijana Tomić Linšak ◽  
...  
Keyword(s):  
Drinking Water ◽  
Legionella Pneumophila ◽  
Cold Water ◽  
Aged Care ◽  
Water Systems ◽  
Hot Water ◽  
Plate Count ◽  
Surveillance Program ◽  
Adequate Treatment ◽  
Proactive Approach

Research background. Legionella are Gram-negative bacteria that are ubiquitous in the natural environment. Contaminated water in manmade water systems is a potential source of transmission of Legionnaires’ disease (LD). The aim of this study was to explore the prevalence of Legionella pneumophila (L. pneumophila) in the drinking water distribution system (DWDS) of Primorje-Gorski Kotar County (PGK County), Croatia, for the period 2013-2019, coupled with the incidence of LD. A number of L. pneumophila-positive samples (>100 CFU/L), serogroup distribution, and the degree of contamination of specific facilities (health & aged care, tourism, sports) were assessed. Based on the results obtained, the reasoning for the implementation of a mandatory Legionella environmental surveillance program was assessed. Experimental approach. Sample testing for Legionella was carried out according to ISO 1173. A Heterotrophic Plate Count (HPC) and P. aeruginosa were analysed along with the basic physico-chemical indicators of drinking water quality. The research period was divided into two parts, namely, the 2013-2018 period (before implementation of the prevention program, after the outbreak of LD), and year 2019 (proactive approach, no LD cases recorded). Results and conclusion. During the 7-year observation period in PGK County, an increase in the number of samples tested for Legionella was found. An increase in Legionella-positive samples (particularly pronounced during the warmer part of the year) was recorded, along with a growing trend in the number of reported LD cases. In addition to hot water systems, the risk of Legionella colonization also applies to cold water systems. Health & aged care facilities appear to be at highest risk. In addition to the higher proportion of positive samples and a higher degree of microbiological load at these facilities, the highest proportion of L. pneumophila SGs 2-14 was identified. Due to the diagnostic limitations of the applied tests, the number of LD cases is underdiagnosed. Novelty and scientific contribution. The introduction of a mandatory preventive approach to monitoring Legionella in DWDS water samples, along with the definition of national criteria for the interpretation of results, will create the preconditions for diagnosis and adequate treatment of larger numbers of LD cases.

scholarly journals A MEMS-Based Multi-Parameter Integrated Chip and Its Portable System for Water Quality Detection

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 63 ◽  
Author(s):  
Ziyue Wu ◽  
Jiaqi Wang ◽  
Chao Bian ◽  
Jianhua Tong ◽  
Shanhong Xia
Keyword(s):  
Water Quality ◽  
Copper Ions ◽  
Detection System ◽  
Low Cost ◽  
Temperature Response ◽  
High Sensitivity ◽  
Integrated Sensor ◽  
Quality Detection ◽  
Portable Detection ◽  
Portable System

As an important means to protect water resources, water quality detection is of great social and economic significance. Water quality detection sensors processed by micro-electro-mechanical system (MEMS) technology have the advantages of low-cost, small size, and high sensitivity. In this paper, a multi-parameter water quality detection integrated sensor chip is further studied, and a portable detection system using this chip is developed. Temperature, pH, oxidation-reduction potential (ORP), conductivity and concentration of copper ions (Cu2+) are selected as typical water quality parameters. Experiments of sensor calibrations using this portable detection system were performed in standard solutions. The sensor has a sensitivity of −57.34 mV/pH in pH detection and 5.95 Ω/°C in temperature response. ORP is directly detected by Pt microelectrode on the chip and the relative error is less than 3%. The electrode constant of the sensor is 1.416 cm−1 and the linearity is 0.9995 in conductivity detection. With the gold nanoparticles deposited on the electrode, the detection peak of Cu2+ appears at 280 mV and the sensor shows good linearity to the concentration of Cu2+ in the range of 0–0.6 mg/L. The detection limit of Cu2+ concentration is 2.33 μg/L. Through measurement and calculation, the accuracy of the portable system is within 4%. This portable multi-parameter water quality detection system with the MEMS-based integrated chip shows great potential in the field and fast detection.

Survival and multiplication of Legionella pneumophila in municipal drinking water systems.

1987 ◽  
Vol 53 (5) ◽  
pp. 979-986 ◽  
Author(s):  
S J States ◽  
L F Conley ◽  
J M Kuchta ◽  
B M Oleck ◽  
M J Lipovich ◽  
...  
Keyword(s):  
Drinking Water ◽  
Legionella Pneumophila ◽  
Water Systems ◽  
Drinking Water Systems

Piped Drinking Water Sampling Plan for Small Water Systems in Singapore - A Regulator's Perspective

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
Pranav S. Joshi ◽  
Ramnath Vaidyanathan ◽  
Lam Chun Hsiang ◽  
S Satish Appoo
Keyword(s):  
Drinking Water ◽  
Low Cost ◽  
Water Systems ◽  
Sampling Plan ◽  
Water Sampling ◽  
Unique Challenge ◽  
Small Water ◽  
Economy Of Scale ◽  
Organizational Controls ◽  
Piped Water

Small piped drinking water systems pose a unique challenge to the regulatory authorities since the owners/operators of such systems often lack technical expertise, resources and organizational controls to effectively operate their treatment systems, unlike the large utilities that have the economy of scale to address these issues in an optimal manner. With the discovery of new non-conventional sources of water and the continuous development of low-cost water treatment processes, the number of small suppliers is likely to grow worldwide in the future, especially in those remote areas/islands where drinking water is not easily available. In order to ensure that these suppliers are able to detect any health risk to the consumers in a timely manner, it is imperative to develop a water sampling plan that is comprehensive enough, yet flexible and practical to implement. This paper highlights Singapore's regulatory experience in prescribing, developing and monitoring the implementation of piped water sampling plans by small water suppliers.

scholarly journals Detection of Particulate Matters with a Field-Portable Microscope Using Side-Illuminated Total Internal Reflection

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2745
Author(s):  
Haechang Yang ◽  
Sanghoon Shin ◽  
Dongmin Seo ◽  
Jaewon Park ◽  
Sungkyu Seo
Keyword(s):  
Total Internal Reflection ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Internal Reflection ◽  
Dust Particles ◽  
Halogen Lamp ◽  
Signal To Noise ◽  
Portable Detection ◽  
Transmission Microscope

Field-portable observation and analysis of particulate matter (PM) is required to enhance healthy lives. Various types of the PM measurement methods are in use; however, each of these methods has significant limitations in that real time measurement is impossible, the detection system is bulky, or the measurement accuracy is insufficient. In this work, we introduce an optical method to perform a fast and accurate PM analysis with a higher-contrast microscopic image enabled by a side-illuminated total internal reflection (TIR) technique to be implemented in a compact device. The superiority of the proposed method was quantitatively demonstrated by comparing the signal-to-noise ratio of the proposed side-illuminated TIR method with a traditional halogen lamp-based transmission microscope. With the proposed device, signal-to-noise ratios (SNRs) for microbeads (5~20 µm) and ultrafine dust particles (>5 µm) increased 4.5~17 and 4~10 dB, respectively, compared to the conventional transmission microscope. As a proof of concept, the proposed method was also applied to a low-cost commercial smartphone toy microscope enabling field-portable detection of PMs. We believe that the proposed side-illuminated TIR PM detection device holds significant advantages over other commonly used systems due to its sufficient detection capability along with simple and compact configuration as well as low cost.

scholarly journals LAMP assay coupled with CRISPR/Cas12a system for portable detection of African swine fever virus

2021 ◽  
Author(s):  
Bo YANG ◽  
zhengwang shi ◽  
Yuan Ma ◽  
Lijuan Wang ◽  
Liyan Cao ◽  
...  
Keyword(s):  
Real Time ◽  
Detection System ◽  
African Swine Fever Virus ◽  
Low Cost ◽  
African Swine Fever ◽  
Lamp Assay ◽  
Cross Reactivity ◽  
Clinical Samples ◽  
Portable Detection ◽  
Real Time Qpcr

African swine fever (ASF) is one of the most severe infectious diseases of pigs. In this study, a LAMP assay coupled with the CRISPR Cas12a system was established in one tube for the detection of the ASFV p72 gene. The single-strand DNA-fluorophore-quencher (ssDNA-FQ) reporter and CRISPR-derived RNA (crRNAs) were screened and selected for the CRISPR detection system. In combination with LAMP amplification assay, the detection limit for the LAMP-CRISPR assay can reach 7 copies/μl of p72 gene per reaction. Furthermore, this method displays no cross-reactivity with other porcine DNA or RNA viruses. The performance of the LAMP-CRISPR assay was compared with real-time qPCR tests for clinical samples, a good consistency between the LAMP-CRISPR assay and real-time qPCR was observed. The method shed a light on the convenient, portable, low cost, highly sensitive and specific detection of ASFV, demonstrating a great application potential for monitoring on-site ASFV in the field.

scholarly journals Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice

2000 ◽  
Vol 66 (8) ◽  
pp. 3363-3367 ◽  
Author(s):  
James T. Walker ◽  
David J. Bradshaw ◽  
Allan M. Bennett ◽  
Martin R. Fulford ◽  
Michael V. Martin ◽  
...  
Keyword(s):  
Drinking Water ◽  
Legionella Pneumophila ◽  
Biofilm Formation ◽  
Water Systems ◽  
Oral Streptococci ◽  
Analysis Techniques ◽  
B Virus ◽  
Dental Practices ◽  
Light Staining ◽  
Image Analysis Techniques

ABSTRACT Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 105CFU · ml−1; in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this “viable by BacLight” fraction produced colonies on agar plates. Legionella pneumophila,Mycobacterium spp., Candida spp., andPseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci andFusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered “cleaner” than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.

scholarly journals Chlorine and Monochloramine Disinfection ofLegionella pneumophilaColonizing Copper and Polyvinyl Chloride Drinking Water Biofilms

2019 ◽  
Vol 85 (7) ◽  
Author(s):  
Helen Y. Buse ◽  
Brian J. Morris ◽  
Ian T. Struewing ◽  
Jeffrey G. Szabo
Keyword(s):  
Drinking Water ◽  
Polyvinyl Chloride ◽  
Legionella Pneumophila ◽  
Water Systems ◽  
Free Chlorine ◽  
Rrna Gene ◽  
Gene Transcript ◽  
Transcript Levels ◽  
Content Type ◽  
Water Based

ABSTRACTBuilding water systems promote the regrowth and survival of opportunistic pathogens, such asLegionella pneumophila, especially within biofilms, where most drinking water microbes reside. However, compared to their planktonic form, disinfection efficacy for the biofilm-associated forms of water-based pathogens is unclear. The aim of this study was to determine the effectiveness of free chlorine and monochloramine in the inactivation of biofilm-associatedL. pneumophilastrain Philadelphia-1 serogroup 1 (LpP1s1). Mature (1.5- to 2-year-old) drinking water biofilms were developed on copper (Cu) and polyvinyl chloride (PVC) slides within biofilm annular reactors, then colonized with LpP1s1 at approximately 4 log10CFU cm−2and exposed to 2 mg liter−1of free chlorine or monochloramine.Ct(disinfectant concentration × time, expressed as mg min liter−1) inactivation values for 2-, 3-, and 4-log10reductions of planktonic and biofilm LpP1s1 were determined. For planktonic LpP1s1, free chlorine was more effective at inactivation than was monochloramine treatment, and for biofilm-associated LpP1s1, monochloramine was more effective on Cu biofilms while free chlorine was more effective on PVC biofilms. In contrast to monochloramine, free chlorine treatment of Cu and PVC biofilms, negatively impacted LpP1s1 16S rRNA gene transcript levels and may act synergistically with Cu surfaces to further reduce transcript levels. Moreover, LpP1s1 cells shed from biofilms into the bulk water were more resistant to disinfection than were prepared planktonic LpP1s1 cells. Results from this study indicate that biofilm association, disinfectant type, and substratum play an important role in the survival ofLegionella pneumophilain building water systems.IMPORTANCEMicrobial regrowth within building water systems are promoted by water stagnation, low disinfectant residual, high surface-to-volume ratio, amenable growth temperatures, and colonization of drinking water biofilms. Moreover, biofilms provide protection from environmental stresses, access to higher levels of nutrients, and opportunities for symbiotic interactions with other microbes. Disinfectant efficacy information is historically based on inactivation of pathogens in their planktonic, free-floating forms. However, due to the ecological importance of drinking water biofilms for pathogen survival, this study evaluated the efficacy of two common disinfectants, free chlorine and monochloramine, onLegionella pneumophilacolonizing mature, drinking water biofilms established on copper and PVC surfaces. Results showed that inactivation was dependent on the disinfectant type and biofilm substratum. Overall, this, and other related research, will provide a better understanding ofLegionellaecological stability and survival and aid policy makers in the management of exposure risks to water-based pathogens within building water systems.

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