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Teramura H, Ogura A, Everis L, Betts G. MC-Media Pad CC for Enumeration of Total Coliforms in a Variety of Foods. J AOAC Int 2020; 102:1492-1501. [PMID: 33216927 DOI: 10.1093/jaoac/102.5.1492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Indexed: 11/14/2022]
Abstract
BACKGROUND Standard coliform count methods require the preparation of agar, the use of the pour-plate technique, the overlay of agar, and in some cases, the transfer of suspect colonies to broth medium for confirmation. The MC-Media Pad CC for the enumeration of coliforms is a ready-to-use dehydrated sheet medium with no agar preparation, no spreader, and no confirmation step required. OBJECTIVE Using a paired study design, the MC-Media Pad CC was compared to standard method ISO 4832:2006 for 10 matrixes including raw ground pork, raw chicken, cream, cream cheese, ready-to-cook vegetable mix, vegetable juice, cooked prawns, crab pâté, ham sandwiches, and cooked rice. METHODS Each matrix was tested at three levels of coliform contamination (approximately 102, 104, and 106 CFU/g). Five replicate 10 g test portions per level were tested in a paired comparison by the MC-Media Pad CC and ISO 4832:2006 methods. In addition, inclusivity/exclusivity, robustness, and product consistency and stability were evaluated. RESULTS The candidate and reference methods demonstrated SDs ranging from 0.027 to 0.264 and 0.025 to 0.157, respectively. The difference of means ranged from -0.015 to 0.381, showing no practical difference between the methods. The MC-Media Pad CC detected 58/62 inclusivity strains and correctly excluded 26/31 exclusivity organisms, similar to the reference method. Robustness testing demonstrated no significant change in results when small changes were made to sample volume, incubation temperature, and incubation time. The product consistency study demonstrated no significant difference between lots of product and supported the 1.5 year shelf life. CONCLUSIONS The results support the conclusions that the MC-Media Pad CC is a suitable alternative to the ISO 4832:2006 reference method for the matrixes examined and the data support AOAC Performance Tested MethodSM certification.
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Affiliation(s)
- Hajime Teramura
- JNC Corporation,Yokohama Research Center, 5-1, Ookawa, Kanazawa-ku, Yokohama, Japan 236-8605
| | - Aya Ogura
- JNC Corporation,Yokohama Research Center, 5-1, Ookawa, Kanazawa-ku, Yokohama, Japan 236-8605
| | - Linda Everis
- Campden BRI Ltd, Station Rd, Chipping Campden, United Kingdom GL55 6LD
| | - Gail Betts
- Campden BRI Ltd, Station Rd, Chipping Campden, United Kingdom GL55 6LD
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Wang S, Zheng L, Cai G, Liu N, Liao M, Li Y, Zhang X, Lin J. A microfluidic biosensor for online and sensitive detection of Salmonella typhimurium using fluorescence labeling and smartphone video processing. Biosens Bioelectron 2019; 140:111333. [PMID: 31153017 DOI: 10.1016/j.bios.2019.111333] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 05/10/2019] [Accepted: 05/15/2019] [Indexed: 11/18/2022]
Abstract
Early screening of foodborne pathogens is a key to ensure food safety. In this study, we developed a microfluidic biosensor for online and sensitive detection of Salmonella based on immunomagnetic separation, fluorescence labeling and smartphone video processing. First, the immune magnetic nanoparticles were used to specifically separate and efficiently concentrate the target bacteria and the magnetic bacteria were formed. Then, the magnetic bacteria were labeled with the immune fluorescent microspheres and the fluorescent bacteria were formed. Finally, the fluorescent bacteria were continuously injected into the microfluidic chip on the smartphone-based fluorescent microscopic system, and the fluorescent spots were online counted using the smartphone App based on inter-frame difference algorithm to obtain the amount of the target bacteria. Under the optimal conditions, this proposed biosensor was able to quantitatively detect Salmonella typhimurium ranging from 1.4 × 102 to 1.4 × 106 CFU/mL, and its lower detection limit was 58 CFU/mL. This biosensor could be extended for detection of multiple foodborne pathogens using different fluorescent materials.
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Affiliation(s)
- Siyuan Wang
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing, 100083, China
| | - Lingyan Zheng
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing, 100083, China
| | - Gaozhe Cai
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing, 100083, China
| | - Ning Liu
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing, 100083, China
| | - Ming Liao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China
| | - Yanbin Li
- Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Xibin Zhang
- College of Food Science and Engineering, Shandong Agricultural University, Taian, 271018, China
| | - Jianhan Lin
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture and Rural Affairs, China Agricultural University, Beijing, 100083, China.
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Abstract
Tuberculosis is a difficult disease to treat, a process made more harder as tools to monitor treatment response only provide a result long after the patient has provided a sample. The mycobacterial load assay (MBLA) provides a simple molecular test to quantify and determine the viability of M. tuberculosis in human or other samples.
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Affiliation(s)
- Stephen H Gillespie
- School of Medicine, University of St Andrews, North Haugh, North Street, St Andrews, KY16 9AJ, UK.
| | - Wilber Sabiiti
- School of Medicine, University of St Andrews, North Haugh, North Street, St Andrews, KY16 9AJ, UK
| | - Katarina Oravcova
- School of Medicine, University of St Andrews, North Haugh, North Street, St Andrews, KY16 9AJ, UK
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Park JW, Park CW, Lee SH, Hwang J. Fast monitoring of indoor bioaerosol concentrations with ATP bioluminescence assay using an electrostatic rod-type sampler. PLoS One 2015; 10:e0125251. [PMID: 25950929 PMCID: PMC4423956 DOI: 10.1371/journal.pone.0125251] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/22/2015] [Indexed: 01/28/2023] Open
Abstract
A culture-based colony counting method is the most widely used analytical technique for monitoring bioaerosols in both indoor and outdoor environments. However, this method requires several days for colony formation. In this study, our goal was fast monitoring (Sampling: 3 min, Detection: < 1 min) of indoor bioaerosol concentrations with ATP bioluminescence assay using a bioaerosol sampler. For this purpose, a novel hand-held electrostatic rod-type sampler (110 mm wide, 115 mm long, and 200 mm tall) was developed and used with a commercial luminometer, which employs the Adenosine triphosphate (ATP) bioluminescence method. The sampler consisted of a wire-rod type charger and a cylindrical collector, and was operated with an applied voltage of 4.5 kV and a sampling flow rate of 150.7 lpm. Its performance was tested using Staphylococcus epidermidis which was aerosolized with an atomizer. Bioaerosol concentrations were measured using ATP bioluminescence method with our sampler and compared with the culture-based method using Andersen cascade impactor under controlled laboratory conditions. Indoor bioaerosol concentrations were also measured using both methods in various indoor environments. A linear correlation was obtained between both methods in lab-tests and field-tests. Our proposed sampler with ATP bioluminescence method may be effective for fast monitoring of indoor bioaerosol concentrations.
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Affiliation(s)
- Ji-Woon Park
- School of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea
| | - Chul Woo Park
- HAE Research and Development Center, LG Electronics, Seoul, Republic of Korea
| | - Sung Hwa Lee
- HAE Research and Development Center, LG Electronics, Seoul, Republic of Korea
| | - Jungho Hwang
- School of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea
- * E-mail:
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Abstract
BACKGROUND Mobile smart phones have become increasingly integrated into the practice of doctors and allied medical professionals. Recent studies suggest them to represent reservoirs for pathogens with potential to cause nosocomial infections. This study aimed to investigate the level of contamination on phones used on surgical wards and identify strategies for their safe use within clinical areas. METHODS Fifty mobile phones were taken from members of the multidisciplinary team working in a surgical unit. Phones were swabbed by two trained investigators using a standardised technique and samples streaked out using an automated specimen inoculator onto two types of culture media (Columbia blood agar and MacConkey agar). Colonies were identified and counted by a single trained investigator in a blinded fashion. Simultaneously a questionnaire investigating usage levels of phones was given to 150 healthcare workers. RESULTS Sixty per cent of phones sampled had some form of contaminant isolated from their phone. Thirty-one (62%) of phones had only three colonies or less isolated on medium. No pathogenic or drug resistant strains of bacteria were identified. A total of 88% of individuals sampled by questionnaire used their phone within the workplace of which 55% used it for clinical purposes. Sixty-three per cent expected there to be some form of contaminant on their phone with only 37% admitting to cleaning it regularly. Seventy-five per cent of people did not view a ban on phones as a practical solution was they found to be an infection risk. CONCLUSION Touch screen smart phones may be used safely in a clinical environment, with a low risk of cross-contamination of nosocomial bacteria to patients, in the setting of effective adherence to hand hygiene policies.
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Affiliation(s)
- D Mark
- Department of General Surgery, Ulster Hospital, Belfast, UK
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Affiliation(s)
- R A Stein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA. ,
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Wu YC, Kulbatski I, Medeiros PJ, Maeda A, Bu J, Xu L, Chen Y, DaCosta RS. Autofluorescence imaging device for real-time detection and tracking of pathogenic bacteria in a mouse skin wound model: preclinical feasibility studies. J Biomed Opt 2014; 19:085002. [PMID: 25089944 DOI: 10.1117/1.jbo.19.8.085002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/19/2014] [Indexed: 06/03/2023]
Abstract
Bacterial infection significantly impedes wound healing. Clinical diagnosis of wound infections is subjective and suboptimal, in part because bacteria are invisible to the naked eye during clinical examination. Moreover, bacterial infection can be present in asymptomatic patients, leading to missed opportunities for diagnosis and treatment. We developed a prototype handheld autofluorescence (AF) imaging device (Portable Real-time Optical Detection, Identification and Guidance for Intervention - PRODIGI) to noninvasively visualize and measure bacterial load in wounds in real time. We conducted preclinical pilot studies in an established nude mouse skin wound model inoculated with bioluminescent Staphylococcus aureus bacteria. We tested the feasibility of longitudinal AF imaging for in vivo visualization of bacterial load in skin wounds, validated by bioluminescence imaging. We showed that bacteria (S. aureus), occult to standard examination, can be visualized in wounds using PRODIGI. We also detected quantitative changes in wound bacterial load over time based on the antibiotic treatment and the correlation of bacterial AF intensity with bacterial load. AF imaging of wounds offers a safe, noninvasive method for visualizing the presence, location, and extent of bacteria as well as measuring relative changes in bacterial load in wounds in real time.
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Affiliation(s)
- Yichao Charlie Wu
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada
| | - Iris Kulbatski
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada
| | - Philip J Medeiros
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada
| | - Azusa Maeda
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, CanadabUniversity of Toronto, Department of Medical Biophysics, Faculty of Medicine, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Jiachuan Bu
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada
| | - Lizhen Xu
- University Health Network, Department of Biostatistics, 610 University Avenue, Toronto, Ontario M5G 2M9, CanadadUniversity of Toronto, Dalla Lana School of Public Health, 155 College Street, 6th Floor, Toronto, Ontario M5T 3M7, Canada
| | - Yonghong Chen
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada
| | - Ralph S DaCosta
- University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, Ontario M5G 2M9, CanadabUniversity of Toronto, Department of Medical Biophysics, Faculty of Medicine, 1 King's College Circle, Toronto, Ontario M5S 1A8, CanadaeUni
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Arienzo A, Losito F, Bottini G, Priolisi FR, Mari A, Visca P, Antonini G. A new device for the prompt diagnosis of urinary tract infections. Clin Chem Lab Med 2014; 52:1507-11. [PMID: 24914727 DOI: 10.1515/cclm-2014-0294] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/09/2014] [Indexed: 11/15/2022]
Abstract
BACKGROUND Urinary tract infections (UTIs) are among the most common infectious diseases. RESULTS obtained from conventional microbiological analysis of urine and antibiotic susceptibility testing are available only after a few days, delaying precise diagnosis and appropriate therapy. Micro Biological Survey (MBS) srl (a spin-off of Roma Tre University, Rome, Italy) has developed and patented an automated colorimetric test for rapid bacterial counting. In a preliminary validation study it was demonstrated that the results obtained with the MBS method are equivalent to the results obtained with conventional culture-based microbiological analysis. METHODS In this study, sterile urine samples were artificially contaminated with bacterial species that are most frequently responsible for UTIs. The MBS method was used to evaluate the presence of bacteria and their sensitivity to some of the most commonly used antibiotics in UTIs. RESULTS The MBS method was able to detect in a few hours the presence or absence of bacteria at clinically significant concentrations (>105 CFU/mL), and to provide their susceptibility pattern to a limited panel of antibiotics. DISCUSSION The results obtained demonstrate that the MBS point-of-care testing (POCT) device could be developed into a valuable aid for the management of UTIs, possibly addressing more precise diagnosis and appropriate therapy.
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Bajwa A, Tan ST, Mehta R, Bahreyni B. Rapid detection of viable microorganisms based on a plate count technique using arrayed microelectrodes. Sensors (Basel) 2013; 13:8188-98. [PMID: 23803788 PMCID: PMC3758590 DOI: 10.3390/s130708188] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/22/2013] [Accepted: 06/06/2013] [Indexed: 12/19/2022]
Abstract
Development of a miniaturized biosensor system that can be used for rapid detection and counting of microorganisms in food or water samples is described. The developed microsystem employs a highly sensitive impedimetric array of biosensors to monitor the growth of bacterial colonies that are dispersed across an agar growth medium. To use the system, a sample containing the bacteria is cultured above the agar layer. Using a multiplexing network, the electrical properties of the medium at different locations are continuously measured, recorded, and compared against a baseline signal. Variations of signals from different biosensors are used to reveal the presence of bacteria in the sample, as well as the locations of bacterial colonies across the biochip. This technique forms the basis for a label-free bacterial detection for rapid analysis of food samples, reducing the detection time by at least a factor of four compared to the current required incubation times of 24 to 72 hours for plate count techniques. The developed microsystem has the potential for miniaturization to a stage where it could be deployed for rapid analysis of food samples at commercial scale at laboratories, food processing facilities, and retailers.
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Affiliation(s)
- Avneet Bajwa
- Alberta Health Services, Calgary, AB T2N 2T9, Canada; E-Mail:
| | - Shaoqing Tim Tan
- School of Mechatronic Systems Engineering, Simon Fraser University, Surrey, BC V3T 0A3, Canada; E-Mail:
| | - Ram Mehta
- PBR Laboratories Inc., Edmonton, AB T6E 0P5, Canada; E-Mail:
| | - Behraad Bahreyni
- School of Mechatronic Systems Engineering, Simon Fraser University, Surrey, BC V3T 0A3, Canada; E-Mail:
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Suchwalko A, Buzalewicz I, Wieliczko A, Podbielska H. Bacteria species identification by the statistical analysis of bacterial colonies Fresnel patterns. Opt Express 2013; 21:11322-11337. [PMID: 23669989 DOI: 10.1364/oe.21.011322] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
It was demonstrated that statistical analysis of bacteria colonies Fresnel patterns recorded in the optical system with converging spherical wave illumination is suitable for highly effective bacteria species classification. The proposed method includes Fresnel patterns recording followed by image processing and the statistical analysis based on feature extraction, feature selection, classification and classification performance methods. Examination performed on various bacteria species (Salmonella enteritidis, Staphylococcus aureus, Staphylococcus intermedius, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Citrobacter freundii) revealed that the proposed method achieved very high accuracy of over 98%.
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Affiliation(s)
- Agnieszka Suchwalko
- Bio-Optics Group, Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
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Momeni SS, Tomline N, Ruby JD, Dasanayake AP. Evaluation of in-office dental unit waterline testing. Gen Dent 2012; 60:e142-e147. [PMID: 22623469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In-office dental unit waterline (DUWL) testing systems are commercially available for monitoring DUWL bacteria. The current study compared Aquasafe, Petrifilm, and Heterotrophic Plate Count Sampler (HPCS) with R2A plating methodology, considered the gold standard for enumerating heterotrophic bacteria in potable water. Samples were collected from 20 dental units. Heterotrophic bacterial counts of ≤500 CFUs/mL were used as the cut-off for assessing in-office testing compared to R2A laboratory plating. Validity was assessed using sensitivity and specificity, along with positive and negative predictive values. Results were also compared using concordance and kappa statistics. All in-office tests demonstrated 100% specificity and positive predictive values, while sensitivity and negative predictive values were low (Petrifilm, 57%/50%; HPCS, 50%/46%; Aquasafe, 21%/35%). Concordance and kappa values for agreement with R2A plating were as follows: Petrifilm 70% (κ = 0.44), HPCS 65% (κ = 0.38), and Aquasafe 45% (κ = 0.14). In-office DUWL testing with Aquasafe, Petrifilm, and HPCS agreed poorly with R2A plating methodology and is not valid or reliable as a means of accurately monitoring bacterial density in DUWL. These in-office test systems should not be used for assessing compliance with the ADA and CDC standard for acceptable heterotrophic bacterial counts in DUWLs (≤500 CFUs/mL).
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Affiliation(s)
- Stephanie S Momeni
- Department of Pediatric Dentistry, University of Alabama at Birmingham, USA
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Mader A, Gruber K, Castelli R, Hermann BA, Seeberger PH, Rädler JO, Leisner M. Discrimination of Escherichia coli strains using glycan cantilever array sensors. Nano Lett 2012; 12:420-423. [PMID: 22136522 DOI: 10.1021/nl203736u] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Carbohydrate-based sensors, that specifically detect sugar binding molecules or cells, are increasingly important in medical diagnostic and drug screening. Here we demonstrate that cantilever arrays functionalized with different mannosides allow the real-time detection of several Escherichia coli strains in solution. Cantilever deflection is thereby dependent on the bacterial strain studied and the glycan used as the sensing molecule. The cantilevers exhibit specific and reproducible deflection with a sensitivity range over four orders of magnitude.
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Affiliation(s)
- Andreas Mader
- Center for Nanoscience, Ludwig-Maximilians-Universität, Fakultät für Physik, Geschwister-Scholl-Platz 1, 80539 München, Germany
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Abstract
We demonstrate the use of a microfluidic device that accurately monitors bacteria levels in water. Fluorescent antibody labelled E. coli K12 bacteria in aqueous samples are flowed through the device, and spikes in the emission signal correspond to the presence of bacteria. Target bacteria could also be detected while suspended in a suspension of very low antibody concentration, suggesting that washing of bacteria could be avoided to make the detection automated and more rapid. Use of a microfluidic device will eventually enable quick on-site detection of bacteria using small quantities of sample.
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Affiliation(s)
- Ashish K Jha
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI 02881, USA
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Miranda OR, Li X, Garcia-Gonzalez L, Zhu ZJ, Yan B, Bunz UHF, Rotello VM. Colorimetric bacteria sensing using a supramolecular enzyme-nanoparticle biosensor. J Am Chem Soc 2011; 133:9650-3. [PMID: 21627131 PMCID: PMC3120917 DOI: 10.1021/ja2021729] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rapid and sensitive detection of pathogens is a key requirement for both environmental and clinical settings. We report here a colorimetric enzyme-nanoparticle conjugate system for detection of microbial contamination. In this approach, cationic gold nanoparticles (NPs) featuring quaternary amine headgroups are electrostatically bound to an enzyme [β-galactosidase (β-Gal)], inhibiting enzyme activity. Analyte bacteria bind to the NP, which releases the β-Gal and restores its activity, providing an enzyme-amplified colorimetric readout of the binding event. Using this strategy, we have been able to quantify bacteria at concentrations of 1 × 10(2) bacteria/mL in solution and 1 × 10(4) bacteria/mL in a field-friendly test strip format.
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Affiliation(s)
- Oscar R. Miranda
- Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Xiaoning Li
- Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Limary Garcia-Gonzalez
- Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931
| | - Zheng-Jiang Zhu
- Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Bo Yan
- Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Uwe H. F. Bunz
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332
| | - Vincent M. Rotello
- Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, Massachusetts 01003
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Smietana M, Bock WJ, Mikulic P, Ng A, Chinnappan R, Zourob M. Detection of bacteria using bacteriophages as recognition elements immobilized on long-period fiber gratings. Opt Express 2011; 19:7971-8. [PMID: 21643046 DOI: 10.1364/oe.19.007971] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The paper presents for the first time a study of long-period gratings (LPGs) applied for label-free detection of specific bacteria using physically adsorbed bacteriophages. For the purposes of the experiment a number of highly sensitive LPGs working at the turning point of phase matching curve was fabricated in SMF28 fiber using UV exposure. We show that the device allows for real-time monitoring of phenomena taking place on the sensor's surface, including phage-bacteria interactions. For the applied conditions a resonance wavelength shift of ~1.3 nm induced by bacteria binding was observed.
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Affiliation(s)
- Mateusz Smietana
- Centre de recherche en photonique, Université du Québec en Outaouais, Gatineau, QC, Canada.
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Beier BD, Quivey RG, Berger AJ. Identification of different bacterial species in biofilms using confocal Raman microscopy. J Biomed Opt 2010; 15:066001. [PMID: 21198175 PMCID: PMC3014224 DOI: 10.1117/1.3505010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 09/01/2010] [Accepted: 09/03/2010] [Indexed: 05/21/2023]
Abstract
Confocal Raman microspectroscopy is used to discriminate between different species of bacteria grown in biofilms. Tests are performed using two bacterial species, Streptococcus sanguinis and Streptococcus mutans, which are major components of oral plaque and of particular interest due to their association with healthy and cariogenic plaque, respectively. Dehydrated biofilms of these species are studied as a simplified model of dental plaque. A prediction model based on principal component analysis and logistic regression is calibrated using pure biofilms of each species and validated on pure biofilms grown months later, achieving 96% accuracy in prospective classification. When biofilms of the two species are partially mixed together, Raman-based identifications are achieved within ∼2 μm of the boundaries between species with 97% accuracy. This combination of spatial resolution and predication accuracy should be suitable for forming images of species distributions within intact two-species biofilms.
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Affiliation(s)
- Brooke D Beier
- University of Rochester, The Institute of Optics, Wilmot Building, Rochester, NY14627, USA
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Bae E, Bai N, Aroonnual A, Robinson JP, Bhunia AK, Hirleman ED. Modeling light propagation through bacterial colonies and its correlation with forward scattering patterns. J Biomed Opt 2010; 15:045001. [PMID: 20799796 DOI: 10.1117/1.3463003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Bacterial colonies play an important role in the isolation and identification of bacterial species, and plating on a petri dish is still regarded as the gold standard for confirming the cause of an outbreak situation. A bacterial colony consists of millions of densely packed individual bacteria along with matrices such as extracellular materials. When a laser is directed through a colony, complicated structures encode their characteristic signatures, which results in unique forward scattering patterns. We investigate the connection between the morphological parameters of a bacterial colony and corresponding forward scattering patterns to understand bacterial growth morphology. A colony elevation is modeled with a Gaussian profile, which is defined with two critical parameters: center thickness and diameter. Then, applying the scalar diffraction theory, we compute an amplitude modulation via light attenuation from multiple layers of bacteria while a phase modulation is computed from the colony profile. Computational results indicate that center thickness plays a critical role in the total number of diffraction rings while the magnitude of the slope of a colony determines the maximum diffraction angle. Experimental validation is performed by capturing the scattering patterns, monitoring colony diameters via phase contrast microscope, and acquiring the colony profiles via confocal displacement meter.
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Affiliation(s)
- Euiwon Bae
- Purdue University, School of Mechanical Engineering, West Lafayette, Indiana 47906, USA.
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