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Yakdhane E, Tőzsér D, Haykir O, Yakdhane A, Labidi S, Kiskó G, Baranyai L. Recognition of environmental contaminant and pathogenic bacteria by means of redox potential methodology. MethodsX 2024; 13:102811. [PMID: 39022177 PMCID: PMC11253682 DOI: 10.1016/j.mex.2024.102811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 06/18/2024] [Indexed: 07/20/2024] Open
Abstract
The time-consuming nature of culturing methods has urged the exploration of rapid modern technologies. One promising alternative utilizes redox potential, which describes the oxidative changes within complex media, indicating oxygen and nutrient consumption, as well as the production of reduced substances in the investigated biological system. Redox potential measurement can detect microbial activity within 16 h, what is significantly faster than the minimum 24 h incubation time of the reference plate counting technique. The redox potential based method can be specific with selective media, but bacterial strains have unique kinetic pattern as well. The proposed method suggests evaluation of the curve shape for the differentiation of environmental contaminant and pathogenic microbial strains. Six bacterial species were used in validation (Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Listeria innocua, Listeria monocytogenes, and Listeria ivanovii). Descriptive parameters reached 98.2 % accuracy and Gompertz model achieved 91.6 % accuracy in classification of the selected 6 bacteria species.•Mathematical model (Gompertz function) and first order descriptive parameters are suggested to describe the specific shape of redox potential curves, while Support Vector Machine (SVM) is recommended for classification.•Due to the concentration dependent time to detection (TTD), pre-processing applies standardization according to the inflection point time.
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Affiliation(s)
- Eya Yakdhane
- Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences (MATE), Budapest 1118, Hungary
| | - Dóra Tőzsér
- Department of Food Hygiene, University of Veterinary Medicine, H-1078 Budapest, István u. 2., Hungary
| | - Oktay Haykir
- Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences (MATE), Budapest 1118, Hungary
| | - Asma Yakdhane
- Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences (MATE), Budapest 1118, Hungary
| | - Sabrine Labidi
- Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences (MATE), Budapest 1118, Hungary
| | - Gabriella Kiskó
- Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences (MATE), Budapest 1118, Hungary
| | - László Baranyai
- Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences (MATE), Budapest 1118, Hungary
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Velema WA. Exploring antibiotic resistance with chemical tools. Chem Commun (Camb) 2023; 59:6148-6158. [PMID: 37039397 PMCID: PMC10194278 DOI: 10.1039/d3cc00759f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/05/2023] [Indexed: 04/08/2023]
Abstract
Antibiotic resistance is an enormous problem that is accountable for over a million deaths annually, with numbers expected to significantly increase over the coming decades. Although some of the underlying causes leading up to antibiotic resistance are well understood, many of the molecular processes involved remain elusive. To better appreciate at a molecular level how resistance emerges, customized chemical biology tools can offer a solution. This Feature Article attempts to provide an overview of the wide variety of tools that have been developed over the last decade, by highlighting some of the more illustrative examples. These include the use of fluorescent, photoaffinity and activatable antibiotics and bacterial components to start to unravel the molecular mechanisms involved in resistance. The antibiotic crisis is an eminent global threat and requires the continuous development of creative chemical tools to dissect and ultimately counteract resistance.
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Affiliation(s)
- Willem A Velema
- Institute for Molecules and Materials, Radboud University Nijmegen, The Netherlands, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
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Alenkaer LK, Pedersen L, Szecsi PB, Bjerrum PJ. Evaluation of the sysmex UF-5000 fluorescence flow cytometer as a screening platform for ruling out urinary tract infections in elderly patients presenting at the Emergency Department. Scandinavian Journal of Clinical and Laboratory Investigation 2021; 81:379-384. [PMID: 34237238 DOI: 10.1080/00365513.2021.1929441] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In this study, we evaluated the performance of the flow cytometer-based Sysmex UF-5000 automated urine analyzer as a screening tool for ruling out urinary tract infections in elderly patients presenting at the emergency department. A total of 1119 unselected patient samples (including 544 samples from elderly patients) submitted for urine culture were included in this study. Samples were measured on UF-5000 and dipsticks and the results were compared with interpretation of culture results, which is the gold standard. We obtained a diagnostic sensitivity of 99% and specificity of 51% with a low rate of false negatives (0.2%) and a negative predictive value of 99% at 108 colony forming bacteria/L (CFB/L). A bacterial count ≥ 50x106/L or yeast like cells ≥ 25x106/L was used as the cutoff value. At this cutoff value, 30% of the urine cultures would have been redundant. This resulted in 35% false positive samples, mainly due to particle contamination or nongrowing bacteria. In comparison, at best, the dipsticks have a diagnostic sensitivity of 89%, a specificity of 52% and a negative predictive value of 92% at 108 CFB/L.
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Affiliation(s)
- Lasse Krogh Alenkaer
- Department of Clinical Biochemistry, University of Copenhagen, Holbaek Hospital, Holbaek, Denmark
| | - Lise Pedersen
- Department of Clinical Biochemistry, University of Copenhagen, Holbaek Hospital, Holbaek, Denmark
| | - Pal Bela Szecsi
- Department of Clinical Biochemistry, University of Copenhagen, Holbaek Hospital, Holbaek, Denmark
| | - Poul Jannik Bjerrum
- Department of Clinical Biochemistry, University of Copenhagen, Holbaek Hospital, Holbaek, Denmark
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In Memoriam: Marvin A. Van Dilla. Cytometry A 2020; 97:1198-1201. [DOI: 10.1002/cyto.a.24205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 07/27/2020] [Indexed: 11/11/2022]
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Liu R, Chu CH, Wang N, Ozkaya-Ahmadov T, Civelekoglu O, Lee D, Arifuzzman AKM, Sarioglu AF. Combinatorial Immunophenotyping of Cell Populations with an Electronic Antibody Microarray. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1904732. [PMID: 31631578 DOI: 10.1002/smll.201904732] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/05/2019] [Indexed: 06/10/2023]
Abstract
Immunophenotyping is widely used to characterize cell populations in basic research and to diagnose diseases from surface biomarkers in the clinic. This process usually requires complex instruments such as flow cytometers or fluorescence microscopes, which are typically housed in centralized laboratories. Microfluidics are combined with an integrated electrical sensor network to create an antibody microarray for label-free cell immunophenotyping against multiple antigens. The device works by fractionating the sample via capturing target subpopulations in an array of microfluidic chambers functionalized against different antigens and by electrically quantifying the cell capture statistics through a network of code-multiplexed electrical sensors. Through a combinatorial arrangement of antibody sequences along different microfluidic paths, the device can measure the prevalence of different cell subpopulations in a sample from computational analysis of the electrical output signal. The device performance is characterized by analyzing heterogeneous samples of mixed tumor cell populations and then the technique is applied to determine leukocyte subpopulations in blood samples and the results are validated against complete blood cell count and flow cytometry results. Label-free immunophenotyping of cell populations against multiple targets on a disposable electronic chip presents opportunities in global health and telemedicine applications for cell-based diagnostics and health monitoring.
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Affiliation(s)
- Ruxiu Liu
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Chia-Heng Chu
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ningquan Wang
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Tevhide Ozkaya-Ahmadov
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ozgun Civelekoglu
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Dohwan Lee
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - A K M Arifuzzman
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - A Fatih Sarioglu
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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Millán-Lou MI, García-Lechuz JM, Ruiz-Andrés MA, López C, Aldea MJ, Revillo MJ, Rezusta A. Validation and Search of the Ideal Cut-Off of the Sysmex UF-1000i ® Flow Cytometer for the Diagnosis of Urinary Tract Infection in a Tertiary Hospital in Spain. Front Med (Lausanne) 2018; 5:92. [PMID: 29686988 PMCID: PMC5900046 DOI: 10.3389/fmed.2018.00092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/23/2018] [Indexed: 11/30/2022] Open
Abstract
Urinary tract infections (UTI) are one of the most prevalent infections. A rapid and reliable screening method is useful to screen out negative samples. The objective of this study was to validate the Sysmex flow cytometer UF-1000i by evaluating its accuracy, linearity and carry-over; and define an optimal cut-off value to be used in routine practice in our hospital. For the validation of the UF-1000i cytometer, precision, linearity and carry-over were studied in samples with different counts of bacteria, leukocytes and erythrocytes. Between March and June 2016, urine samples were tested in the Clinical Microbiology Laboratory at University Miguel Servet Hospital, in Spain. Samples were analyzed with the Sysmex UF-1000i cytometer, and cultured. Growth of ≥105 CFUs/mL was considered positive. The validation study reveals that the precision in all the variables is acceptable; that there is a good linearity in the dilutions performed, obtaining values almost identical to those theoretically expected; and for the carry-over has practically null values. A total of 1,220 urine specimens were included, of which 213 (17.4%) were culture positive. The optimal cut-off point of the bacteria–leukocyte combination was 138.8 bacteria or 119.8 leukocytes with an S and E of 95.3 and 70.4%, respectively. The UF-1000i cytometer is a valuable method to screen urine samples to effectively rule out UTI and, may contribute to the reduction of unnecessary urine cultures.
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Affiliation(s)
- María I Millán-Lou
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain.,Instituto de Investigación Sanitaria Aragón (IIS Aragón), Zaragoza, Spain
| | - Juan M García-Lechuz
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain
| | - María A Ruiz-Andrés
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain
| | - Concepción López
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain
| | - María J Aldea
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain
| | - María J Revillo
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain
| | - Antonio Rezusta
- Servicio de Microbiología, Hospital Universitario Miguel-Servet, Zaragoza, Spain.,Instituto de Investigación Sanitaria Aragón (IIS Aragón), Zaragoza, Spain.,Universidad de Zaragoza, Zaragoza, Spain
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Béland P, Krupin O, Berini P. Selective detection of bacteria in urine with a long-range surface plasmon waveguide biosensor. BIOMEDICAL OPTICS EXPRESS 2015; 6:2908-22. [PMID: 26309755 PMCID: PMC4541519 DOI: 10.1364/boe.6.002908] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 07/08/2015] [Accepted: 07/12/2015] [Indexed: 05/14/2023]
Abstract
Experimentation demonstrates long-range surface plasmon polariton waveguides as a useful biosensor to selectively detect gram negative or gram positive bacteria in human urine having a low concentration of constituents. The biosensor can detect bacteria at concentrations of 10(5) CFU/ml, the internationally recommended threshold for diagnostic of urinary tract infection. Using a negative control urine solution of bacterial concentration 1000☓ higher than the targeted bacteria, we obtain a ratio of 5.4 for the positive to negative signals.
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Affiliation(s)
- Paul Béland
- Dept. of Biomedical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, K1N 6N5, Canada
| | - Oleksiy Krupin
- Dept. of Biological and Chemical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, K1N 6N5, Canada
| | - Pierre Berini
- School of Electrical Engineering and Computer Science, University of Ottawa, 800 King Edward Avenue, Ottawa, K1N 6N5, Canada
- Dept. of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, K1N 6N5, Canada
- Centre for Research in Photonics, University of Ottawa, 800 King Edward Avenue, Ottawa, K1N 6N5, Canada
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8
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Rüger M, Ackermann M, Reichl U. Species-specific viability analysis of Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus in mixed culture by flow cytometry. BMC Microbiol 2014; 14:56. [PMID: 24606608 PMCID: PMC3995885 DOI: 10.1186/1471-2180-14-56] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 02/25/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Bacterial species coexist commonly in mixed communities, for instance those occurring in microbial infections of humans. Interspecies effects contribute to alterations in composition of communities with respect to species and thus, to the course and severity of infection. Therefore, knowledge concerning growth and viability of single species in medically-relevant mixed communities is of high interest to resolve complexity of interspecies dynamics and to support development of treatment strategies. In this study, a flow cytometric method was established to assess the species-specific viability in defined three-species mixed cultures. The method enables the characterization of viability of Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus, which are relevant to lung infections of Cystic Fibrosis (CF) patients. The method combines fluorescence detection by antibody and lectin labeling with viability fluorescence staining using SYBRGreen I and propidium iodide. In addition, species-specific cell enumeration analysis using quantitative terminal restriction fragment length polymorphisms (qT-RFLP) was used to monitor the growth dynamics. Finally, to investigate the impact of substrate availability on growth and viability, concentrations of main substrates and metabolites released were determined. RESULTS For each species, the time course of growth and viability during mixed culture cultivations was obtained by using qT-RFLP analysis in combination with flow cytometry. Comparison between mixed and pure cultures revealed for every species differences in growth properties, e.g. enhanced growth of P. aeruginosa in mixed culture. Differences were also observed for B. cepacia and S. aureus in the time course of viability, e.g. an early and drastic reduction of viability of S. aureus in mixed culture. Overall, P. aeruginosa clearly dominated the mixed culture with regard to obtained cell concentrations. CONCLUSIONS In combination with qT-RFLP analysis, the methods enabled monitoring of species-specific cell concentrations and viability during co-cultivation of theses strains. Experimental findings suggest that the predominance of P. aeruginosa over B. cepacia and S. aureus in mixed culture under the chosen cultivation conditions is promoted by more efficient substrate consumption of P. aeruginosa, and antagonistic interspecies effects induced by P. aeruginosa.
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Affiliation(s)
- Marc Rüger
- Chair of Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Mandy Ackermann
- Chair of Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
| | - Udo Reichl
- Chair of Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany
- Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
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9
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Rüger M, Bensch G, Tüngler R, Reichl U. A flow cytometric method for viability assessment of Staphylococcus aureus and Burkholderia cepacia in mixed culture. Cytometry A 2012; 81:1055-66. [PMID: 23081865 DOI: 10.1002/cyto.a.22219] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 09/07/2012] [Accepted: 09/20/2012] [Indexed: 11/06/2022]
Abstract
Mixed bacterial communities are commonly encountered in microbial infections of humans. Knowledge on the composition of species and viability of each species in these communities allows for a detailed description of the complexity of interspecies dynamics and contributes to the assessment of the severity of infections. Several assays exist for quantification of specific species in mixed communities, including analysis of quantitative terminal restriction fragment length polymorphisms. While this method allows for species-specific cell enumeration, it cannot provide viability data. In this study, flow cytometry was applied to assess the viability of Staphylococcus aureus and Burkholderia cepacia in mixed culture by membrane integrity analysis using SYBR® Green I and propidium iodide staining. Both bacteria are relevant to pulmonary infections of cystic fibrosis patients. Fluorescence staining was optimized separately for each species in pure culture due to differences between species in cell wall structure and metabolic capabilities. To determine viability of species in mixed culture, a protocol was established as a compromise between optimum conditions determined before for pure cultures. This protocol allowed the detection of viable and dead cells of both species, exhibiting an intact and a permeabilized membrane, respectively. To discriminate between S. aureus and B. cepacia, the protocol was combined with Gram-specific fluorescent staining using wheat germ agglutinin. The established three-color staining method was successfully tested for viability determination of S. aureus and B. cepacia in mixed culture cultivations. In addition, growth of both species was monitored by quantitative terminal restriction fragment length polymorphisms. The obtained data revealed alterations in viability during cultivations for different growth phases and suggest interspecies effects in mixed culture. Overall, this method allows for rapid simultaneous Gram-differentiation and viability assessment of bacterial mixed cultures and is therefore suitable for the analysis of dynamics of mixed communities of medical, environmental, and biotechnological relevance.
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Affiliation(s)
- Marc Rüger
- Chair of Bioprocess Engineering, Otto von Guericke University, Magdeburg, Germany.
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Corbitt TS, Zhou Z, Tang Y, Graves SW, Whitten DG. Rapid evaluation of the antibacterial activity of arylene-ethynylene compounds. ACS APPLIED MATERIALS & INTERFACES 2011; 3:2938-2943. [PMID: 21714540 DOI: 10.1021/am200277c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A series of oligo(arylene-ethynylene) (1-3 repeat units) compounds functionalized with quaternary ammonium groups was screened for their antibacterial activity in the dark and with activation by long-wavelength (365 nm) UV irradiation. Several of these compounds have effective bactericidal activity (>99.9% killing) at concentrations between 0.01 and 10 μg/mL. Our approach uses flow cytometry to rapidly screen and evaluate the susceptibility of bacterial populations. The rapidity, high information content, and accuracy of this approach make it an extremely valuable method for the study of antibacterial compounds.
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Affiliation(s)
- Thomas S Corbitt
- Center for Biomedical Engineering, Department of Chemical & Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131, United States
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Wang J, Zhang Y, Xu D, Shao W, Lu Y. Evaluation of the Sysmex UF-1000i for the diagnosis of urinary tract infection. Am J Clin Pathol 2010; 133:577-82. [PMID: 20231611 DOI: 10.1309/ajcp1gt2jxocqbcz] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Diagnosis of urinary tract infection (UTI) is primarily done by microbiologic culture, which is time-consuming and can produce false-positives and false-negatives. Flow cytometry allows for rapid screening of many samples and eliminates culturing. We analyzed the Sysmex UF-1000i (TOA Medical Electronics, Kobe, Japan) for accuracy in identifying RBCs and WBCs, casts, bacteria, and epithelia. We also evaluated its precision, linear estimation of results, carryover contamination rate, and anti-interference. UF-1000i agreement with manual counting was approximately 95% for RBCs and WBCs, epithelia, and casts. Its coefficient of variation for bacteria ranged from 4.7% to 15.2%. UF-1000i screening for UTIs exhibited great sensitivity (97%), specificity (79%), positive predictive value (70%), negative predictive value (99%), and accuracy (85%). The negative predictive value remained high even with complex UTI samples. The Sysmex UF-1000i shows great promise in excluding more than 50% of true-negative samples, improving detection efficiency, and reducing laboratory costs.
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Orth R, O'Brien-Simpson N, Dashper S, Walsh K, Reynolds E. An efficient method for enumerating oral spirochetes using flow cytometry. J Microbiol Methods 2009; 80:123-8. [PMID: 19932718 DOI: 10.1016/j.mimet.2009.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 11/11/2009] [Accepted: 11/16/2009] [Indexed: 10/20/2022]
Abstract
Spirochetes, such as Treponema denticola, are thin walled, helical, motile bacteria. They are notoriously difficult to enumerate due to their thinness and the difficulties associated with culturing them. Here we have developed a modified oral bacterial growth medium (OBGM) that significantly improves the cultivation of T. denticola compared with a previously published growth medium. Three methods for the enumeration of T. denticola, semi-solid growth medium colony-forming unit (CFU) counts, DNA analysis and flow cytometry, are described and compared. Enumeration of T. denticola using the semi-solid agar method resulted in a positive linear relationship with absorbance of the culture (R(2)=0.9423). However, the semi-solid agar method was found to consistently underestimate (by 50 fold) the T. denticola cell density compared to previously published data. DNA analysis of T. denticola cultures reliably and consistently resulted in a positive linear relationship with absorbance (R(2)=0.9360), giving a calculated cell density of 6.9 x 10(8)cells/mL at an absorbance of 0.2 at 650 nm. Flow cytometry was also found to result in a positive linear relationship with absorbance (R(2)=0.9874), giving a calculated cell density of 6.6 x 10(8)cells/mL at an absorbance of 0.2 at 650 nm. In comparing all of these enumeration methods, the flow cytometry method was found to have distinct advantages, as it is accurate, rapid, and could distinguish between live and dead bacteria. Thus flow cytometry is a recommended means for the rapid and reliable enumeration of viable spirochetes from culture.
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Affiliation(s)
- Rebecca Orth
- Cooperative Research Centre for Oral Health Science, Melbourne Dental School, Australia
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13
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Sample preparation module for bacterial lysis and isolation of DNA from human urine. Biomed Microdevices 2009; 11:671-678. [PMID: 19130239 DOI: 10.1007/s10544-008-9277-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Silica impregnated polymer monolithic columns may provide a simple method for lysing and extracting DNA from bacteria inside of microfluidic chips. Here we use Escherichia coli as a test organism for a point of care thermoplastic microfluidic module designed to take in a urine sample, mix it with lysis buffer, and perform a hybrid chemical/mechanical lysis and solid phase extraction of nucleic acids from the sample. To demonstrate proof-of-concept, we doped human hematuric urine samples with E. coli at concentrations ranging from 10(1)-10(5) colony-forming units/mL (CFU/mL) to simulate patient samples. We then performed on-chip lysis and DNA extraction. The bacterial DNA was amplified using real-time PCR demonstrating lysis and isolation down to 10(1) CFU/mL. Results were comparable to a commercial kit at higher concentrations and performed better at recovering DNA at lower concentrations.
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Marcotte L, Kegelaer G, Sandt C, Barbeau J, Lafleur M. An alternative infrared spectroscopy assay for the quantification of polysaccharides in bacterial samples. Anal Biochem 2007; 361:7-14. [PMID: 17169320 DOI: 10.1016/j.ab.2006.11.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 10/23/2006] [Accepted: 11/03/2006] [Indexed: 11/29/2022]
Abstract
The ability of bacteria to produce extracellular polysaccharides has been regarded as an indication of biofilm-forming capacity. Therefore, the determination of the sugar content in bacterial samples becomes a significant parameter. The colorimetric methods currently used are rather sensitive to the nature of the sugars and therefore require knowledge of the sugar types present in the samples. Unfortunately, the types of sugars present in bacteria are generally unknown and often composed of a complex mixture. In this article, we propose an alternative method based on Fourier transform infrared (FTIR) spectroscopy for the estimation of the total sugar content in bacterial samples. The method is based on a systematic treatment of FTIR spectra obtained from dried bacteria samples. It is assumed that the total sugar amount can be estimated from the area of characteristic bands between 970 and 1182 cm(-1). In parallel, the amide II band (1560-1530 cm(-1)) associated with proteins, or the C-H stretching region (2820-3020 cm(-1)) associated with the biomass, can be used for normalization purposes. Therefore, the ratio of the band area in the sugar window over that of the amide II or C-H stretching can be used to report the sugar content in bacterial samples. This method has been validated on model bacterial mixtures containing sugars, proteins, and DNA. Results with real bacterial samples are also provided and show conclusively that increased sugar contents in biofilms can be identified. The proposed FTIR approach requires minimal sample preparation and a single acquisition, is rapid, and may be applied to any kind of bacterial growth.
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Affiliation(s)
- Lucie Marcotte
- Department of Chemistry, University of Montreal, Montreal, Que., Canada H3C 3J7
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15
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Alcon A, Santos VE, Casas J, Garcı́a-Ochoa F. Use of flow cytometry for growth structured kinetic model development. Enzyme Microb Technol 2004. [DOI: 10.1016/j.enzmictec.2003.10.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Müler S, Lösche A, Mertingk H, Beisker W, Babel W. Flow cytometric monitoring ofRhodococcus erythropolisandOchrobactrum anthropiin a mixed culture. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/abio.370200306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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Herrmann C, Babel WT, Lösche A, Müller S, Bley S. Flow cytometric discrimination betweenAcinetobacter calcoaceticus69-V andAlcaligenes eutrophusJMP134 by fluorescently labelled rRNA-targeted oligonucleotide probes and DNA staining. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/abio.370170103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Grötz KA, Al-Nawas B, Duschner H. Correlating micromorphology of the pulpal odontoblast seam using confocal laser scanning microscopy and dark field microscopy. Clin Oral Investig 2003; 7:59-61. [PMID: 12673441 DOI: 10.1007/s00784-002-0190-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2002] [Accepted: 11/11/2001] [Indexed: 11/28/2022]
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Stopa PJ, Mastromanolis SA. The use of blue-excitable nucleic-acid dyes for the detection of bacteria in well water using a simple field fluorometer and a flow cytometer. J Microbiol Methods 2001; 45:143-53. [PMID: 11348672 DOI: 10.1016/s0167-7012(01)00252-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The blue-excitable nucleic acid dyes Coriphosphine O (CPO), YOYO-1, and YOPRO-1 were evaluated to rapidly detect the presence of bacteria in well water samples using a simple field fluorometer (Turner Designs, Sunnyvale, CA, Model 10-AU-005) and a tabletop flow cytometer (Coulter Epics XL). The dyes were first titrated on the Turner Designs Model 10-AU field fluorometer with log-fold dilutions of Esherichia coli, since this organism is the indicator organism for water contamination. A detection limit of 10(4) Colony Forming Units per ml (CFU/ml) was established for YOPRO-1 and 10(5) CFU/ml for YOYO-1. The detection limit with CPO was determined to be 10(7) CFU/ml due to the high background fluorescence of the dye. The dyes were also evaluated with ragweed pollen to gauge the effect of a biological interferent. Ten well-water samples were subsequently analyzed using the technique. The results showed that only YOYO-1 correctly detected all the samples that were positive according to the reference laboratory. YOPRO-1 correctly detected only one of four positive samples. Analysis with the CPO dye was inconclusive due to high background fluorescence. The samples were then subjected to analysis on the flow cytometer. Results obtained with YOYO-1 compared well to those obtained on the fluorometer and by the reference techniques. YOPRO-1 performed better on the flow cytometer than with the simple fluorometer, correctly detecting three of four positive samples. Although the CPO results showed a very slight increase of green fluorescence with positive samples, they were largely indistinguishable from negative samples. This study suggests YOYO-1 could be useful with either a simple fluorometer or with a tabletop flow cytometer in screening water samples for the presence of bacterial contamination.
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Affiliation(s)
- P J Stopa
- The US Army Edgewood Chemical and Biological Center, Engineering Directorate, 5183 Blackhawk Road, AMSSB-REN-E-MC E3549, Aberdeen Proving Ground, MD 21010-5424, USA.
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20
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Boeck G. Current status of flow cytometry in cell and molecular biology. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 204:239-98. [PMID: 11243596 DOI: 10.1016/s0074-7696(01)04006-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This review summarizes recent developments in flow cytometry (FC). It gives an overview of techniques currently available, in terms of apparatus and sample handling, a guide to evaluating applications, an overview of dyes and staining methods, an introduction to internet resources, and a broad listing of classic references and reviews in various fields of interest, as well as some recent interesting articles.
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Affiliation(s)
- G Boeck
- Institute for General and Experimental Pathology, University Innsbruck, Medical School, Austria
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21
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Walberg M, Steen HB. Flow cytometric monitoring of bacterial susceptibility to antibiotics. Methods Cell Biol 2001; 64:553-66. [PMID: 11070855 DOI: 10.1016/s0091-679x(01)64029-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- M Walberg
- Institute of Medical Microbiology, National Hospital, University of Oslo, Norway
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22
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Affiliation(s)
- S A Sincock
- Purdue Cytometry Laboratories, Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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23
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ENDO H, TSUKATANI H, HAYASHI T, MURAMATSU H. Flow Cytometry for Rapid Detection of Ampicillin Activity Using Bacterial Susceptibility and its Application to Aquaculture. ELECTROCHEMISTRY 2000. [DOI: 10.5796/electrochemistry.68.862] [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] Open
Affiliation(s)
- Hideaki ENDO
- Department of Food Science and Technology, Tokyo University of Fisheries
| | - Hitomi TSUKATANI
- Department of Food Science and Technology, Tokyo University of Fisheries
| | - Tetsuhito HAYASHI
- Department of Food Science and Technology, Tokyo University of Fisheries
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24
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Larson EJ, Hakovirta JR, Cai H, Jett JH, Burde S, Keller RA, Marrone BL. Rapid DNA fingerprinting of pathogens by flow cytometry. CYTOMETRY 2000; 41:203-8. [PMID: 11042617 DOI: 10.1002/1097-0320(20001101)41:3<203::aid-cyto7>3.0.co;2-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND A new method for rapid discrimination among bacterial strains based on DNA fragment sizing by flow cytometry is presented. This revolutionary approach combines the reproducibility and reliability of restriction fragment length polymorphism (RFLP) analysis with the speed and sensitivity of flow cytometry. METHODS Bacterial genomic DNA was isolated and digested with a rare-cutting restriction endonuclease. The resulting fragments were stained stoichiometrically with PicoGreen dye and introduced into an ultrasensitive flow cytometer. A histogram of burst sizes from the restriction fragments (linearly related to fragment length in base pairs) resulted in a DNA fingerprint that was used to distinguish among different bacterial strains. RESULTS Five different strains of gram-negative Escherichia coli and six different strains of gram-positive Staphylococcus aureus were distinguished by analyzing their restriction fragments with DNA fragment sizing by flow cytometry. Fragment distribution analyses of extracted DNA were approximately 100 times faster and approximately 200,000 times more sensitive than pulsed-field gel electrophoresis (PFGE). When sample preparation time is included, the total DNA fragment analysis time was approximately 8 h by flow cytometry and approximately 24 h by PFGE. CONCLUSIONS DNA fragment sizing by flow cytometry is a fast and reliable technique that can be applied to the discrimination among species and strains of human pathogens. Unlike some polymerase chain reaction (PCR)-based methods, sequence information about the bacterial strains is not required, allowing the detection of unknown, newly emerged, or unanticipated strains.
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Affiliation(s)
- E J Larson
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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25
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Abstract
The application of flow cytometry to microorganisms is as old as the technique itself, but it has historically been underexploited for microbial applications. This is now being reversed and microbiologists are ideally placed to benefit from recent technological advances. While earlier papers demonstrated the use of flow cytometry for studies of viability and taxonomy, recent developments in bioinformatics and reporter gene technologies are leading to novel applications in microbiology. Variants of green fluorescent protein have been used for the study of conditional microbial gene regulation in medically important host-pathogen interactions and fluorescence-activated cell sorting is being applied to the isolation of novel mutants in directed evolution studies. This paper reviews the reasons for the delay in the application of flow cytometry to microbial problems, the range of applications, and their limitations and considers the progress made in developing new strategies for use in microbiological investigations.
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Affiliation(s)
- M K Winson
- Institute of Biological Sciences, University of Wales, Aberystwyth, SY23 3DD, United Kingdom
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26
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Zubkov MV, Fuchs BM, Eilers H, Burkill PH, Amann R. Determination of total protein content of bacterial cells by SYPRO staining and flow cytometry. Appl Environ Microbiol 1999; 65:3251-7. [PMID: 10388732 PMCID: PMC91485 DOI: 10.1128/aem.65.7.3251-3257.1999] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An assay has been developed for measuring protein biomass of marine planktonic bacteria by flow cytometry. The method was calibrated by using five species of Bacteria (an Arcobacter sp., a Cytophaga sp., an Oceanospirillum sp., a Pseudoalteromonas sp., and a Vibrio sp.) recently isolated from seawater samples and grown in culture at different temperatures. The intensity of SYPRO-protein fluorescence of these bacteria strongly correlated with their total protein content, measured by the bicinchoninic acid method to be in the range of 60 to 330 fg of protein cell-1 (r2 = 0.93, n = 34). According to the calibration, the mean biomass of planktonic bacteria from the North Sea in August 1998 was 24 fg of protein cell-1.
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Affiliation(s)
- M V Zubkov
- Plymouth Marine Laboratory, Plymouth PL1 3DH, United Kingdom.
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27
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Walberg M, Gaustad P, Steen HB. Uptake kinetics of nucleic acid targeting dyes in S. aureus, E. faecalis and B. cereus: a flow cytometric study. J Microbiol Methods 1999; 35:167-76. [PMID: 10192050 DOI: 10.1016/s0167-7012(98)00118-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
For flow cytometry-based detection as well as susceptibility testing and counting, staining of the bacterial cells is essential. In an attempt to develop rapid preparatory procedures for nucleic acid staining of wild type Gram positive bacteria, the uptake of fluorescent dyes in viable S. aureus, E. faecalis, and B. cereus cells was studied by flow cytometry under conditions intended to block probe efflux and increase cell wall permeability. The aim of the study was to develop procedures which allow rapid nucleic acid staining independent of fixation, since ethanol fixation is time-consuming and may mask phenomena associated with viability and lead to uncontrolled loss and aggregation of cells. The dye uptake was measured repeatedly after treating cells with metabolic inhibitors in order to block probe efflux, or cold shock (0 degree C) to increase permeability. The probes used were mithramycin (Mi), ethidium bromide (EB), DAPI, Hoechst 33342 and Hoechst 33258. None of the procedures facilitated uptake of the dyes to a level similar to that obtained in fixed control cells in all of the species. After metabolic inhibition of B. cereus cells, DAPI and Hoechst fluorescence increased to a level similar to or above that found in fixed cells, indicating that the uptake of these dyes is limited by energy-dependent efflux. A similar increase of DAPI fluorescence was observed after cold shock suggesting the uptake of this dye to be limited also by permeability in B. cereus. The Mi and EB fluorescence increased to the level of the fixed control cells under all conditions tested, suggesting free probe influx in this species. Generally, probe uptake in S. aureus and E. faecalis was lower than in B. cereus cells, and no permeabilizing effect of cold shock was observed. In some experiments the fluorescence exceeded that of ethanol fixed control cells, indicating that the fixation may cause conformational changes in DNA.
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Affiliation(s)
- M Walberg
- Institute of Microbiology, Rikshospitalet, Oslo, Norway.
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28
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Sincock SA, Kulaga H, Cain M, Anderson P, Stopa PJ. Applications of flow cytometry for the detection and characterization of biological aerosols. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1520-6521(1999)3:4/5<291::aid-fact8>3.0.co;2-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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29
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Bresler V, Montgomery WL, Fishelson L, Pollak PE. Gigantism in a bacterium, Epulopiscium fishelsoni, correlates with complex patterns in arrangement, quantity, and segregation of DNA. J Bacteriol 1998; 180:5601-11. [PMID: 9791108 PMCID: PMC107617 DOI: 10.1128/jb.180.21.5601-5611.1998] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/1998] [Accepted: 09/01/1998] [Indexed: 11/20/2022] Open
Abstract
Epulopiscium fishelsoni, gut symbiont of the brown surgeonfish (Acanthurus nigrofuscus) in the Red Sea, attains a larger size than any other eubacterium, varies 10- to 20-fold in length (and >2, 000-fold in volume), and undergoes a complex daily life cycle. In early morning, nucleoids contain highly condensed DNA in elongate, chromosome-like structures which are physically separated from the general cytoplasm. Cell division involves production of two (rarely three) nucleoids within a cell, deposition of cell walls around expanded nucleoids, and emergence of daughter cells from the parent cell. Fluorescence measurements of DNA, RNA, and other cell components indicate the following. DNA quantity is proportional to cell volume over cell lengths of approximately 30 micrometers to >500 micrometers. For cells of a given size, nucleoids of cells with two nucleoids (binucleoid) contain approximately equal amounts of DNA. And each nucleoid of a binucleoid cell contains one-half the DNA of the single nucleoid in a uninucleoid cell of the same size. The life cycle involves approximately equal subdivision of DNA among daughter cells, formation of apical caps of condensed DNA from previously decondensed and diffusely distributed DNA, and "pinching" of DNA near the middle of the cell in the absence of new wall formation. Mechanisms underlying these patterns remain unclear, but formation of daughter nucleoids and cells occurs both during diurnal periods of host feeding and bacterial cell growth and during nocturnal periods of host inactivity when mean bacterial cell size declines.
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Affiliation(s)
- V Bresler
- Institute for Nature Conservation Research, G. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel
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30
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Determination of the biomasses of small bacteria at low concentrations in a mixture of species with forward light scatter measurements by flow cytometry. Appl Environ Microbiol 1998; 64:3900-9. [PMID: 9758817 PMCID: PMC106576 DOI: 10.1128/aem.64.10.3900-3909.1998] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The forward light scatter intensity of bacteria analyzed by flow cytometry varied with their dry mass, in accordance with theory. A standard curve was formulated with Rayleigh-Gans theory to accommodate cell shape and alignment. It was calibrated with an extinction-culture isolate of the small marine organism Cycloclasticus oligotrophus, for which dry weight was determined by CHN analysis and 14C-acetate incorporation. Increased light scatter intensity due to formaldehyde accumulation in preserved cells was included in the standard curve. When differences in the refractive indices of culture media and interspecies differences in the effects of preservation were taken into account, there was agreement between cell mass obtained by flow cytometry for various bacterial species and cell mass computed from Coulter Counter volume and buoyant density. This agreement validated the standard curve and supported the assumption that cells were aligned in the flow stream. Several subpopulations were resolved in a mixture of three species analyzed according to forward light scatter and DNA-bound DAPI (4', 6-diamidino-2-phenylindole) fluorescence intensity. The total biomass of the mixture was 340 &mgr;g/liter. The lowest value for mean dry mass, 0.027 +/- 0.008 pg/cell, was for the subpopulation of C. oligotrophus containing cells with a single chromosome. Calculations from measurements of dry mass, Coulter Counter volume, and buoyant density revealed that the dry weight of the isolate was 14 to 18% of its wet weight, compared to 30% for Escherichia coli. The method is suitable for cells with 0.005 to about 1.2 pg of dry weight at concentrations of as low as 10(3) cells/ml and offers a unique capability for determining biomass distributions in mixed bacterial populations.
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31
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Rapid preparation procedure for staining of exponentially growing P. vulgaris cells with ethidium bromide: a flow cytometry-based study of probe uptake under various conditions. J Microbiol Methods 1998. [DOI: 10.1016/s0167-7012(98)00072-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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32
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Abstract
Our understanding of microbial adaptations to diverse and threatening environments is limited by the assumption that the behavior of individual bacteria can be accurately determined by measuring the behavior of populations. Recent advances in gene expression reporter systems, fluorescence microscopy and flow cytometry allow microbiologists to explore the complex interactions between bacteria and their environment with single cell resolution. The application of these technologies has been particularly useful in systems, such as host-pathogen interactions, where genetic analysis is often cumbersome. Recently, flow cytometry is increasingly being applied to study host-pathogen interactions.
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Affiliation(s)
- R H Valdivia
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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33
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Gottfredsson M, Erlendsdóttir H, Sigfússon A, Gudmundsson S. Characteristics and dynamics of bacterial populations during postantibiotic effect determined by flow cytometry. Antimicrob Agents Chemother 1998; 42:1005-11. [PMID: 9593117 PMCID: PMC105733 DOI: 10.1128/aac.42.5.1005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Changes in bacterial ultrastructure after antibiotic exposure and during the postantibiotic effect (PAE) have been demonstrated by electron microscopy (EM). However, EM is qualitative and subject to individual interpretation. In contrast, flow cytometry gives qualitative and quantitative information. The sizes and nucleic acid contents of Escherichia coli and Pseudomonas aeruginosa were studied during antimicrobial exposure as well as during the PAE period by staining the organisms with propidium iodide and analyzing them with flow cytometry and fluorescence microscopy. The effects of ampicillin, ceftriaxone, ciprofloxacin, gentamicin, and rifampin were studied for E. coli, whereas for P. aeruginosa imipenem and ciprofloxacin were investigated. After exposure of E. coli to ampicillin, ceftriaxone, and ciprofloxacin, filamentous organisms were observed by fluorescence microscopy. These changes in morphology were reflected by increased forward light scatter (FSC) and nucleic acid content as measured by flow cytometry. For the beta-lactams the extent of filamentation increased in a dose-dependent manner after drug removal, resulting in formation of distinct subpopulations of bacteria. These changes peaked at 20 to 35 min, and bacteria returned to normal after 90 min after drug removal. In contrast, the subpopulations induced by ciprofloxacin did not return to normal until > 180 min after the end of the classically defined PAE. Rifampin resulted in formation of small organisms with low FSC, whereas no distinctive characteristics were noted after gentamicin exposure. For P. aeruginosa an identifiable subpopulation of large globoid cells and increased nucleic acid content was detected after exposure to imipenem. These changes persisted past the PAE, as defined by viability counting. Swollen organisms with increased FSC were detected after ciprofloxacin exposure, even persisting during bacterial growth. In summary, for beta-lactam antibiotics and ciprofloxacin, the PAE is characterized by dynamic formation of enlarged cell populations of increased nucleic acid content, whereas rifampin induces a decrease in size and nucleic acid content in the organisms. Flow cytometry is an ideal method for future studies of bacterial phenotypic characteristics during the PAE.
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Affiliation(s)
- M Gottfredsson
- Department of Immunology, Landspítalinn National University Hospital, and University of Iceland Medical School, Reykjavik.
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34
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García-Ochoa F, Santos VE, Alcón A. Intracellular compounds quantification by means of flow cytometry in bacteria: application to xanthan production by Xanthomonas campestris. Biotechnol Bioeng 1998; 57:87-94. [PMID: 10099182 DOI: 10.1002/(sici)1097-0290(19980105)57:1<87::aid-bit11>3.0.co;2-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The use of flow cytometry (FCM) to quantitatively analyze intracellular compounds is studied. FCM is a very useful technique for individual cell studies in microbial systems, and gives access to information which cannot be obtained in any other way. Nevertheless, it provides data in arbitrary units, that is, relative data. This analytical technique could be employed for kinetic modeling of microbial systems and even for internal phenomena analysis, but for this purpose, absolute data-that is concentration of intracellular compounds-must be used. In this work, relative flow cytometry data are transformed into absolute data by means of calibrations employing the same fluorochromes with another technique: spectrofluorymetry. Calibrations of DNA, RNA, and protein intracellular concentrations are presented for the bacteria, Xanthomonas campestris. Other analytical methods, based on biochemical determinations, were also employed to quantify intracellular compounds, but the results obtained are very poor compared with those achieved by means of spectrofluorymetry (SFM). Calibration equations and data obtained by both techniques are given. Evolutions of protein and nucleic acids during Xanthomonas campestris growth and xanthan gum production are shown.
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Affiliation(s)
- F García-Ochoa
- Departamento de Ingeniería Química, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain.
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35
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Abstract
Analytical flow cytometry (AFC) is a novel technique for the rapid (more than 103 s-1) analysis and sorting of single cells based upon simultaneous, multiple measurements of laser-induced particle fluorescence, light scatter and impedance. Originally developed for biomedical use, AFC is now being adapted to analyse single-celled organisms such as phytoplankton and bacteria which are present as trace but functionally important components in seawater. Marine AFC has been used to analytically differentiate and sort these organisms from the heterogeneous assemblage of particles present in seawater. Chlorophyll autofluorescence is an unique biomarker for photosynthetic organisms and has been used to analyse phytoplankton cytometrically both in the laboratory and at sea. A theoretical and practical framework for the cytometric quantitation of cellular chlorophyll in phytoplankton based on autofluorescence is presented. Other subcellular constituents such as enzymes, lipids, nucleic acids and toxins in phytoplankton have recently been analysed by AFC using immuno-, induced or applied fluorescent labelling techniques. Examples are presented together with novel developments in fringe areas of cytometry that are likely to influence AFC of single marine cells in the near future.
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36
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Wallner G, Steinmetz I, Bitter-Suermann D, Amann R. Combination of rRNA-Targeted Hybridization Probes and Immuno-Probes for the Identification of Bacteria by Flow Cytometry. Syst Appl Microbiol 1996. [DOI: 10.1016/s0723-2020(96)80028-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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37
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Porter J, Edwards C, Pickup RW. Rapid assessment of physiological status in Escherichia coli using fluorescent probes. THE JOURNAL OF APPLIED BACTERIOLOGY 1995; 79:399-408. [PMID: 7592133 DOI: 10.1111/j.1365-2672.1995.tb03154.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Rapid and direct viability assessment of Escherichia coli in filtered, sterile lake water was possible using multiparameter flow cytometry. Fluorescent dyes were used as probes for different cellular functions (membrane potential, membrane integrity and intracellular enzyme activity), which were correlated with the ability of the cells to respond to nutrient addition while in a stressed state. Measurement of several criteria circumvented limitations imposed by other methods, and provided extensive evidence for the validity of the methods for monitoring cell viability during adoption of a viable-but-non-culturable state in starved E. coli. Macromolecular staining was concomitantly used to monitor changes in cellular protein, RNA and DNA as additional indicators of physiological status during starvation/stress.
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Affiliation(s)
- J Porter
- Department of Genetics and Microbiology, University of Liverpool, UK
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38
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Ryan C, Nguyen BT, Sullivan SJ. Rapid assay for mycobacterial growth and antibiotic susceptibility using gel microdrop encapsulation. J Clin Microbiol 1995; 33:1720-6. [PMID: 7665635 PMCID: PMC228256 DOI: 10.1128/jcm.33.7.1720-1726.1995] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Effective control of tuberculosis transmission in vulnerable population groups is dependent on rapid identification of the infectious agent and its drug susceptibility. However, the slow growth rate of mycobacteria has undermined the ability to quickly identify antimicrobial resistance. These studies describe a mycobacterial growth assay based on microencapsulation technology used in conjunction with flow cytometric analysis. Mycobacteria were encapsulated in agarose gel microdrops approximately 25 microns in diameter, and colony growth was monitored by using flow cytometry to evaluate the intensity of auramine staining after culture for various times at 37 degrees C. By this method, colony growth of Mycobacterium bovis and M. smegmatis could be quantified within 1 to 3 days after encapsulation. Inhibition of growth by rifampin and isoniazid was also evaluated in this time period, and the presence of an isoniazid-resistant subpopulation representing 3% of the total microorganisms could be detected. This use of encapsulation and flow cytometry has the potential to facilitate rapid and automated evaluation of inhibition of growth by antimicrobial agents and shorten the time frame for analysis of clinical specimens.
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Affiliation(s)
- C Ryan
- One Cell Systems, Inc., Cambridge, Massachusetts 02139, USA
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39
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Jernaes MW, Steen HB. Staining of Escherichia coli for flow cytometry: influx and efflux of ethidium bromide. CYTOMETRY 1994; 17:302-9. [PMID: 7875037 DOI: 10.1002/cyto.990170405] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In an attempt to develop procedures for nucleic acid staining of bacteria for clinical routine assays, the uptake of ethidium bromide (EB) in wild-type Escherichia coli was studied using flow cytometry. Phosphate-buffered saline (PBS) containing EDTA or Tris significantly increased the net uptake of EB compared to PBS only. However, in the majority of the cells, the net uptake reached a constant level that was only a few percent of that of fully permeabilized cells, apparently due to the activity of a metabolically driven efflux pump. When cells were exposed to cold shock (0 degrees C for 30 min) in the presence of Tris or EDTA, the net uptake of dye was similar to that of fully permeabilized cells, whereas it was about half that value in PBS. When cold shock was given in growth medium, the cells split up into four subpopulations, with a net dye uptake ranging from that of fully permeabilized cells to less than 1% of that value. As expected, metabolic inhibitors (Na-azide, 2-deoxy-D-glucose, and CCCP) reduced efflux activity. However, fluorescence of metabolically inhibited cells never exceeded more than about half the value of that of dead cells, possibly reflecting conformational changes in DNA structure as a result of cell death.
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Affiliation(s)
- M W Jernaes
- Department of Biophysics, Norwegian Radium Hospital, Oslo
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40
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Pinder AC, McClelland RG. Rapid assay for pathogenic Salmonella organisms by immunofluorescence flow cytometry. J Microsc 1994; 176:17-22. [PMID: 7799425 DOI: 10.1111/j.1365-2818.1994.tb03495.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Multi-parameter flow cytometry was investigated for the rapid detection of specific serotypes of salmonellas (S. typhimurium and S. montevideo) labelled with fluorescent monoclonal antibodies, both in pure culture and in a typical food matrix (full-fat milk). In all cases, the method was accurate to levels of below 10(4) target cells per ml for a total assay time of about 30 min. After 6 h non-selective enrichment in the presence of a 10,000-fold excess of competing micro-organisms (Escherichia coli) the corresponding detection limit was about 20 cells ml-1. These results suggest that flow cytometry has significant potential for the detection of pathogenic micro-organisms in the food industry.
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Affiliation(s)
- A C Pinder
- Department of Food Biophysics, Norwich Laboratory, U.K
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41
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McClelland RG, Pinder AC. Detection of low levels of specific Salmonella species by fluorescent antibodies and flow cytometry. THE JOURNAL OF APPLIED BACTERIOLOGY 1994; 77:440-7. [PMID: 7989272 DOI: 10.1111/j.1365-2672.1994.tb03447.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The use of fluorescently-labelled monoclonal antibodies, with detection by multi-parameter flow cytometry, was investigated for the rapid detection of salmonellas in pure cultures. Accurate detection of specific Salmonella serotypes was demonstrated down to levels of below 10(4) cells ml-1 (within 30 min) and 1 cell ml-1 (after 6 h non-selective pre-enrichment). This level of sensitivity was attained even in the presence of high levels of other bacterial species that would otherwise have interfered with the results. With combinations of different antibodies, each with a unique fluorescent label, simultaneous analysis for two species was possible.
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Affiliation(s)
- R G McClelland
- Department of Food Biophysics, AFRC Institute of Food Research, Norwich Laboratory, UK
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van der Waaij LA, Mesander G, Limburg PC, van der Waaij D. Direct flow cytometry of anaerobic bacteria in human feces. CYTOMETRY 1994; 16:270-9. [PMID: 7924697 DOI: 10.1002/cyto.990160312] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We describe a flow cytometry method for analysis of noncultured anaerobic bacteria present in human fecal suspensions. Nonbacterial fecal compounds, bacterial fragments, and large aggregates could be discriminated from bacteria by staining with propidium iodide (PI) and setting a discriminator on PI fluorescence and by exclusion of events with large forward scatter. Since anaerobic bacteria, which account for over 99.9% of all fecal bacteria, die during sample preparation, a fixation step was not necessary. A second aim of this study was to investigate the technical possibility of measurement of in vivo IgA coating of fecal anaerobic bacteria as well as their bacterial size. Fecal samples of 22 healthy human volunteers were analyzed. The fluorescence distribution of IgA-coated bacteria labeled with fluorescein isothiocyanate (FITC)-anti-Hu-IgA had overlap with noncoated bacteria. However, with match region subtraction, detection of low levels of specific FITC fluorescence on IgA-coated bacteria was achieved. The median bacterial two-dimensional surface area was 1.0 microns2. To validate flow cytometry data, all samples were analyzed with an image analysis system as well. With this new method, a rapid evaluation of fecal flora with high sensitivity for specific FITC fluorescence is possible without culturing.
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Affiliation(s)
- L A van der Waaij
- Department of Medical Microbiology, University of Groningen, The Netherlands
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43
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Vinogradov AE. Measurement by flow cytometry of genomic AT/GC ratio and genome size. CYTOMETRY 1994; 16:34-40. [PMID: 7518377 DOI: 10.1002/cyto.990160106] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Flow cytometry with the AT-specific fluorochrome Hoechst 33258 (HO) and the GC-specific fluorochrome olivomycin (OM) was used for measurement of base pair specific DNA content in 20 species of vertebrates. The results were found to be in good correlation with the biochemical literature on base pair frequencies (r = 0.972, P < 1 x 10(-8). This correlation allows one to determine the percent of GC/AT-pairs and genome size from flow cytometric data. The genome sizes obtained were compared with the literature data on flow cytometric genome size values determined with the use of propidium iodide (PI) that is usually believed to be non-base pair specific. The results were found to be in general agreement; however, the previously reported slight GC-preference of PI is confirmed. The optimal conditions for flow cytometry of AT/GC ratio and genome size with the use of OM and HO are discussed. The approach can be useful for research in ecology, fisheries science, species conservation, and other environmental studies as a tool for rapid survey of a vast array of specimens.
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Affiliation(s)
- A E Vinogradov
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg
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44
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Green L, Petersen B, Steimel L, Haeber P, Current W. Rapid determination of antifungal activity by flow cytometry. J Clin Microbiol 1994; 32:1088-91. [PMID: 8027319 PMCID: PMC267192 DOI: 10.1128/jcm.32.4.1088-1091.1994] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have developed a rapid assay of antifungal activity which utilizes flow cytometry to detect accumulation of a vital dye in drug-damaged fungal cells. Results of these studies suggest that flow cytometry may provide an improved, rapid method for determining and comparing the antifungal activities of compounds with differing modes of action.
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Affiliation(s)
- L Green
- Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, Indiana 46202
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45
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Kamiya I, Okuda K, Hara K. Flow-cytometric identification and detection of Porphyromonas gingivalis by a LPS specific monoclonal antibody. J Periodontol 1994; 65:309-15. [PMID: 8195974 DOI: 10.1902/jop.1994.65.4.309] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The purpose of this study was to identify Porphyromonas gingivalis (P. gingivalis) by flow cytometry (FCM) using a monoclonal antibody (MAb) OMR-Bg1E directed to P. gingivalis-specific lipopolysaccharide (LPS). The P. gingivalis strains ATCC 33277, 381, ESO75, W50, and A7A1 were selected for the study. Fusobacterium nucleatum (F. nucleatum), Prevotella intermedia (P. intermedia), Campylobacter rectus (C. rectus), Streptococcus sanguis (S. sanguis) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) served as controls. A suspension of 10(7) bacteria/ml of each bacteria was prepared and then reacted with a P. gingivalis specific MAb OMR-Bg1E and fluorescein isothiocyanate (FITC) labeled second antibody. These samples were analyzed by FCM. Bacterial specific binding aggregate on data was separated out by the forward- and side-angle-scatter characteristics, while non-specific binding (NSB) was eliminated by excluding the region with mouse IgG-positive and second antibody-positive area. FCM detected a mean range of 56.2% to 97.2% P. gingivalis strains. There was a 5.1% non-specific binding using FCM to non-P. gingivalis strains. When the P. gingivalis concentration was adjusted to 10(2), 10(4), and 10(6) bacteria/ml, a detection rate of 35.7%, 48.1%, and 91.4%, was respectively observed. The lower sensitivity of the flow cytometric assay was 10(2) bacteria/ml. When P. gingivalis was added to P. intermedia suspension at 1, 20, 40, 60, and 80%, the MAb-positive fraction yielded by FCM displayed a coefficient of determination of 0.967 with the actual percentage of P. gingivalis and could be regressed to a linear function.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- I Kamiya
- Department of Periodontology, Niigata University School of Dentistry, Japan
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46
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Raybourne RB, Bunning VK. Bacterium-host cell interactions at the cellular level: fluorescent labeling of bacteria and analysis of short-term bacterium-phagocyte interaction by flow cytometry. Infect Immun 1994; 62:665-72. [PMID: 8300223 PMCID: PMC186155 DOI: 10.1128/iai.62.2.665-672.1994] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Flow cytometry is a potentially powerful tool for analyzing the interactions of facultative intracellular bacteria and macrophages on a cellular level, particularly when fluorochromes are used to label the bacteria. We labeled Listeria monocytogenes and Salmonella typhimurium with a lipophilic dye, PKH-2, and used flow cytometry to investigate phagocytosis by J774A.1 cells and short-term bacterial survival. Labeled and unlabeled bacteria were identical in terms of viability, growth kinetics, and survival within macrophages, although recovery per macrophage was much greater for L. monocytogenes than for S. typhimurium. Using L. monocytogenes as a prototypical facultative intracellular bacterium, we estimated bacterial survival during phagocytosis on the basis of linear fluorescence measurements of infected J774A.1 cells and recovery of L. monocytogenes from sorted cells. The lower percentage of surviving L. monocytogenes in macrophages containing higher bacterial loads indicated the accumulation of nonviable bacteria within phagocytes. Removal of the external source of viable bacteria by washes and gentamicin treatment reduced the percentage of surviving intracellular L. monocytogenes to a baseline level, and all baseline levels were similar, regardless of bacterial load. Listeria enrichment recoveries, derived from individually sorted J774A.1 cells, demonstrated the heterogeneity of macrophages in intracellular bacterial survival, especially within heavily infected cells. These results indicated that survival of L. monocytogenes was dependent on the adaptations of a small fraction of bacteria within a population of macrophages which permit intracellular growth.
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Affiliation(s)
- R B Raybourne
- Division of Virulence Assessment, Food and Drug Administration, Laurel, Maryland 20708
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47
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Affiliation(s)
- H A Crissman
- Division of Biomedical Sciences, Los Alamos National Laboratory, New Mexico 87545
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48
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Sharma RV, Edwards RT, Beckett R. Physical Characterization and Quantification of Bacteria by Sedimentation Field-Flow Fractionation. Appl Environ Microbiol 1993; 59:1864-75. [PMID: 16348964 PMCID: PMC182173 DOI: 10.1128/aem.59.6.1864-1875.1993] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Studies in microbial ecology require accurate measures of cell number and biomass. Although epifluorescence microscopy is an accepted and dependable method for determining cell numbers, current methods of converting biovolume to biomass are error prone, tedious, and labor-intensive. This paper describes a technique with sedimentation field-flow fractionation to enumerate bacteria and determine their density, size, and mass. Using cultured cells of different shapes and sizes, we determined optimum values for separation run parameters and sample-handling procedures. The technique described can separate and detect 4′, 6-diamidino-2-phenylindole-stained cells and generate a fractogram from which cell numbers and their size or mass distribution can be calculated. A direct method for estimating bacterial biomass (dry organic matter content) which offers distinct advantages over present methods for calculating biomass has been developed.
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Affiliation(s)
- R V Sharma
- Water Studies Centre, Department of Chemistry, Monash University, 900 Dandenong Road, Caulfield East, Victoria, Australia 3145
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49
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Christensen H, Bakken LR, Olsen RA. Soil bacterial DNA and biovolume profiles measured by flow-cytometry. FEMS Microbiol Lett 1993. [DOI: 10.1111/j.1574-6968.1993.tb05804.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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50
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Wallner G, Amann R, Beisker W. Optimizing fluorescent in situ hybridization with rRNA-targeted oligonucleotide probes for flow cytometric identification of microorganisms. CYTOMETRY 1993; 14:136-43. [PMID: 7679962 DOI: 10.1002/cyto.990140205] [Citation(s) in RCA: 806] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A combination of fluorescent rRNA-targeted oligonucleotide probes ("phylogenetic stains") and flow cytometry was used for a high resolution automated analysis of mixed microbial populations. Fixed cells of bacteria and yeasts were hybridized in suspension with fluorescein- or tetramethylrhodamine-labeled oligonucleotide probes complementary to group-specific regions of the 16S ribosomal RNA (rRNA) molecules. Quantifying probe-conferred cell fluorescence by flow cytometry, we could discriminate between target and nontarget cell populations. We critically examined changes of the hybridization conditions, kinetics of the hybridization, and posthybridization treatments. Intermediate probe concentrations, addition of detergent to the hybridization buffer, and a posthybridization washing step were found to increase the signal to noise ratio. We could demonstrate a linear correlation between growth rate and probe-conferred fluorescence of Escherichia coli and Pseudomonas cepacia cells. Oligonucleotides labeled with multiple fluorochromes showed elevated levels of nonspecific binding and therefore could not be used to lower the detection limits, which still restrict studies with fluorescing rRNA-targeted oligonucleotide probes to well-growing microbial cells. Two probes of different specificities--one labeled with fluorescein, the other with tetramethylrhodamine--could be applied simultaneously for dual color analysis.
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Affiliation(s)
- G Wallner
- Lehrstuhl für Mikrobiologie, Technische Universität München, Germany
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