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Yeo JH, Low JQ, Begam N, Leow WT, Kwa ALH. Can flow cytometric measurements of reactive oxygen species levels determine minimal inhibitory concentrations and antibiotic susceptibility testing for Acinetobacter baumannii? PLoS One 2024; 19:e0305939. [PMID: 38913680 PMCID: PMC11195951 DOI: 10.1371/journal.pone.0305939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 06/08/2024] [Indexed: 06/26/2024] Open
Abstract
Current antimicrobial susceptibility testing (AST) requires 16-24 hours, delaying initiation of appropriate antibiotics. Hence, there is a need for rapid AST. This study aims to develop and evaluate the feasibility of a rapid flow cytometric AST assay to determine minimum inhibitory concentration (MIC) for carbapenem-resistant Acinetobacter baumannii (CRAB). Antibiotic exposure causes increased intracellular reactive oxygen species (ROS) in bacteria. We hypothesized that ROS can be used as a marker to determine MIC. We assessed three CRAB clinical isolates across fifteen antibiotics at various concentrations in a customized 96-well microtiter plate. The antibiotics assessed include amikacin, beta-lactams (ampicillin/sulbactam, aztreonam, cefepime, ceftolozane/tazobactam, doripenem, imipenem, meropenem, and piperacillin/tazobactam), levofloxacin, polymyxin B, rifampicin, trimethoprim/sulfamethoxazole, and tetracyclines (tigecycline and minocycline). These clinical CRAB isolates were assessed for ROS after antibiotic treatment. Increased ROS levels indicated by increased RedoxSensorTM Green (RSG) fluorescence intensity was assessed using flow cytometry (FCM). MIC was set as the lowest antibiotic concentration that gives a ≥1.5-fold increase in mode RSG fluorescence intensity (MICRSG). Accuracy of MICRSG was determined by comparing against microtiter broth dilution method performed under CLSI guidelines. ROS was deemed accurate in determining the MICs for β-lactams (83.3% accuracy) and trimethoprim/sulfamethoxazole (100% accuracy). In contrast, ROS is less accurate in determining MICs for levofloxacin (33.3% accuracy), rifampicin (0% accuracy), amikacin (33.3% accuracy), and tetracyclines (33.3% accuracy). Collectively, this study described an FCM-AST assay to determine antibiotic susceptibility of CRAB isolates within 5 hours, reducing turnaround time up to 19 hours.
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Affiliation(s)
- Jia Hao Yeo
- Department of Pharmacy, Singapore General Hospital, Singapore, Singapore
- SingHealth-Duke-NUS Academic Clinical Programme, Singapore, Singapore
| | - Jia Qian Low
- Department of Pharmacy, Singapore General Hospital, Singapore, Singapore
| | - Nasren Begam
- Department of Pharmacy, Singapore General Hospital, Singapore, Singapore
| | - Wan-Ting Leow
- Department of Pharmacy, Singapore General Hospital, Singapore, Singapore
| | - Andrea Lay-Hoon Kwa
- Department of Pharmacy, Singapore General Hospital, Singapore, Singapore
- SingHealth-Duke-NUS Academic Clinical Programme, Singapore, Singapore
- Department of Pharmacy, NUS, Singapore, Singapore
- Emerging Infection Diseases Program, Duke-NUS Graduate Medical School, Singapore, Singapore
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Bolat M, Hatipoğlu H, Köroğlu M, Toptan H, Altındiş M. Use of flow cytometry method to detect contaminations of platelet suspensions. World J Microbiol Biotechnol 2024; 40:222. [PMID: 38811387 PMCID: PMC11136822 DOI: 10.1007/s11274-024-04030-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/21/2024] [Indexed: 05/31/2024]
Abstract
In this study, it was aimed to investigate bacterial contamination in apheresis platelet suspensions (APS) by automated blood culture system and flow cytometry method (FCM).33 spiked APS each using 11 bacterial strains (5 standard strains, 6 clinical isolates), were prepared in three different dilutions (1-10, 10-50, 50-100 cfu/mL), incubated in two different temperatures (35-37 °C and 22-24 °C) and different incubation times (18-96 h) evaluated by FCM. This three different dilutions were also inoculated into special platelet culture bottles (BacT/ALERT® BPA) and loaded into the blood culture system. Additionally 80 APSs routinely prepared in the Transfusion Center were evaluated by both FCM and the blood culture system. Platelets were lysed by freeze-thaw method.All spiked samples were positive with BacT/ALERT® BPA in 12-18 h. In 96 h incubation at 22-24 °C, the presence of bacteria was detected by FCM in all other samples (31/33) except low dilutions (1-10 and 10-100 CFU/ml) of K.pneumoniae standard strain. In the 35-37 °C, the presence of bacteria was detected by FCM in all samples (33/33) after 48 h of incubation. In routine APS one sample detected as positive (Bacillus simplex) with BacT/ALERT® BPA and no positivity was detected by FCM.The freeze-thaw method, which we have optimized for the lysis of platelets, is very practical and can be easily applied. The BacT/ALERT® system has been found to be very sensitive in detecting bacterial contamination in PSs. Flow cytometry method has been found to be successful, fast, easy to use and low cost in detecting bacterial contamination in PSs.
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Affiliation(s)
- Mehtap Bolat
- Sakarya University Health Sciences Institute, Sakarya, Turkey
| | - Hüseyin Hatipoğlu
- Medical Microbiology Laboratory, Sakarya Training and Research Hospital, Sakarya, Turkey
| | - Mehmet Köroğlu
- Faculty of Medicine, Department of Medical Microbiology, Sakarya University, Sakarya, Turkey
| | - Hande Toptan
- Medical Microbiology Laboratory, Sakarya Training and Research Hospital, Sakarya, Turkey.
| | - Mustafa Altındiş
- Faculty of Medicine, Department of Medical Microbiology, Sakarya University, Sakarya, Turkey
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3
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Inglis TJJ, Paton TF, Kopczyk MK, Mulroney KT, Carson CF. Same-day antimicrobial susceptibility test using acoustic-enhanced flow cytometry visualized with supervised machine learning. J Med Microbiol 2020; 69:657-669. [PMID: 31665100 PMCID: PMC7451041 DOI: 10.1099/jmm.0.001092] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 09/23/2019] [Indexed: 11/18/2022] Open
Abstract
Purpose. Antimicrobial susceptibility is slow to determine, taking several days to fully impact treatment. This proof-of-concept study assessed the feasibility of using machine-learning techniques for analysis of data produced by the flow cytometer-assisted antimicrobial susceptibility test (FAST) method we developed.Methods. We used machine learning to assess the effect of antimicrobial agents on bacteria, comparing FAST results with broth microdilution (BMD) antimicrobial susceptibility tests (ASTs). We used Escherichia coli (1), Klebsiella pneumoniae (1) and Staphylococcus aureus (2) strains to develop the machine-learning algorithm, an expanded panel including these plus E. coli (2), K. pneumoniae (3), Proteus mirabilis (1), Pseudomonas aeruginosa (1), S. aureus (2) and Enterococcus faecalis (1), tested against FAST and BMD (Sensititre, Oxoid), then two representative isolates directly from blood cultures.Results. Our data machines defined an antibiotic-unexposed population (AUP) of bacteria, classified the FAST result by antimicrobial concentration range, and determined a concentration-dependent antimicrobial effect (CDE) to establish a predicted inhibitory concentration (PIC). Reference strains of E. coli, K. pneumoniae and S. aureus tested with different antimicrobial agents demonstrated concordance between BMD results and machine-learning analysis (CA, categoric agreement of 91 %; EA, essential agreement of 100 %). CA was achieved in 35 (83 %) and EA in 28 (67 %) by machine learning on first pass in a challenge panel of 27 Gram-negative and 15 Gram-positive ASTs. Same-day AST results were obtained from clinical E. coli (1) and S. aureus (1) isolates.Conclusions. The combination of machine learning with the FAST method generated same-day AST results and has the potential to aid early antimicrobial treatment decisions, stewardship and detection of resistance.
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Affiliation(s)
- Timothy J. J. Inglis
- School of Medicine, Faculty of Health and Medical Sciences, the University of Western Australia, Perth, Australia
- The Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, Faculty of Health and Medical Sciences, the University of Western Australia, Perth, Australia
- Department of Microbiology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Nedlands WA, Australia
| | - Teagan F. Paton
- Department of Microbiology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Nedlands WA, Australia
| | - Malgorzata K. Kopczyk
- Department of Microbiology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Nedlands WA, Australia
| | - Kieran T. Mulroney
- School of Medicine, Faculty of Health and Medical Sciences, the University of Western Australia, Perth, Australia
- The Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, Faculty of Health and Medical Sciences, the University of Western Australia, Perth, Australia
- Translational Renal Research Group, Harry Perkins Institute of Medical Research, Nedlands WA 6009, Australia
| | - Christine F. Carson
- The Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, Faculty of Health and Medical Sciences, the University of Western Australia, Perth, Australia
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Georgiou PC, Mouton JW, Pournaras S, Meletiadis J. Bacterial quantification in tissue homogenates from in vivo pharmacodynamic studies using growth curves. J Med Microbiol 2020; 69:676-684. [PMID: 32228800 DOI: 10.1099/jmm.0.001183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Introduction. Quantification of bacterial load in tissue homogenates in in vivo pharmacodynamic studies is cumbersome and time-consuming.Aim. We therefore developed a new method for quantifying bacterial load in tissue homogenates of animals treated with a β-lactam and β-lactamase inhibitor using growth curves.Methods. The log10 colony-forming units (c.f.u.) ml-1 of 184 thigh and lung homogenates from female CD-1 mice infected intranasally and intramuscularly with 4 Pseudomonas aeruginosa, 4 Klebsiella pneumoniae, 3 Enterobacter cloacae and 2 Escherichia coli strains treated with a β-lactam drug and tazobactam were calculated using the standard approach of serial quantitative cultures and analysis of growth curves. Growth curves were obtained with continuous (every 10 min) monitoring of optical density at 630 nm (OD630) after 20 µl tissue homogenates were inoculated in total volume of 200 µl Mueller-Hinton broth in 96-well microtitration plates and incubated at 37 °C for 18 h.Results. The best correlation between log10 c.f.u. ml-1 determined with the serial quantitative cultures and growth curves was found at the time point corresponding to an OD630 of 0.25 increase above the baseline OD (average of first five timepoints) (R 2=0.918-0.999). The median (range) differences between the two methods was -0.19 (-1.79-1.69) with 86-97 % of all isolates and species being within 1 log10 c.f.u. ml-1 with 1 h hands-on-time and <13 h of incubation for 96 samples. Pharmacodynamic analysis showed similar dose-response relationships and 1 log kill dose estimations (paired t-test, P=0.112).Conclusion. The new technique resulted in comparable c.f.u. counts to those for the standard serial dilution/culture technique with minimal hands-on and turnaround times.
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Affiliation(s)
- Panagiota-Christina Georgiou
- Clinical Microbiology Laboratory, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Johan W Mouton
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Spyros Pournaras
- Clinical Microbiology Laboratory, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Joseph Meletiadis
- Clinical Microbiology Laboratory, Attikon University Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece.,Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
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Cai J, Nichols RG, Koo I, Kalikow ZA, Zhang L, Tian Y, Zhang J, Smith PB, Patterson AD. Multiplatform Physiologic and Metabolic Phenotyping Reveals Microbial Toxicity. mSystems 2018; 3:e00123-18. [PMID: 30417115 PMCID: PMC6222046 DOI: 10.1128/msystems.00123-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/11/2018] [Indexed: 02/06/2023] Open
Abstract
The gut microbiota is susceptible to modulation by environmental stimuli and therefore can serve as a biological sensor. Recent evidence suggests that xenobiotics can disrupt the interaction between the microbiota and host. Here, we describe an approach that combines in vitro microbial incubation (isolated cecal contents from mice), flow cytometry, and mass spectrometry- and 1H nuclear magnetic resonance (NMR)-based metabolomics to evaluate xenobiotic-induced microbial toxicity. Tempol, a stabilized free radical scavenger known to remodel the microbial community structure and function in vivo, was studied to assess its direct effect on the gut microbiota. The microbiota was isolated from mouse cecum and was exposed to tempol for 4 h under strict anaerobic conditions. The flow cytometry data suggested that short-term tempol exposure to the microbiota is associated with disrupted membrane physiology as well as compromised metabolic activity. Mass spectrometry and NMR metabolomics revealed that tempol exposure significantly disrupted microbial metabolic activity, specifically indicated by changes in short-chain fatty acids, branched-chain amino acids, amino acids, nucleotides, glucose, and oligosaccharides. In addition, a mouse study with tempol (5 days gavage) showed similar microbial physiologic and metabolic changes, indicating that the in vitro approach reflected in vivo conditions. Our results, through evaluation of microbial viability, physiology, and metabolism and a comparison of in vitro and in vivo exposures with tempol, suggest that physiologic and metabolic phenotyping can provide unique insight into gut microbiota toxicity. IMPORTANCE The gut microbiota is modulated physiologically, compositionally, and metabolically by xenobiotics, potentially causing metabolic consequences to the host. We recently reported that tempol, a stabilized free radical nitroxide, can exert beneficial effects on the host through modulation of the microbiome community structure and function. Here, we investigated a multiplatform phenotyping approach that combines high-throughput global metabolomics with flow cytometry to evaluate the direct effect of tempol on the microbiota. This approach may be useful in deciphering how other xenobiotics directly influence the microbiota.
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Affiliation(s)
- Jingwei Cai
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Robert G. Nichols
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Imhoi Koo
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Zachary A. Kalikow
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Limin Zhang
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Centre for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS), Wuhan, China
| | - Yuan Tian
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Centre for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences (CAS), Wuhan, China
| | - Jingtao Zhang
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Philip B. Smith
- Metabolomics Facility, Huck Institutes of Life Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Andrew D. Patterson
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
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Jun S, Si F, Pugatch R, Scott M. Fundamental principles in bacterial physiology-history, recent progress, and the future with focus on cell size control: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:056601. [PMID: 29313526 PMCID: PMC5897229 DOI: 10.1088/1361-6633/aaa628] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Bacterial physiology is a branch of biology that aims to understand overarching principles of cellular reproduction. Many important issues in bacterial physiology are inherently quantitative, and major contributors to the field have often brought together tools and ways of thinking from multiple disciplines. This article presents a comprehensive overview of major ideas and approaches developed since the early 20th century for anyone who is interested in the fundamental problems in bacterial physiology. This article is divided into two parts. In the first part (sections 1-3), we review the first 'golden era' of bacterial physiology from the 1940s to early 1970s and provide a complete list of major references from that period. In the second part (sections 4-7), we explain how the pioneering work from the first golden era has influenced various rediscoveries of general quantitative principles and significant further development in modern bacterial physiology. Specifically, section 4 presents the history and current progress of the 'adder' principle of cell size homeostasis. Section 5 discusses the implications of coarse-graining the cellular protein composition, and how the coarse-grained proteome 'sectors' re-balance under different growth conditions. Section 6 focuses on physiological invariants, and explains how they are the key to understanding the coordination between growth and the cell cycle underlying cell size control in steady-state growth. Section 7 overviews how the temporal organization of all the internal processes enables balanced growth. In the final section 8, we conclude by discussing the remaining challenges for the future in the field.
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Affiliation(s)
- Suckjoon Jun
- Department of Physics, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, United States of America. Section of Molecular Biology, Division of Biology, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, United States of America
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7
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Carson CF, Inglis TJJ. Air sampling to assess potential generation of aerosolized viable bacteria during flow cytometric analysis of unfixed bacterial suspensions. Gates Open Res 2018; 1:2. [PMID: 29608197 PMCID: PMC5873458 DOI: 10.12688/gatesopenres.12759.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2018] [Indexed: 01/31/2024] Open
Abstract
This study investigated aerosolized viable bacteria in a university research laboratory during operation of an acoustic-assisted flow cytometer for antimicrobial susceptibility testing by sampling room air before, during and after flow cytometer use. The aim was to assess the risk associated with use of an acoustic-assisted flow cytometer analyzing unfixed bacterial suspensions. Air sampling in a nearby clinical laboratory was conducted during the same period to provide context for the existing background of microorganisms that would be detected in the air. The three species of bacteria undergoing analysis by flow cytometer in the research laboratory were Klebsiella pneumoniae, Burkholderia thailandensis and Streptococcus pneumoniae. None of these was detected from multiple 1000 L air samples acquired in the research laboratory environment. The main cultured bacteria in both locations were skin commensal and environmental bacteria, presumed to have been disturbed or dispersed in laboratory air by personnel movements during routine laboratory activities. The concentrations of bacteria detected in research laboratory air samples were reduced after interventional cleaning measures were introduced and were lower than those in the diagnostic clinical microbiology laboratory. We conclude that our flow cytometric analyses of unfixed suspensions of K. pneumoniae, B. thailandensis and S. pneumoniae do not pose a risk to cytometer operators or other personnel in the laboratory but caution against extrapolation of our results to other bacteria and/or different flow cytometric experimental procedures.
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Affiliation(s)
- Christine F Carson
- School of Biomedical Sciences (M504), Faculty of Health and Medical Sciences, University of Western Australia, Crawley, WA, Australia
| | - Timothy JJ Inglis
- School of Biomedical Sciences (M504), Faculty of Health and Medical Sciences, University of Western Australia, Crawley, WA, Australia
- School of Medicine, Faculty of Health and Medical Sciences, University of Western Australia, Crawley, WA, Australia
- Department of Microbiology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Nedlands, WA, Australia
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8
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Carson CF, Inglis TJ. Air sampling to assess potential generation of aerosolized viable bacteria during flow cytometric analysis of unfixed bacterial suspensions. Gates Open Res 2018; 1:2. [PMID: 29608197 PMCID: PMC5873458 DOI: 10.12688/gatesopenres.12759.2] [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] [Accepted: 02/16/2018] [Indexed: 11/20/2022] Open
Abstract
This study investigated aerosolized viable bacteria in a university research laboratory during operation of an acoustic-assisted flow cytometer for antimicrobial susceptibility testing by sampling room air before, during and after flow cytometer use. The aim was to assess the risk associated with use of an acoustic-assisted flow cytometer analyzing unfixed bacterial suspensions. Air sampling in a nearby clinical laboratory was conducted during the same period to provide context for the existing background of microorganisms that would be detected in the air. The three species of bacteria undergoing analysis by flow cytometer in the research laboratory were
Klebsiella pneumoniae, Burkholderia thailandensis and
Streptococcus pneumoniae. None of these was detected from multiple 1000 L air samples acquired in the research laboratory environment. The main cultured bacteria in both locations were skin commensal and environmental bacteria, presumed to have been disturbed or dispersed in laboratory air by personnel movements during routine laboratory activities. The concentrations of bacteria detected in research laboratory air samples were reduced after interventional cleaning measures were introduced and were lower than those in the diagnostic clinical microbiology laboratory. We conclude that our flow cytometric analyses of unfixed suspensions of
K. pneumoniae, B. thailandensis and
S. pneumoniae do not pose a risk to cytometer operators or other personnel in the laboratory but caution against extrapolation of our results to other bacteria and/or different flow cytometric experimental procedures.
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Affiliation(s)
- Christine F Carson
- School of Biomedical Sciences (M504), Faculty of Health and Medical Sciences, University of Western Australia, Crawley, WA, Australia
| | - Timothy Jj Inglis
- School of Biomedical Sciences (M504), Faculty of Health and Medical Sciences, University of Western Australia, Crawley, WA, Australia.,School of Medicine, Faculty of Health and Medical Sciences, University of Western Australia, Crawley, WA, Australia.,Department of Microbiology, PathWest Laboratory Medicine WA, Queen Elizabeth II Medical Centre, Nedlands, WA, Australia
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9
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Antibiograma rápido en Microbiología Clínica. Enferm Infecc Microbiol Clin 2016; 34:61-8. [DOI: 10.1016/j.eimc.2014.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/25/2014] [Accepted: 11/15/2014] [Indexed: 11/22/2022]
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10
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Nguta JM, Appiah-Opong R, Nyarko AK, Yeboah-Manu D, Addo PGA. Current perspectives in drug discovery against tuberculosis from natural products. Int J Mycobacteriol 2015; 4:165-83. [PMID: 27649863 DOI: 10.1016/j.ijmyco.2015.05.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/03/2015] [Accepted: 05/06/2015] [Indexed: 10/23/2022] Open
Abstract
Currently, one third of the world's population is latently infected with Mycobacterium tuberculosis (MTB), while 8.9-9.9 million new and relapse cases of tuberculosis (TB) are reported yearly. The renewed research interests in natural products in the hope of discovering new and novel antitubercular leads have been driven partly by the increased incidence of multidrug-resistant strains of MTB and the adverse effects associated with the first- and second-line antitubercular drugs. Natural products have been, and will continue to be a rich source of new drugs against many diseases. The depth and breadth of therapeutic agents that have their origins in the secondary metabolites produced by living organisms cannot be compared with any other source of therapeutic agents. Discovery of new chemical molecules against active and latent TB from natural products requires an interdisciplinary approach, which is a major challenge facing scientists in this field. In order to overcome this challenge, cutting edge techniques in mycobacteriology and innovative natural product chemistry tools need to be developed and used in tandem. The present review provides a cross-linkage to the most recent literature in both fields and their potential to impact the early phase of drug discovery against TB if seamlessly combined.
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Affiliation(s)
- Joseph Mwanzia Nguta
- Department of Clinical Pathology, Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana; Department of Public Health, Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, Kenya
| | - Regina Appiah-Opong
- Department of Clinical Pathology, Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Alexander K Nyarko
- Department of Clinical Pathology, Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Dorothy Yeboah-Manu
- Department of Bacteriology, Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Phyllis G A Addo
- Department of Animal Experimentation, Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
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11
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Baker CA, Rubinelli PM, Park SH, Ricke SC. Immuno-based detection of Shiga toxin-producing pathogenic Escherichia coli in food – A review on current approaches and potential strategies for optimization. Crit Rev Microbiol 2015; 42:656-75. [DOI: 10.3109/1040841x.2015.1009824] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Christopher A. Baker
- Department of Food Science, Center for Food Safety, University of Arkansas, Fayetteville, AR, USA
| | - Peter M. Rubinelli
- Department of Food Science, Center for Food Safety, University of Arkansas, Fayetteville, AR, USA
| | - Si Hong Park
- Department of Food Science, Center for Food Safety, University of Arkansas, Fayetteville, AR, USA
| | - Steven C. Ricke
- Department of Food Science, Center for Food Safety, University of Arkansas, Fayetteville, AR, USA
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12
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Comparison of the RAPID-B® flow cytometer and the BAX® system for the detection of non-O157 shiga toxin-producing Escherichia coli (STEC) in beef products. Food Control 2015. [DOI: 10.1016/j.foodcont.2014.08.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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13
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Dusny C, Schmid A. Microfluidic single-cell analysis links boundary environments and individual microbial phenotypes. Environ Microbiol 2014; 17:1839-56. [DOI: 10.1111/1462-2920.12667] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 10/02/2014] [Accepted: 10/11/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Christian Dusny
- Department of Solar Materials; Helmholtz Centre for Environmental Research GmbH - UFZ; Permoserstr. 15 Leipzig DE 04318 Germany
- Laboratory of Chemical Biotechnology; Department of Biochemical and Chemical Engineering; TU Dortmund University; Emil-Figge-Str. 66 D-44227 Dortmund Germany
| | - Andreas Schmid
- Department of Solar Materials; Helmholtz Centre for Environmental Research GmbH - UFZ; Permoserstr. 15 Leipzig DE 04318 Germany
- Laboratory of Chemical Biotechnology; Department of Biochemical and Chemical Engineering; TU Dortmund University; Emil-Figge-Str. 66 D-44227 Dortmund Germany
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14
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Buzatu DA, Moskal TJ, Williams AJ, Cooper WM, Mattes WB, Wilkes JG. An integrated flow cytometry-based system for real-time, high sensitivity bacterial detection and identification. PLoS One 2014; 9:e94254. [PMID: 24718659 PMCID: PMC3981798 DOI: 10.1371/journal.pone.0094254] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 03/13/2014] [Indexed: 11/18/2022] Open
Abstract
Foodborne illnesses occur in both industrialized and developing countries, and may be increasing due to rapidly evolving food production practices. Yet some primary tools used to assess food safety are decades, if not centuries, old. To improve the time to result for food safety assessment a sensitive flow cytometer based system to detect microbial contamination was developed. By eliminating background fluorescence and improving signal to noise the assays accurately measure bacterial load or specifically identify pathogens. These assays provide results in minutes or, if sensitivity to one cell in a complex matrix is required, after several hours enrichment. Conventional assessments of food safety require 48 to 56 hours. The assays described within are linear over 5 orders of magnitude with results identical to culture plates, and report live and dead microorganisms. This system offers a powerful approach to real-time assessment of food safety, useful for industry self-monitoring and regulatory inspection.
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Affiliation(s)
- Dan A. Buzatu
- National Center for Toxicological Research, Food and Drug Administration (FDA), Jefferson, Arkansas, United States of America
- * E-mail:
| | - Ted J. Moskal
- Vivione Biosciences, Pine Bluff, Arkansas, United States of America
| | - Anna J. Williams
- National Center for Toxicological Research, Food and Drug Administration (FDA), Jefferson, Arkansas, United States of America
| | - Willie Mae Cooper
- National Center for Toxicological Research, Food and Drug Administration (FDA), Jefferson, Arkansas, United States of America
| | - William B. Mattes
- PharmPoint Consulting, Poolesville, Maryland, United States of America
| | - Jon G. Wilkes
- National Center for Toxicological Research, Food and Drug Administration (FDA), Jefferson, Arkansas, United States of America
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15
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Role of autofluorescence in flow cytometric analysis of Escherichia coli treated with bactericidal antibiotics. J Bacteriol 2013; 195:4067-73. [PMID: 23836867 DOI: 10.1128/jb.00393-13] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Bactericidal antibiotics kill by different mechanisms as a result of a specific interaction with their cellular targets. Over the past few years, alternative explanations for cidality have been proposed based on a postulated common pathway, depending on the intracellular production of reactive oxygen species. Detection of hydroxyl radicals relies on staining with specific fluorescent dyes that can penetrate the cell and are detected using flow cytometry. Flow cytometry has become an important tool in microbiology to study characteristics of individual cells within large heterogeneous cellular populations. We show here that Escherichia coli treated with different bactericidal antibiotics exhibits increased autofluorescence when analyzed by flow cytometry. We present evidence suggesting that this change in autofluorescence is caused by altered cell morphology upon antibiotic treatment. Consistent with this view, mutant cells that fail to elongate upon norfloxacin treatment show no increased auto-fluorescence response. Finally, we present data demonstrating that changes in autofluorescence can impact the results with fluorescent probes when using flow cytometry and confound the findings obtained with specific dyes. In summary, recent findings that correlate the exposure to cidal antibiotics with the production of reactive oxygen species need to be reconsidered in light of such changes in autofluorescence. Conclusive evidence for an increase of hydroxyl radicals after treatment with such drugs is still missing.
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Konokhova AI, Gelash AA, Yurkin MA, Chernyshev AV, Maltsev VP. High-precision characterization of individualE. colicell morphology by scanning flow cytometry. Cytometry A 2013; 83:568-75. [DOI: 10.1002/cyto.a.22294] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 02/25/2013] [Accepted: 03/15/2013] [Indexed: 11/11/2022]
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17
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Broeren MAC, Maas Y, Retera E, Arents NLA. Antimicrobial susceptibility testing in 90 min by bacterial cell count monitoring. Clin Microbiol Infect 2012; 19:286-91. [PMID: 22390723 PMCID: PMC3597975 DOI: 10.1111/j.1469-0691.2012.03800.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The rise in antimicrobial resistance has become a serious global health problem. Restrictive use of antibiotics seems the only option to temper this accession since research in new antibiotics has halted. Antimicrobial stewardship programmes rely on quick access to susceptibility data. This study evaluated the concept of bacterial cell count monitoring as a fast method to determine susceptibility. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains were tested for amoxicillin/piperacillin and gentamicin by three conventional methods (VITEK2®, Etest® and broth-macrodilution). Bacterial cell count monitoring reliably predicted susceptibility after 90 min for Escherichia coli and after 120 min for Pseudomonas aeruginosa and Staphylococcus aureus without any minor, major or very major discrepancies. Time-to-result was reduced by 74%, 83% and 76%, respectively. Bacterial cell count monitoring shows great potential for rapid susceptibility testing.
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Affiliation(s)
- M A C Broeren
- Máxima Medical Centre, Clinical Laboratory for Chemistry and Haematology, The Netherlands
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19
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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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20
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David F, Berger A, Hänsch R, Rohde M, Franco-Lara E. Single cell analysis applied to antibody fragment production with Bacillus megaterium: development of advanced physiology and bioprocess state estimation tools. Microb Cell Fact 2011; 10:23. [PMID: 21496219 PMCID: PMC3101136 DOI: 10.1186/1475-2859-10-23] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 04/15/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Single cell analysis for bioprocess monitoring is an important tool to gain deeper insights into particular cell behavior and population dynamics of production processes and can be very useful for discrimination of the real bottleneck between product biosynthesis and secretion, respectively. RESULTS Here different dyes for viability estimation considering membrane potential (DiOC2(3), DiBAC4(3), DiOC6(3)) and cell integrity (DiBAC4(3)/PI, Syto9/PI) were successfully evaluated for Bacillus megaterium cell characterization. It was possible to establish an appropriate assay to measure the production intensities of single cells revealing certain product secretion dynamics. Methods were tested regarding their sensitivity by evaluating fluorescence surface density and fluorescent specific concentration in relation to the electronic cell volume. The assays established were applied at different stages of a bioprocess where the antibody fragment D1.3 scFv production and secretion by B. megaterium was studied. CONCLUSIONS It was possible to distinguish between live, metabolic active, depolarized, dormant, and dead cells and to discriminate between high and low productive cells. The methods were shown to be suitable tools for process monitoring at single cell level allowing a better process understanding, increasing robustness and forming a firm basis for physiology-based analysis and optimization with the general application for bioprocess development.
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Affiliation(s)
- Florian David
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Germany
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21
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Müller S, Nebe-von-Caron G. Functional single-cell analyses: flow cytometry and cell sorting of microbial populations and communities. FEMS Microbiol Rev 2010; 34:554-87. [DOI: 10.1111/j.1574-6976.2010.00214.x] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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22
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Díaz M, Herrero M, García LA, Quirós C. Application of flow cytometry to industrial microbial bioprocesses. Biochem Eng J 2010. [DOI: 10.1016/j.bej.2009.07.013] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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23
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Falcioni T, Papa S, Campana R, Manti A, Battistelli M, Baffone W. State transitions of Vibrio parahaemolyticus VBNC cells evaluated by flow cytometry. CYTOMETRY PART B-CLINICAL CYTOMETRY 2008; 74:272-81. [PMID: 18500741 DOI: 10.1002/cyto.b.20427] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Vibrio parahaemolyticus, in response to environmental conditions, may be present in a viable but nonculturable state (VBNC), which can still be responsible for cases of infectious diseases in humans. METHODS The characterization of the cellular states of V. parahaemolyticus during entry into, persistence in, and resuscitation from the VBNC state, was assessed through plate culture method and epifluorescence microscope evaluation of actively respiring cells. Flow cytometry (FCM) in combination with SYBR Green I (SG) and propidium iodide allowed us to distinguish between viable, dead, and damaged-cells. Immunofluorescence labeling detected by FCM was used to study changes in antibody affinity. RESULTS Two groups of bacteria, one with High Nucleic Acid (HNA) and one having Low Nucleic Acid (LNA) content, were differentiated using SG and FCM and each was correlated with cell viability. With the aging of the microcosm, the LNA bacteria population increased while the HNA population gradually disappeared. Cytofluorimetric immunofluorescence analyses showed that the bacterial cell levels dropped from 95% at day 0 to 40% at day 26 and by day 29, antibody affinity was virtually lost. FCM analyses of light scatter signals expressed by cell population highlighted morphological changes indicating a reduction in cell size, as also shown by scanning electron microscopy images and variations in cell structure. CONCLUSIONS The methodology used has provided useful data in relation to the state transitions of V. parahaemolyticus regarding cell viability, antigenic surface components, and the quantification of morphological variations during its entry into the VBNC state.
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Affiliation(s)
- Tania Falcioni
- Centro di Citometria e Citomorfologia, Università Carlo Bo, Urbino, Italy
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BHUNIA ARUNK, BANADA PADMAPRIYA, BANERJEE PRATIK, VALADEZ ANGELA, HIRLEMAN EDANIEL. LIGHT SCATTERING, FIBER OPTIC- AND CELL-BASED SENSORS FOR SENSITIVE DETECTION OF FOODBORNE PATHOGENS. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1745-4581.2007.00077.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Joung YH, Kim HR, Lee MK, Park AJ. Fluconazole susceptibility testing of Candida species by flow cytometry. J Infect 2006; 54:504-8. [PMID: 17084902 DOI: 10.1016/j.jinf.2006.09.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 09/05/2006] [Accepted: 09/15/2006] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Currently, antifungal drug susceptibility testing is labor-intensive, limited by delays in obtaining results and high costs. The purpose of this study was to determine the usefulness of flow cytometry (FCM) antifungal drug susceptibility testing as a routine laboratory procedure. METHODS A total of 24 clinical isolates of Candida spp. and reference strains were tested for susceptibility to fluconazole by FCM using propidium iodide (PI) as an indicator of viability. The minimum inhibitory concentration (MIC) was defined as the lowest concentration of fluconazole that resulted in an increase of 30% in mean channel fluorescence (MCF), compared to the growth control. FCM results were compared with MIC results as determined by the Clinical and Laboratory Standards Institute (CLSI) method. RESULTS An 8h incubation was sufficient for determination of the MICs. The results by FCM at 8h and the NCCLS methods at 24h showed 87.5% agreement to within two drug dilutions. However, the FCM method is labor-intensive in proportion to the larger number of samples. For Candida lusitaniae, MICs by the FCM method showed poor correlation with the CLSI method. CONCLUSIONS Further evaluation is necessary to assess the usefulness of FCM as a technique for routine antifungal MIC testing in the clinical laboratory.
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Affiliation(s)
- Young Hee Joung
- Department of Laboratory Medicine, Chung-Ang University College of Medicine, 65-207, 3-Ka Hangang-Ro, Yongsan-Ku, Seoul 140-757, South Korea
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26
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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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27
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Shapiro HM. The evolution of cytometers. CYTOMETRY. PART A : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR ANALYTICAL CYTOLOGY 2004; 58:13-20. [PMID: 14994215 DOI: 10.1002/cyto.a.10111] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Howard M Shapiro
- The Center for Microbial Cytometry, West Newton, Massachusetts 02465-2513, USA.
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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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Katsuragi T, Tani Y. Single-Cell Sorting of Microorganisms by Flow or Slide-Based (Including Laser Scanning) Cytometry. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/1521-3846(200105)21:2<99::aid-abio99>3.0.co;2-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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30
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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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31
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Affiliation(s)
- M R Melamed
- New York Medical College, Valhalla 10595, USA
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32
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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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Vives-Rego J, Lebaron P, Nebe-von Caron G. Current and future applications of flow cytometry in aquatic microbiology. FEMS Microbiol Rev 2000; 24:429-48. [PMID: 10978545 DOI: 10.1111/j.1574-6976.2000.tb00549.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Flow cytometry has become a valuable tool in aquatic and environmental microbiology that combines direct and rapid assays to determine numbers, cell size distribution and additional biochemical and physiological characteristics of individual cells, revealing the heterogeneity present in a population or community. Flow cytometry exhibits three unique technical properties of high potential to study the microbiology of aquatic systems: (i) its tremendous velocity to obtain and process data; (ii) the sorting capacity of some cytometers, which allows the transfer of specific populations or even single cells to a determined location, thus allowing further physical, chemical, biological or molecular analysis; and (iii) high-speed multiparametric data acquisition and multivariate data analysis. Flow cytometry is now commonly used in aquatic microbiology, although the application of cell sorting to microbial ecology and quantification of heterotrophic nanoflagellates and viruses is still under development. The recent development of laser scanning cytometry also provides a new way to further analyse sorted cells or cells recovered on filter membranes or slides. The main infrastructure limitations of flow cytometry are: cost, need for skilled and well-trained operators, and adequate refrigeration systems for high-powered lasers and cell sorters. The selection and obtaining of the optimal fluorochromes, control microorganisms and validations for a specific application may sometimes be difficult to accomplish.
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Affiliation(s)
- J Vives-Rego
- Departament de Microbiologia, Universitat de Barcelona, Barcelona, Spain.
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Nebe-von-Caron G, Stephens PJ, Hewitt CJ, Powell JR, Badley RA. Analysis of bacterial function by multi-colour fluorescence flow cytometry and single cell sorting. J Microbiol Methods 2000; 42:97-114. [PMID: 11000436 DOI: 10.1016/s0167-7012(00)00181-0] [Citation(s) in RCA: 296] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
With the increased awareness of the problems associated with the growth dependent analysis of bacterial populations, direct optical detection methods such as flow cytometry have enjoyed increased popularity over the last few years. Among the analyses discussed here are: (1) Bacterial discrimination from other particles on the basis of nucleic acid staining, using sample disaggregation to provide fast reliable enumeration while minimizing data artefacts due to post sampling growth; (2) Determination of basic cell functions such as reproductive ability, metabolic activity and membrane integrity, to characterise the physiological state or degree of viability of bacteria; and (3) The use of single cell sorting onto agar plates, microscope slides or into multi-well plates to correlate viability as determined by cell growth with fluorescent labelling techniques. Simultaneous staining with different fluorochromes provides an extremely powerful way to demonstrate culture heterogeneity, and also to understand the functional differences revealed by each stain in practical applications. Analysis of bacterial fermentations showed a considerable drop (20%) in membrane potential and integrity during the latter stages of small scale (5L), well mixed fed-batch fermentations. These changes, not found in either batch or continuous culture fermentations, are probably due to the severe, steadily increasing stress associated with glucose limitation during the fed-batch process, suggesting 'on-line' flow cytometry could improve process control. Heat injured cells can already show up to 4 log of differences in recovery in different pre-enrichment media, thus contributing to the problem of viable but non-culturable cells (VBNC's). Cytometric cell sorting demonstrated decreasing recovery with increasing loss of membrane function. However, a new medium protecting the cells from intracellular and extracellular causes of oxidative stress improved recovery considerably. Actively respiring cells showed much higher recovery improvement than the other populations, demonstrating for the first time the contribution of oxidative respiration to intracellular causes of damage as a key part of the VBNC problem. Finally, absolute and relative frequencies of one species in a complex population were determined using immunofluorescent labelling in combination with the analysis of cell function. The detail and precision of multiparameter flow cytometric measurements of cell function at the single cell level now raise questions regarding the validity of classical, growth dependent viability assessment methods.
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Affiliation(s)
- G Nebe-von-Caron
- Unilever Research Colworth, Bedfordshire, MK44 1LQ, Sharnbrook, UK.
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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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Abstract
Classical microbiology techniques are relatively slow in comparison to other analytical techniques, in many cases due to the need to culture the microorganisms. Furthermore, classical approaches are difficult with unculturable microorganisms. More recently, the emergence of molecular biology techniques, particularly those on antibodies and nucleic acid probes combined with amplification techniques, has provided speediness and specificity to microbiological diagnosis. Flow cytometry (FCM) allows single- or multiple-microbe detection in clinical samples in an easy, reliable, and fast way. Microbes can be identified on the basis of their peculiar cytometric parameters or by means of certain fluorochromes that can be used either independently or bound to specific antibodies or oligonucleotides. FCM has permitted the development of quantitative procedures to assess antimicrobial susceptibility and drug cytotoxicity in a rapid, accurate, and highly reproducible way. Furthermore, this technique allows the monitoring of in vitro antimicrobial activity and of antimicrobial treatments ex vivo. The most outstanding contribution of FCM is the possibility of detecting the presence of heterogeneous populations with different responses to antimicrobial treatments. Despite these advantages, the application of FCM in clinical microbiology is not yet widespread, probably due to the lack of access to flow cytometers or the lack of knowledge about the potential of this technique. One of the goals of this review is to attempt to mitigate this latter circumstance. We are convinced that in the near future, the availability of commercial kits should increase the use of this technique in the clinical microbiology laboratory.
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Alvarez-Barrientos A, Arroyo J, Cantón R, Nombela C, Sánchez-Pérez M. Applications of flow cytometry to clinical microbiology. Clin Microbiol Rev 2000; 13:167-95. [PMID: 10755996 PMCID: PMC100149 DOI: 10.1128/cmr.13.2.167] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Classical microbiology techniques are relatively slow in comparison to other analytical techniques, in many cases due to the need to culture the microorganisms. Furthermore, classical approaches are difficult with unculturable microorganisms. More recently, the emergence of molecular biology techniques, particularly those on antibodies and nucleic acid probes combined with amplification techniques, has provided speediness and specificity to microbiological diagnosis. Flow cytometry (FCM) allows single- or multiple-microbe detection in clinical samples in an easy, reliable, and fast way. Microbes can be identified on the basis of their peculiar cytometric parameters or by means of certain fluorochromes that can be used either independently or bound to specific antibodies or oligonucleotides. FCM has permitted the development of quantitative procedures to assess antimicrobial susceptibility and drug cytotoxicity in a rapid, accurate, and highly reproducible way. Furthermore, this technique allows the monitoring of in vitro antimicrobial activity and of antimicrobial treatments ex vivo. The most outstanding contribution of FCM is the possibility of detecting the presence of heterogeneous populations with different responses to antimicrobial treatments. Despite these advantages, the application of FCM in clinical microbiology is not yet widespread, probably due to the lack of access to flow cytometers or the lack of knowledge about the potential of this technique. One of the goals of this review is to attempt to mitigate this latter circumstance. We are convinced that in the near future, the availability of commercial kits should increase the use of this technique in the clinical microbiology laboratory.
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Affiliation(s)
- A Alvarez-Barrientos
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Spain
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38
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Abstract
BACKGROUND Conventional techniques used to assess bactericidal activities of antibodies are time-consuming; flow cytometry has been used as a rapid alternative. In this study, the membrane potential-sensitive fluorescent probes bis-(1,3-dibutylbarbituric acid) trimethine oxonol (DiBAC4(3)) and Sytox Green, the redox dye cyano-2,3-ditolyl tetrazolium chloride (CTC), and the Baclite viability test kit were used to assess the effects of ceftazidime, ampicillin, and vancomycin on clinical isolates of Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, respectively. METHODS Bacterial cultures were grown to early exponential phase, at which point the antibiotics were added at their breakpoint values, and incubation was allowed to continue. At timed intervals, samples were stained and flow cytometric analysis was performed on a Skatron Argus 100 arc-lamp based dual-parameter flow cytometer. RESULTS All the dyes successfully identified antibiotic-induced damage in the three strains, although different fluorescence responses between the dyes were observed. DiBAC4(3) and Sytox Green overestimated numbers of nonviable bacteria relative to loss of viability as judged by plate counts. CTC, a measure of respiratory activity, revealed antibiotic-induced population heterogeneity illus trated by the development of several subpopulations. The "live" component of the viability kit identified two populations corresponding to viable and nonviable organisms, whereas the "dead" component only revealed single populations, the fluorescence intensity of which increased with antibiotic exposure. CONCLUSIONS Flow cytometry provides a rapid and sensitive technique for the evaluation of the antibacterial activities of antibiotics. The use of a range of fluorophores specific for different cellular characteristics may be beneficial, bearing in mind the different fluorescence responses observed among the dyes used here.
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Affiliation(s)
- M T Suller
- School of Pure and Applied Biology, University of Wales at Cardiff, United Kingdom.
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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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40
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Jepras RI, Paul FE, Pearson SC, Wilkinson MJ. Rapid assessment of antibiotic effects on Escherichia coli by bis-(1,3-dibutylbarbituric acid) trimethine oxonol and flow cytometry. Antimicrob Agents Chemother 1997; 41:2001-5. [PMID: 9303401 PMCID: PMC164052 DOI: 10.1128/aac.41.9.2001] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The effects of selected antibiotics on Escherichia coli were studied by flow cytometry with the fluorescent anionic membrane potential probe bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)]. The actions of azithromycin, cefuroxime, and ciprofloxacin at five times the MIC on E. coli were compared by the traditional CFU assay and flow cytometry. Changes in viable counts of bacteria determined with DiBAC4(3) and by flow cytometry following treatment with the antibiotics showed trends similar to those found by the CFU assays. However, viable counts determined by flow cytometry following antibiotic treatment were 1 to 2 logs higher than those determined by the corresponding CFU assays. All the results obtained by flow cytometry were provided within 10 min after sampling, whereas the conventional CFU assay results took at least 18 h. The results indicated that flow cytometry is a sensitive analytical technique that can rapidly monitor the physiological changes of individual microorganisms following antibiotic action and can provide information on the mode of action of a drug. The membrane potential probe DiBAC4(3) provides a robust flow cytometric indicator for bacterial cell viability.
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Affiliation(s)
- R I Jepras
- SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Harlow, Essex, United Kingdom
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41
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Abstract
A rapid flow cytometric assay for in vitro antifungal drug susceptibility testing was developed by adapting the proposed reference method for broth macrodilution testing of yeasts. Membrane permeability changes caused by the antifungal agent were measured by flow cytometry using propidium iodide, a nucleic acid-binding fluorochrome largely excluded by the intact cell membrane. We determined the in vitro susceptibility of 31 Candida albicans isolates and two quality control strains (Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258) to amphotericin B and fluconazole. Amphotericin B MICs ranged from 0.03 to 2.0 microg/ml, while fluconazole MICs ranged from 0.125 to 128 microg/ml. This method results in clear-cut endpoints that were reproducible. Four-hour incubation was required for fluconazole, whereas a 2-h incubation was sufficient for amphotericin B to provide MICs comparable to the reference macrodilution method developed by the National Committee for Clinical Laboratory Standards Subcommittee on Antifungal Susceptibility Tests. Results of these studies show that flow cytometry provides a rapid and sensitive in vitro method for antifungal susceptibility testing of C. albicans.
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Affiliation(s)
- R Ramani
- Mycology Laboratory, Wadsworth Center, New York State Department of Health, Albany 12201-2002, USA.
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42
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Langsrud S, Sundheim G. Flow cytometry for rapid assessment of viability after exposure to a quaternary ammonium compound. J Appl Microbiol 1996. [DOI: 10.1111/j.1365-2672.1996.tb01934.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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43
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Langsrud S, Sundheim G. Flow cytometry for rapid assessment of viability after exposure to a quaternary ammonium compound. THE JOURNAL OF APPLIED BACTERIOLOGY 1996; 81:411-8. [PMID: 8896352 DOI: 10.1111/j.1365-2672.1996.tb03527.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The use of flow cytometry to rapidly assess the viability of Pseudomonas spp. and Staphylococcus spp. after exposure to a quaternary ammonium compound (QAC) was investigated using rhodamine 123 (Rh 123), Stain A (LIVE Stain) accumulating in viable but not in dead cells (Live/Dead Baclight bacterial viability kit, Molecular Probes Inc., Eugene, OR, USA), and Sytox green (Molecular Probes) accumulating in dead but not viable cells. Staining conditions were optimized for each stain. The fraction of viable cells after exposure to benzalkonium chloride was determined by using the three staining techniques and colony counts on agar medium. For all Staphylococcus spp. tested there was a high correlation the methods based on flow cytometry and colony counts irrespective of which stain was used. Although viable, all Pseudomonas spp. tested accumulated Rh 123 poorly and about 30% failed to accumulate LIVE stain as well. However, the correlation between colony counts and Sytox green labelling of Pseudomonas spp. was high. Our results indicate that flow cytometry together with live or dead cell labelling can be used to study the bactericidal effect of QACs. The methods based on LIVE stain and Sytox green were simpler and less time consuming than Rh 123 labelling. Only Sytox green could be used with all strains of Staphylococcus and Pseudomonas tested.
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Affiliation(s)
- S Langsrud
- MATFORSK, Norwegian Food Research Institute, As, Norway
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44
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Deka C, Steinkamp JA. Time-resolved fluorescence-decay measurement and analysis on single cells by flow cytometry. APPLIED OPTICS 1996; 35:4481-4489. [PMID: 21102863 DOI: 10.1364/ao.35.004481] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A novel method is described for the measurement and analysis of fluorescence decays of individual cells and particles in flow. It combines the rapid measurement capabilities of a flow cytometer and the robust measurement and analysis procedures of time-domain fluorescence-lifetime spectroscopy. For excitation we use a cw laser that is pulse modulated by an electro-optic modulator. The characteristics and the repetition rate of the excitation pulses can be easily adjusted to accommodate fluorescence decays with a wide range of lifetimes.
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45
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Durodie J, Coleman K, Simpson IN, Loughborough SH, Winstanley DW. Rapid detection of antimicrobial activity using flow cytometry. CYTOMETRY 1995; 21:374-7. [PMID: 8608735 DOI: 10.1002/cyto.990210409] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Different antibiotic classes vary considerably in their modes of action and hence in their effects on the bacterial cell. Flow cytometry was used to analyse E. coli cells treated with five antibiotics differing in their modes of action. The ratio of protein content, as measured by fluorescence, to forward light scatter (i.e., FL1:FSC) provided a simple and reliable way of detecting within 2 h of treatment antimicrobial activity at a 0.5 minimum inhibitory concentration. This ability to detect antimicrobial activity rapidly offers considerable advantages in drug research for the rapid detection of novel antimicrobials and may, with further development, find a use in the clinic for rapid susceptibility testing as an aid to the selection of therapy.
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Affiliation(s)
- J Durodie
- SmithKline Beecham Pharmaceuticals, Brockham Park, Betchworth, Surrey, United Kingdom
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46
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Lehman JM, Dickerson E, Friedrich T, Laffin J. Increase in total protein following infection of CV-1 cells with SV40 virus as assayed by flow cytometry. In Vitro Cell Dev Biol Anim 1995; 31:806-10. [PMID: 8564071 DOI: 10.1007/bf02634124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The changes in cell size and total protein were determined for G1-arrested, contact-inhibited CV-1 cells infected with Simian virus 40 (SV40). The assays used were the Biorad total protein assays (Bradford and DC protein assays) on a standard number of cells, total protein as assayed by fluorescein isothiocyanate (FITC) and SR101 by flow cytometry, orthoganol (90 degrees) light scatter by flow cytometry, and direct microscopic measurement with an ocular micrometer. Uninfected CV-1 cells and two cell lines with variations in DNA content (diploid vs. tetraploid) were used as controls for the studies presented. The results demonstrated a 40-60% increase in total protein at 32 to 42 h postinfection. These increases were similar to values obtained due to cellular changes resulting from viral replication and cell death.
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Affiliation(s)
- J M Lehman
- Department of Microbiology, Immunology & Molecular Genetics, Albany Medical College, New York 12208, USA
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47
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Chung JD, Conner S, Stephanopoulos G. Flow cytometric study of differentiating cultures of Bacillus subtilis. CYTOMETRY 1995; 20:324-33. [PMID: 7587720 DOI: 10.1002/cyto.990200408] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report on 1) the development of a flow cytometry-based technique for detecting beta-galactosidase in differentiating cultures of Bacillus subtilis and 2) the application of this technique in the study of early developmental gene expression. The problems associated with generating detectable signals (despite the small size of B. subtilis cells) have been overcome using the fluorogenic substrate 5-octanolyaminofluorescein di-beta-D-galactopyranoside (C8-FDG). Additionally, to control for background fluorescence during the staining process, we included a control population in the C8-FDG staining mixture that consists of cells devoid of the lacZ gene prestained with another dye, PKH26. The distinct emission spectra of C8-fluorescein and PKH26 allow nonspecific C8-FDG staining in this control population to be monitored using two-color analysis. This technique has been applied in the study of developmental gene expression in sporulating cultures of B. subtilis, and it has been found that such cultures are heterogeneous, comprising two cell populations. One population is induced for expression of early sporulation genes, which is determined using lacZ fusions, whereas the other remains uninduced. These results have allowed us to understand better the patterns of gene expression exhibited by wild-type and mutant cultures early during the development process of spore formation.
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Affiliation(s)
- J D Chung
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, USA
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48
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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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49
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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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50
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Abstract
Much could be gained if the scope of flow cytometry could be broadened to the study of entire cell colonies, rather than to populations of single, separate cells. This can be achieved by encapsulating single microbial cells in small spheres in a way that allows each cell to multiply and form a colony within its respective microbead, which is then amenable to analysis by flow cytometry. Methods for performing the encapsulation within beads of appropriate size and homogeneity have been developed (Nir et al., Appl. Environ. Microbiol. 56:2870-2875, 1990). We describe here how a variety of properties of the entrapped colonies, such as mass, growth rate, enzymatic activity, and expression of specific antigens, can be measured, and we discuss how these constructs can be utilized to select microbial mutants.
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Affiliation(s)
- E Sahar
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
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