51
|
Strik DPBTB, Picot M, Buisman CJN, Barrière F. pH and Temperature Determine Performance of Oxygen Reducing Biocathodes. ELECTROANAL 2012. [DOI: 10.1002/elan.201200358] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
52
|
Istanbullu O, Babauta J, Nguyen HD, Beyenal H. Electrochemical biofilm control: mechanism of action. BIOFOULING 2012; 28:769-78. [PMID: 22827804 PMCID: PMC4247835 DOI: 10.1080/08927014.2012.707651] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Although it has been previously demonstrated that an electrical current can be used to control biofilm growth on metal surfaces, the literature results are conflicting and there is no accepted mechanism of action. One of the suggested mechanisms is the production of hydrogen peroxide (H(2)O(2)) on metal surfaces. However, there are literature studies in which H(2)O(2) could not be detected in the bulk solution. This is most likely because H(2)O(2) was produced at a low concentration near the surface and could not be detected in the bulk solution. The goals of this research were (1) to develop a well-controlled system to explain the mechanism of action of the bioelectrochemical effect on 316L stainless steel (SS) surfaces and (2) to test whether the produced H(2)O(2) can reduce cell growth on metal surfaces. It was found that H(2)O(2) was produced near 316L SS surfaces when a negative potential was applied. The H(2)O(2) concentration increased towards the surface, while the dissolved oxygen decreased when the SS surface was polarized to -600 mV(Ag/AgCl). When polarized and non-polarized surfaces with identical Pseudomonas aeruginosa PAO1 biofilms were continuously fed with air-saturated growth medium, the polarized surfaces showed minimal biofilm growth while there was significant biofilm growth on the non-polarized surfaces. Although there was no detectable H(2)O(2) in the bulk solution, it was found that the surface concentration of H(2)O(2) was able to prevent biofilm growth.
Collapse
|
53
|
Szkotak R, Niepa THR, Jawrani N, Gilbert JL, Jones MB, Ren D. Differential Gene Expression to Investigate the Effects of Low-level Electrochemical Currents on Bacillus subtilis. AMB Express 2011; 1:39. [PMID: 22078549 PMCID: PMC3294250 DOI: 10.1186/2191-0855-1-39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 11/11/2011] [Indexed: 12/22/2022] Open
Abstract
With the emergence and spread of multidrug resistant bacteria, effective methods to eliminate both planktonic bacteria and those embedded in surface-attached biofilms are needed. Electric currents at μA-mA/cm2 range are known to reduce the viability of bacteria. However, the mechanism of such effects is still not well understood. In this study, Bacillus subtilis was used as the model Gram-positive species to systematically investigate the effects of electrochemical currents on bacteria including the morphology, viability, and gene expression of planktonic cells, and viability of biofilm cells. The data suggest that weak electrochemical currents can effectively eliminate B. subtilis both as planktonic cells and in biofilms. DNA microarray results indicate that the genes associated with oxidative stress response, nutrient starvation, and membrane functions were induced by electrochemical currents. These findings suggest that ions and oxidative species generated by electrochemical reactions might be important for the killing effects of these currents.
Collapse
Affiliation(s)
- Robert Szkotak
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA
- Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Tagbo H R Niepa
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA
- Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Nikhil Jawrani
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA
- Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Jeremy L Gilbert
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA
- Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
| | | | - Dacheng Ren
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA
- Syracuse Biomaterials Institute, Syracuse University, Syracuse, NY 13244, USA
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
- Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY 13244, USA
| |
Collapse
|
54
|
Ben-Yoav H, Amzel T, Sternheim M, Belkin S, Rubin A, Shacham-Diamand Y, Freeman A. Signal amelioration of electrophoretically deposited whole-cell biosensors using external electric fields. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
55
|
Ben-Yoav H, Freeman A, Sternheim M, Shacham-Diamand Y. An electrochemical impedance model for integrated bacterial biofilms. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2010.12.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
56
|
Benedetti A, Bramanti L, Tsounis G, Faimali M, Pavanello G, Rossi S, Gili JM, Santangelo G. Applying cathodically polarised substrata to the restoration of a high value coral. BIOFOULING 2011; 27:799-809. [PMID: 21797738 DOI: 10.1080/08927014.2011.604870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Larval settlement of the high value red coral, Corallium rubrum, was studied on three different CaCO(3) substrata, viz. lithogenic (marble), electro-accreted calcium carbonate in the presence and in the absence of cathodic polarisation. The last two substrata consisted of stainless steel plates galvanically coupled with Zn anodes. The electrochemical characterization of the settlement device was studied in order to investigate correlations between cathodic parameters (polarisation potential, current density, calcareous deposit composition) and larval settlement. The results obtained in the natural habitat (at 35 m depth) showed that settlement was five times lower on the electro-accreted aragonite in the presence of low cathodic current densities (i≤1 μA cm(-2)) compared to both marble tiles and electro-accreted aragonite in the absence of polarisation. These last two substrata showed similar settlement values. The implications of these findings on restoration strategies for C. rubrum are discussed.
Collapse
|
57
|
Kerr A, Hodgkiess T, Cowling M, Beveridge C, Smith M, Parr A. A novel technique to prevent bacterial fouling, using imposed surface potential. J Appl Microbiol 2010. [DOI: 10.1111/j.1365-2672.1998.tb05272.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
58
|
Woznica A, Karcz J, Nowak A, Gmur A, Bernas T. Spatial Architecture of Nitrifying Bacteria Biofilm Immobilized on Polyurethane Foam in an Automatic Biodetector for Water Toxicity. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2010; 16:1-11. [PMID: 20810011 DOI: 10.1017/s1431927610093815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We describe the architecture of nitrifying bacteria biofilms immobilized on a three-dimensional (3D) polyurethane foam that permits efficient water flow through a bioreactor. The 3D spatial organization of immobilized bacterial colonies is characterized on three resolution levels with X-ray tomography, light confocal microscopy, and scanning electron microscopy (SEM). Using these techniques we demonstrate biofilm distribution in the foam and the existence of several modes of binding of bacteria to the foam. Computed X-ray tomography permits observation of the distribution of the biofilm in the whole open cellular polyurethane material volume and estimation of biofilm volume. SEM and confocal laser scanning microscopy techniques permit 3D visualization of biofilm structure. Three distinct immobilization patterns could be observed in the open cellular polyurethane material: (1) large irregular aggregates of bacterial biofilm that exist as irregular biofilm fragments, rope-like structures, or biofilm layers on the foam surface; (2) spherical (pom-pom) aggregates of bacteria localized on the external surface of biofilm; and (3) biofilm threads adherent to the surface of polyurethane foam. Finally, we demonstrate that immobilized bacteria exhibit metabolic activity and growth.
Collapse
Affiliation(s)
- Andrzej Woznica
- Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia, 40-032 Katowice, Poland
| | | | | | | | | |
Collapse
|
59
|
Microbial growth inhibition by alternating electric fields in mice with Pseudomonas aeruginosa lung infection. Antimicrob Agents Chemother 2010; 54:3212-8. [PMID: 20547811 DOI: 10.1128/aac.01841-09] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
High-frequency, low-intensity electric fields generated by insulated electrodes have previously been shown to inhibit bacterial growth in vitro. In the present study, we tested the effect of these antimicrobial fields (AMFields) on the development of lung infection caused by Pseudomonas aeruginosa in mice. We demonstrate that AMFields (10 MHz) significantly inhibit bacterial growth in vivo, both as a stand-alone treatment and in combination with ceftazidime. In addition, we show that peripheral (skin) heating of about 2 degrees C can contribute to bacterial growth inhibition in the lungs of mice. We suggest that the combination of alternating electric fields, together with the heat produced during their application, may serve as a novel antibacterial treatment modality.
Collapse
|
60
|
Feris K, Otto C, Tinker J, Wingett D, Punnoose A, Thurber A, Kongara M, Sabetian M, Quinn B, Hanna C, Pink D. Electrostatic interactions affect nanoparticle-mediated toxicity to gram-negative bacterium Pseudomonas aeruginosa PAO1. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4429-4436. [PMID: 20000362 DOI: 10.1021/la903491z] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nanoscale materials can have cytotoxic effects. Here we present the first combined empirical and theoretical investigation of the influence of electrostatic attraction on nanoparticle cytotoxicity. Modeling electrostatic interactions between cells and 13 nm spheres of zinc oxide nanoparticles provided insight into empirically determined variations of the minimum inhibitory concentrations between four differently charged isogenic strains of Pseudomonas aeruginosa PAO1. We conclude that controlling the electrostatic attraction between nanoparticles and their cellular targets may permit the modulation of nanoparticle cytotoxicity.
Collapse
Affiliation(s)
- Kevin Feris
- Department of Biology, Boise State University, Boise, Idaho 83725, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
61
|
Hamilton S, Bongaerts RJM, Mulholland F, Cochrane B, Porter J, Lucchini S, Lappin-Scott HM, Hinton JCD. The transcriptional programme of Salmonella enterica serovar Typhimurium reveals a key role for tryptophan metabolism in biofilms. BMC Genomics 2009; 10:599. [PMID: 20003355 PMCID: PMC2805695 DOI: 10.1186/1471-2164-10-599] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Accepted: 12/11/2009] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Biofilm formation enhances the capacity of pathogenic Salmonella bacteria to survive stresses that are commonly encountered within food processing and during host infection. The persistence of Salmonella within the food chain has become a major health concern, as biofilms can serve as a reservoir for the contamination of food products. While the molecular mechanisms required for the survival of bacteria on surfaces are not fully understood, transcriptional studies of other bacteria have demonstrated that biofilm growth triggers the expression of specific sets of genes, compared with planktonic cells. Until now, most gene expression studies of Salmonella have focused on the effect of infection-relevant stressors on virulence or the comparison of mutant and wild-type bacteria. However little is known about the physiological responses taking place inside a Salmonella biofilm. RESULTS We have determined the transcriptomic and proteomic profiles of biofilms of Salmonella enterica serovar Typhimurium. We discovered that 124 detectable proteins were differentially expressed in the biofilm compared with planktonic cells, and that 10% of the S. Typhimurium genome (433 genes) showed a 2-fold or more change in the biofilm compared with planktonic cells. The genes that were significantly up-regulated implicated certain cellular processes in biofilm development including amino acid metabolism, cell motility, global regulation and tolerance to stress. We found that the most highly down-regulated genes in the biofilm were located on Salmonella Pathogenicity Island 2 (SPI2), and that a functional SPI2 secretion system regulator (ssrA) was required for S. Typhimurium biofilm formation. We identified STM0341 as a gene of unknown function that was needed for biofilm growth. Genes involved in tryptophan (trp) biosynthesis and transport were up-regulated in the biofilm. Deletion of trpE led to decreased bacterial attachment and this biofilm defect was restored by exogenous tryptophan or indole. CONCLUSIONS Biofilm growth of S. Typhimurium causes distinct changes in gene and protein expression. Our results show that aromatic amino acids make an important contribution to biofilm formation and reveal a link between SPI2 expression and surface-associated growth in S. Typhimurium.
Collapse
Affiliation(s)
- Shea Hamilton
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
- Department of Biological Sciences, University of Exeter, Exeter, EX4 4PS, UK
- Shea Hamilton, Faculty of Medicine, Imperial College London, Norfolk Place, London, W2 1PG, UK; Brett Cochrane, Unilever SEAC, Colworth Science Park, Sharnbrook, Bedfordshire, MK44 1LQ, UK
| | - Roy JM Bongaerts
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
| | - Francis Mulholland
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
| | - Brett Cochrane
- School of Biological Sciences, University of Southampton, Southampton, SO16 7PX, UK
- Shea Hamilton, Faculty of Medicine, Imperial College London, Norfolk Place, London, W2 1PG, UK; Brett Cochrane, Unilever SEAC, Colworth Science Park, Sharnbrook, Bedfordshire, MK44 1LQ, UK
| | - Jonathan Porter
- National Laboratory Service, Starcross Laboratory, Staplake Mount, Starcross, EX6 8PE, UK
| | - Sacha Lucchini
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
| | | | - Jay CD Hinton
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin 2, Ireland
| |
Collapse
|
62
|
Wong HS, Townsend KM, Fenwick SG, Trengove RD, O'Handley RM. Comparative susceptibility of planktonic and 3-day-old Salmonella Typhimurium biofilms to disinfectants. J Appl Microbiol 2009; 108:2222-8. [PMID: 20002868 DOI: 10.1111/j.1365-2672.2009.04630.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To compare the susceptibility of a 3-day-old biofilm and planktonic Salmonella to disinfectants at different exposure times. We hypothesize that Salmonella biofilms are more resilient to disinfectants compared to planktonic Salmonella. METHODS AND RESULTS The susceptibility of planktonic cells to disinfectants was tested by a modified version of the Council of Europe suspension test EN 1276. Salmonella biofilms were formed using the Calgary Biofilm Device. Results show that 3-day-old Salmonella biofilms are less susceptible to the disinfectants benzalkonium chloride, chlorhexidine gluconate, citric acid, quaternary ammonium compounds, sodium hypochlorite (SH) and ethanol, compared to planktonic Salmonella. Surprisingly, the results also demonstrate that low concentrations of SH were more effective against a 3-day-old biofilm compared to high concentrations of SH. CONCLUSIONS While all the disinfectants evaluated were able to reduce biofilm-associated cells at concentrations and contact times sufficient to eliminate planktonic cells, there were still sufficient viable cells remaining in the biofilm to cause further contamination and potential infection. SIGNIFICANCE AND IMPACT OF THE STUDY Protocols for the use of chemical disinfectants need to include biofilm susceptibility testing. There is a requirement for an effective and standardized tool for determining the susceptibility of biofilms to disinfectants.
Collapse
Affiliation(s)
- H S Wong
- Environmental Biotechnology Cooperative Research Centre, School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA, Australia.
| | | | | | | | | |
Collapse
|
63
|
Chiang WC, Hilbert LR, Schroll C, Tolker-Nielsen T, Møller P. Bacterial inhibiting surfaces caused by the effects of silver release and/or electrical field. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.02.112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
64
|
Abstract
Bacteria growing in biofilms cause a wide range of human infections. Biofilm bacteria are resistant to antimicrobics at levels 500 to 5,000 times higher than those needed to kill non-biofilm bacteria. In vitro experiments have shown that electric current can enhance the activity of some antimicrobial agents against certain bacteria in biofilms; this has been termed the ''bioelectric effect''. Direct electrical current has already been safely used in humans for fracture healing. Application of direct electric current with antimicrobial chemotherapy in humans could theoretically abrogate the need to remove the device in device-related infections, a procedure associated with substantial morbidity and cost. In this article, we review what has been described in the literature with regards to the bioelectric effect.
Collapse
Affiliation(s)
- J L Del Pozo
- Infectious Diseases Research Laboratory, Mayo Clinic Rochester, Minnesota and Division of Infectious Diseases, Department of Medicine, Mayo Clinic Rochester, Minnesota - USA
| | | | | |
Collapse
|
65
|
Biofilm Plaque and Hydrodynamic Effects on Mass Transfer, Fluoride Delivery and Caries. J Am Dent Assoc 2008; 139:1182-90. [PMID: 18762628 DOI: 10.14219/jada.archive.2008.0333] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
66
|
Effect of electrical current on the activities of antimicrobial agents against Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis biofilms. Antimicrob Agents Chemother 2008; 53:35-40. [PMID: 18725436 DOI: 10.1128/aac.00237-08] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial biofilms are resistant to conventional antimicrobial agents. Prior in vitro studies have shown that electrical current (EC) enhances the activities of aminoglycosides, quinolones, and oxytetracycline against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus epidermidis, Escherichia coli, and Streptococcus gordonii. This phenomenon, known as the bioelectric effect, has been only partially defined. The purpose of this work was to study the in vitro bioelectric effect on the activities of 11 antimicrobial agents representing a variety of different classes against P. aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), and S. epidermidis. An eight-channel current generator/controller and eight chambers delivering a continuous flow of fresh medium with or without antimicrobial agents and/or EC to biofilm-coated coupons were used. No significant decreases in the numbers of log(10) CFU/cm(2) were seen after exposure to antimicrobial agents alone, with the exception of a 4.57-log-unit reduction for S. epidermidis and trimethoprim-sulfamethoxazole. We detected a statistically significant bioelectric effect when vancomycin plus 2,000 microamperes EC were used against MRSA biofilms (P = 0.04) and when daptomycin and erythromycin were used in combination with 200 or 2,000 microamperes EC against S. epidermidis biofilms (P = 0.02 and 0.0004, respectively). The results of these experiments indicate that the enhancement of the activity of antimicrobial agents against biofilm organisms by EC is not a generalizable phenomenon across microorganisms and antimicrobial agents.
Collapse
|
67
|
Abstract
Weak electric currents generated using conductive electrodes have been shown to increase the efficacy of antibiotics against bacterial biofilms, a phenomenon termed "the bioelectric effect." The purposes of the present study were (i) to find out whether insulated electrodes that generate electric fields without "ohmic" electric currents, and thus are not associated with the formation of metal ions and free radicals, can inhibit the growth of planktonic bacteria and (ii) to define the parameters that are most effective against bacterial growth. The results obtained indicate that electric fields generated using insulated electrodes can inhibit the growth of planktonic Staphylococcus aureus and Pseudomonas aeruginosa and that the effect is amplitude and frequency dependent, with a maximum at 10 MHz. The combined effect of the electric field and chloramphenicol was found to be additive. Several possible mechanisms underlying the observed effect, as well as its potential clinical uses, are discussed.
Collapse
|
68
|
Valle A, Zanardini E, Abbruscato P, Argenzio P, Lustrato G, Ranalli G, Sorlini C. Effects of low electric current (LEC) treatment on pure bacterial cultures. J Appl Microbiol 2008; 103:1376-85. [PMID: 17953548 DOI: 10.1111/j.1365-2672.2007.03374.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS This research focused on the effects of low electric current (LEC) on the cell viability and metabolic activity of Escherichia coli and Bacillus cereus. METHODS AND RESULTS Different LEC intensities at fixed amperage were applied, employing either graphite or copper electrode pairs, and the effects were determined by conventional cultural methods and bioindicators. On E. coli, the LEC with graphite electrodes at 5 and 10 mA led to no significant variation, but at 20 and 40 mA there was increasing inhibition of both the enzymatic activities and growth, and a reduction in ATP content. On B. cereus, similar experiments at the lower amperages did not have any inhibitor effects, however, the 40 mA current stimulated growth, ATP content and some enzymatic activities. The LEC treatment using copper electrodes caused, already at 5 mA, inhibition of bacterial growth and metabolic and enzymatic activities in both E. coli and B. cereus. CONCLUSIONS On the basis of the obtained results using different amperages and electrodes, we can conclude that E. coli seem to be more sensitive compared with B. cereus. SIGNIFICANCE AND IMPACT OF THE STUDY The study increases the knowledge on LEC treatment effects on the pure bacterial cultures.
Collapse
Affiliation(s)
- A Valle
- Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche (DISTAM), Sez. Microbiologia Agraria, Alimentare, Ecologica (MAAE), Università di Milano, Milan, Italy.
| | | | | | | | | | | | | |
Collapse
|
69
|
|
70
|
Abstract
Microbes cohabit our planet and are engaged in a struggle for survival though on a microscopic scale. This endeavor allows them to develop and devise means for survival and proliferation. One such strategy is the formation of biofilms leading to establishment of a protected community. Such multi-communities may consist of harmful and pathogenic microbes, and they may cause economic problems and threats to human health. Biofilms are formed when microorganisms are typically attached to support surfaces. Biofilm-associated cells are sessile and differentiated from their suspended counterparts by generation of an extracellular polymeric substance matrix, reduced growth rates, and the up- and downregulation of specific genes. Biofilm formation is a complex process regulated by diverse characteristics of the growth medium, substratum, and cell surface. Development of strategies to control or prevent biofilms requires a thorough understanding of the biofilm development process. Biofilm research has witnessed exponential growth, and exciting findings have been reported. This has led us to visualize some previously un-thought-of and fascinating events. This article aims to provide an overview of biofilm research and associated challenges.
Collapse
Affiliation(s)
- V S Bhinu
- Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki, Japan.
| |
Collapse
|
71
|
Perez-Roa RE, Tompkins DT, Paulose M, Grimes CA, Anderson MA, Noguera DR. Effects of localised, low-voltage pulsed electric fields on the development and inhibition of Pseudomonas aeruginosa biofilms. BIOFOULING 2006; 22:383-90. [PMID: 17178571 DOI: 10.1080/08927010601053541] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
This work describes the use of low-voltage (0.5 - 5 V) pulsed electric fields to prevent Pseudomonas aeruginosa biofilm development. Interdigitated electrodes (IDEs) with 29-mum spacing between 22-mum-wide electrodes, were used as a platform where the effect of localised, high-strength electric fields could be tested. Alternating current, square-wave pulses were applied to the IDEs in 1 sec intervals. A two-level, three-variable factorial design experiment was used to detect the effects of applied voltage, frequency, and pulse duty ratio (i.e. percentage of pulsing time over one cycle) on the inhibition of biofilm formation. The observations indicated that a pulse configuration of 1% duty ratio, 5 V, and 200 Hz frequency reduced the area of the electrodes covered by biofilm by 50%. In general, the application of low-duty ratio pulses had a positive effect on preventing biofouling. Comparatively, frequency and applied voltage were observed to have less influence on biofouling.
Collapse
Affiliation(s)
- Rodolfo E Perez-Roa
- Department of Civil & Environmental Engineering, University of Wisconsin - Madison, Madison, Wisconsin 53706, USA
| | | | | | | | | | | |
Collapse
|
72
|
Shirtliff ME, Bargmeyer A, Camper AK. Assessment of the ability of the bioelectric effect to eliminate mixed-species biofilms. Appl Environ Microbiol 2005; 71:6379-82. [PMID: 16204561 PMCID: PMC1265951 DOI: 10.1128/aem.71.10.6379-6382.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Microbes have been able to persist in water distribution systems through the development of multicellular communities known as biofilms. This study evaluated the usefulness of the bioelectric effect for the elimination of water distribution system biofilms from annular reactors. The bioelectric effect did not have any bactericidal action either alone or when coupled with free chlorine.
Collapse
Affiliation(s)
- Mark E Shirtliff
- Department of Biomedical Sciences, Dental School, University of Maryland-Baltimore, 666 W. Baltimore Street, Baltimore, MD 21201, USA.
| | | | | |
Collapse
|
73
|
Enhancement of Glutaraldehyde Biocidal Efficacy by the Application of an Electric Field. Effect on Sessile Cells and on Cells Released by the Biofilm. World J Microbiol Biotechnol 2005. [DOI: 10.1007/s11274-004-8288-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
74
|
Ng AW, Bidani A, Heming TA. Innate host defense of the lung: effects of lung-lining fluid pH. Lung 2005; 182:297-317. [PMID: 15742242 DOI: 10.1007/s00408-004-2511-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2004] [Indexed: 10/25/2022]
Abstract
Lung-lining fluid (LLF) is a primary constituent of the pulmonary host defense system. It is distributed continuously throughout the respiratory tract but is heterogeneous regarding its chemistry and physiology between the conducting airways and alveoli. The conducting airways are lined with airway surface liquid (ASL), a mucus gel-aqueous sol complex that interacts functionally with epithelial cilia as the mucociliary escalator. The alveoli are lined with alveolar subphase fluid (AVSF) and pulmonary surfactant. AVSF sterility is maintained in part by the phagocytic activity of resident alveolar macrophages. Normal ASL and AVSF are both more acidic than blood plasma. However, the details of acid-base regulation differ between the two media. Appreciable transepithelial acid-base flux is possible across the airway epithelium, whereas the alveolar epithelium is relatively impermeable to transepithelial acid-base flux. Moreover, one must consider the influence of resident macrophages on AVSF pH. Resident macrophages occupy a sizable fraction of AVSF by volume and are a substantial source of metabolic H+. The buffering capacities of ASL and AVSF probably are largely due to secreted peptides (e.g., ASL mucins and AVSF surfactant proteins). Acid-base exchange between the extracellular hydrophase and intracellular buffering systems of resident macrophages represents an additional buffer pool for AVSF. The pH of ASL and AVSF can be depressed by disease or inflammation. Low pH is predicted to suppress microbe clearance from the airways and alveoli, increase pathogen survival in both regions, and alter mediator release by resident macrophages and recruited leukocytes thereby increasing the propensity for bystander cell injury. Overall, ASL/AVSF pH is expected to be a major determinant of lung host defense responses.
Collapse
Affiliation(s)
- Amelia W Ng
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | | | | |
Collapse
|
75
|
Hunter RC, Beveridge TJ. Application of a pH-sensitive fluoroprobe (C-SNARF-4) for pH microenvironment analysis in Pseudomonas aeruginosa biofilms. Appl Environ Microbiol 2005; 71:2501-10. [PMID: 15870340 PMCID: PMC1087576 DOI: 10.1128/aem.71.5.2501-2510.2005] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An important feature of microbial biofilms is the development of four-dimensional physical and chemical gradients in space and time. There is need for novel approaches to probe these so-called microenvironments to determine their effect on biofilm-specific processes. In this study, we describe the use of seminaphthorhodafluor-4F 5-(and-6) carboxylic acid (C-SNARF-4) for pH microenvironment analysis in Pseudomonas aeruginosa biofilms. C-SNARF-4 is a fluorescent ratiometric probe that allows pH quantification independent of probe concentration and/or laser intensity. By confocal scanning laser microscopy, C-SNARF-4 revealed pH heterogeneity throughout the biofilm in both the x,y and x,z planes, with values ranging from pH 5.6 (within the biofilm) to pH 7.0 (bulk fluid). pH values were typically remarkably different than those just a few micrometers away. Although this probe has been successfully used in a number of eukaryotic systems, problems have been reported which describe spectral emission changes as a result of macromolecular interactions with the fluorophore. To assess how the biofilm environment may influence fluorescent properties of the dye, fluorescence of C-SNARF-4 was quantified via spectrofluorometry while the probe was suspended in various concentrations of representative biofilm matrix components (i.e., proteins, polysaccharides, and bacterial cells) and growth medium. Surprisingly, our data demonstrate that few changes in emission spectra occur as a result of matrix interactions below pH 7. These studies suggest that C-SNARF-4 can be used as a reliable indicator of pH microenvironments, which may help elucidate their influence on the medical and geobiological roles of natural biofilms.
Collapse
Affiliation(s)
- Ryan C Hunter
- Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
| | | |
Collapse
|
76
|
Chen MJ, Zhang Z, Bott TR. Effects of operating conditions on the adhesive strength of Pseudomonas fluorescens biofilms in tubes. Colloids Surf B Biointerfaces 2005; 43:61-71. [PMID: 15913966 DOI: 10.1016/j.colsurfb.2005.04.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 04/14/2005] [Indexed: 11/29/2022]
Abstract
Understanding the mechanical properties of biofilms, especially the force required to disrupt them and remove them from substrata is very important to development of antibiofouling strategies. In this work, a novel micromanipulation technique with a specially designed T-shaped probe has been developed to serve as an experimental means to measure directly the adhesive strength of biofouling deposits on the surface of a glass test stud. The basic principle of this novel technique is to pull away a whole biofilm accumulated on the surface of a glass test stud with T-shaped probe, and to measure simultaneously the force imposed on the biofilm. The adhesive strength between the biofilms and the surface to which they are attached, is defined as the work per unit area required to remove the biofilms from the surface. The biofouling experiments were performed on an elaborate design of a simulated heat exchanger system. A monoculture of Pseudomonas fluorescens was chosen as the fouling microorganism for the laboratory studies. Results indicate that the adhesive strength of the biofilm was affected by the conditions of operation, such as biofilm age, nutrient concentration, suspended cell concentration, pH, surface roughness of the substratum and fluid velocity. As noted, the effect of fluid velocity on the biofilm adhesive strength seemed to overwhelm other factors. At the same operating conditions, the biofilm adhesive strength increased as the fluid velocity increased within the range of 0.6-1.6m/s. In addition, the flow-related biofilm structures were observed that biofilms generally grew as a more compact pattern at the higher fluid velocity. Apparently, the fluid velocity can affect the biofilm structure, which in turn determines the biofilm adhesive strength. The knowledge of the biofilm adhesive strength with associated influences of the operating conditions may be used to define better cleaning procedures.
Collapse
Affiliation(s)
- M J Chen
- Department of Occupational Safety and Hygiene, Fooyin University, Ta-Liao Hsiang, Kaohsiung 831, Taiwan.
| | | | | |
Collapse
|
77
|
Caubet R, Pedarros-Caubet F, Chu M, Freye E, de Belém Rodrigues M, Moreau JM, Ellison WJ. A radio frequency electric current enhances antibiotic efficacy against bacterial biofilms. Antimicrob Agents Chemother 2005; 48:4662-4. [PMID: 15561841 PMCID: PMC529182 DOI: 10.1128/aac.48.12.4662-4664.2004] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial biofilms are notably resistant to antibiotic prophylaxis. The concentration of antibiotic necessary to significantly reduce the number of bacteria in the biofilm matrix can be several hundred times the MIC for the same bacteria in a planktonic phase. It has been observed that the addition of a weak continuous direct electric current to the liquid surrounding the biofilm can dramatically increase the efficacy of the antibiotic. This phenomenon, known as the bioelectric effect, has only been partially elucidated, and it is not certain that the electrical parameters are optimal. We confirm here the bioelectric effect for Escherichia coli biofilms treated with gentamicin and with oxytetracycline, and we report a new bioelectric effect with a radio frequency alternating electric current (10 MHz) instead of the usual direct current. None of the proposed explanations (transport of ions within the biofilm, production of additional biocides by electrolysis, etc.) of the direct current bioelectric effect are applicable to the radio frequency bioelectric effect. We suggest that this new phenomenon may be due to a specific action of the radio frequency electromagnetic field upon the polar parts of the molecules forming the biofilm matrix.
Collapse
Affiliation(s)
- R Caubet
- Unité Sécurité Microbiologique des Aliments, Institut des Sciences et Techniques des Aliments de Bordeaux, Université de Bordeaux 1, Talence, France.
| | | | | | | | | | | | | |
Collapse
|
78
|
Ng AW, Bidani A, Heming TA. Innate host defense of the lung: effects of lung-lining fluid pH. Lung 2004; 182:297-317. [PMID: 15742242 DOI: 10.1007/s00408004-2511-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2004] [Indexed: 05/23/2023]
Abstract
Lung-lining fluid (LLF) is a primary constituent of the pulmonary host defense system. It is distributed continuously throughout the respiratory tract but is heterogeneous regarding its chemistry and physiology between the conducting airways and alveoli. The conducting airways are lined with airway surface liquid (ASL), a mucus gel-aqueous sol complex that interacts functionally with epithelial cilia as the mucociliary escalator. The alveoli are lined with alveolar subphase fluid (AVSF) and pulmonary surfactant. AVSF sterility is maintained in part by the phagocytic activity of resident alveolar macrophages. Normal ASL and AVSF are both more acidic than blood plasma. However, the details of acid-base regulation differ between the two media. Appreciable transepithelial acid-base flux is possible across the airway epithelium, whereas the alveolar epithelium is relatively impermeable to transepithelial acid-base flux. Moreover, one must consider the influence of resident macrophages on AVSF pH. Resident macrophages occupy a sizable fraction of AVSF by volume and are a substantial source of metabolic H+. The buffering capacities of ASL and AVSF probably are largely due to secreted peptides (e.g., ASL mucins and AVSF surfactant proteins). Acid-base exchange between the extracellular hydrophase and intracellular buffering systems of resident macrophages represents an additional buffer pool for AVSF. The pH of ASL and AVSF can be depressed by disease or inflammation. Low pH is predicted to suppress microbe clearance from the airways and alveoli, increase pathogen survival in both regions, and alter mediator release by resident macrophages and recruited leukocytes thereby increasing the propensity for bystander cell injury. Overall, ASL/AVSF pH is expected to be a major determinant of lung host defense responses.
Collapse
Affiliation(s)
- Amelia W Ng
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | | | | |
Collapse
|
79
|
Parkar SG, Flint SH, Brooks JD. Physiology of biofilms of thermophilic bacilli-potential consequences for cleaning. J Ind Microbiol Biotechnol 2003; 30:553-60. [PMID: 14513382 DOI: 10.1007/s10295-003-0081-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2002] [Accepted: 07/07/2003] [Indexed: 10/26/2022]
Abstract
Thermophilic Bacillus species readily attached and grew on stainless steel surfaces, forming mature biofilms of >10(6.0) cells/cm2 in 6 h on a surface inoculated with the bacteria. Clean stainless steel exposed only to pasteurized skim milk at 55 degrees C developed a mature biofilm of >10(6.0) cells/cm2 within 18 h. When bacilli were inoculated onto the steel coupons, 18-h biofilms were 30 microm thick. Biofilm growth followed a repeatable pattern, with a reduction in the numbers of bacteria on the surface occurring after 30 h, followed by a recovery. This reduction in numbers was associated with the production of a substance that inhibited the growth of the bacteria. Variations in the environment, including pH and molarity, affected the viability of the cells. Chemicals that attack the polysaccharide matrix of the biofilm were particularly effective in killing and removing cells from the biofilm, demonstrating the importance of polysaccharides in the persistence of these biofilms. Treatment of either the biofilm or a clean stainless steel surface with lysozyme killed biofilm cells and prevented the attachment of any bacteria exposed to the surface. This suggests that lysozyme may have potential as an alternative control method for biofilms of these bacteria.
Collapse
Affiliation(s)
- S G Parkar
- Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | | | | |
Collapse
|
80
|
Ranalli G, Iorizzo M, Lustrato G, Zanardini E, Grazia L. Effects of low electric treatment on yeast microflora. J Appl Microbiol 2003; 93:877-83. [PMID: 12392536 DOI: 10.1046/j.1365-2672.2002.01758.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To contribute to the understanding of phenomena related to different intensity electric current treatments on the growth and metabolism of selected micro-organisms using laboratory samples of pure and co-cultures (Saccharomyces cerevisiae strain 404 and Hanseniaspora guilliermondii strain 465). METHODS AND RESULTS Low electric current (10, 30, 50 and 100 mA) was applied to prepared samples. Parameters, such as polarity, treatment duration (18-48 h) and type of inoculum yeast, were varied one at a time to highlight their cause-effect relationships. The effects on cell activity as well as microflora viability were assessed. Bioindicators capable of describing the phenomena caused by the electric current on the microflora were identified. CONCLUSIONS Results demonstrated that a low voltage treatment using graphite electrodes had a greater effect on the viable S. cerevisiae strain 404 microflora. There was less bactericidal activity in the S. cerevisiae strain 404 than in the H. guilliermondii strain 465. SIGNIFICANCE AND IMPACT OF THE STUDY These results may be of significant importance in the development of new technological processes in the fields of agriculture and food, particularly new fermenting process controls.
Collapse
Affiliation(s)
- G Ranalli
- DISTAAM, Università del Molise, Campobasso, Italy.
| | | | | | | | | |
Collapse
|
81
|
Affiliation(s)
- David Davies
- Department of Biological Sciences, State University of New York, Binghamton, New York 13902, USA.
| |
Collapse
|
82
|
Chandra J, Kuhn DM, Mukherjee PK, Hoyer LL, McCormick T, Ghannoum MA. Biofilm formation by the fungal pathogen Candida albicans: development, architecture, and drug resistance. J Bacteriol 2001; 183:5385-94. [PMID: 11514524 PMCID: PMC95423 DOI: 10.1128/jb.183.18.5385-5394.2001] [Citation(s) in RCA: 1100] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2001] [Accepted: 06/27/2001] [Indexed: 01/15/2023] Open
Abstract
Biofilms are a protected niche for microorganisms, where they are safe from antibiotic treatment and can create a source of persistent infection. Using two clinically relevant Candida albicans biofilm models formed on bioprosthetic materials, we demonstrated that biofilm formation proceeds through three distinct developmental phases. These growth phases transform adherent blastospores to well-defined cellular communities encased in a polysaccharide matrix. Fluorescence and confocal scanning laser microscopy revealed that C. albicans biofilms have a highly heterogeneous architecture composed of cellular and noncellular elements. In both models, antifungal resistance of biofilm-grown cells increased in conjunction with biofilm formation. The expression of agglutinin-like (ALS) genes, which encode a family of proteins implicated in adhesion to host surfaces, was differentially regulated between planktonic and biofilm-grown cells. The ability of C. albicans to form biofilms contrasts sharply with that of Saccharomyces cerevisiae, which adhered to bioprosthetic surfaces but failed to form a mature biofilm. The studies described here form the basis for investigations into the molecular mechanisms of Candida biofilm biology and antifungal resistance and provide the means to design novel therapies for biofilm-based infections.
Collapse
Affiliation(s)
- J Chandra
- Center for Medical Mycology, University Hospitals of Cleveland, and Department of Dermatology, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | | | | | | | | |
Collapse
|
83
|
Chandra J, Kuhn DM, Mukherjee PK, Hoyer LL, McCormick T, Ghannoum MA. Biofilm formation by the fungal pathogen Candida albicans: development, architecture, and drug resistance. J Bacteriol 2001. [PMID: 11514524 DOI: 10.1128/jb.183.18.5385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023] Open
Abstract
Biofilms are a protected niche for microorganisms, where they are safe from antibiotic treatment and can create a source of persistent infection. Using two clinically relevant Candida albicans biofilm models formed on bioprosthetic materials, we demonstrated that biofilm formation proceeds through three distinct developmental phases. These growth phases transform adherent blastospores to well-defined cellular communities encased in a polysaccharide matrix. Fluorescence and confocal scanning laser microscopy revealed that C. albicans biofilms have a highly heterogeneous architecture composed of cellular and noncellular elements. In both models, antifungal resistance of biofilm-grown cells increased in conjunction with biofilm formation. The expression of agglutinin-like (ALS) genes, which encode a family of proteins implicated in adhesion to host surfaces, was differentially regulated between planktonic and biofilm-grown cells. The ability of C. albicans to form biofilms contrasts sharply with that of Saccharomyces cerevisiae, which adhered to bioprosthetic surfaces but failed to form a mature biofilm. The studies described here form the basis for investigations into the molecular mechanisms of Candida biofilm biology and antifungal resistance and provide the means to design novel therapies for biofilm-based infections.
Collapse
Affiliation(s)
- J Chandra
- Center for Medical Mycology, University Hospitals of Cleveland, and Department of Dermatology, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | | | | | | | | |
Collapse
|
84
|
McLeod BR, Fortun S, Costerton JW, Stewart PS. Enhanced bacterial biofilm control using electromagnetic fields in combination with antibiotics. Methods Enzymol 1999; 310:656-70. [PMID: 10547827 DOI: 10.1016/s0076-6879(99)10051-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- B R McLeod
- College of Graduate Studies, Montana State University, Bozeman 59717-2580, USA
| | | | | | | |
Collapse
|
85
|
Stoodley P, Lewandowski Z, Boyle JD, Lappin-Scott HM. Structural deformation of bacterial biofilms caused by short-term fluctuations in fluid shear: An in situ investigation of biofilm rheology. Biotechnol Bioeng 1999. [DOI: 10.1002/(sici)1097-0290(19991005)65:1<83::aid-bit10>3.0.co;2-b] [Citation(s) in RCA: 269] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
86
|
Stewart PS, Wattanakaroon W, Goodrum L, Fortun SM, McLeod BR. Electrolytic generation of oxygen partially explains electrical enhancement of tobramycin efficacy against Pseudomonas aeruginosa biofilm. Antimicrob Agents Chemother 1999; 43:292-6. [PMID: 9925521 PMCID: PMC89066 DOI: 10.1128/aac.43.2.292] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The role of electrolysis products, including protons, hydroxyl ions, reactive oxygen intermediates, oxygen, hydrogen, and heat, in mediating electrical enhancement of killing of Pseudomonas aeruginosa biofilms by tobramycin (the bioelectric effect) was investigated. The log reduction in biofilm viable cell numbers compared to the numbers for the untreated positive control effected by antibiotic increased from 2.88 in the absence of electric current to 5.58 in the presence of electric current. No enhancement of antibiotic efficacy was observed when the buffer composition was changed to simulate the reduced pH that prevails during electrolysis. Neither did stabilization of the pH during electrical treatment by increasing the buffer strength eliminate the bioelectric effect. The temperature increase measured in our experiments, less than 0.2 degree C, was far too small to account for the greatly enhanced antibiotic efficacy. The addition of sodium thiosulfate, an agent capable of rapidly neutralizing reactive oxygen intermediates, did not abolish electrical enhancement of killing. The bioelectric effect persisted when all of the ionic constituents of the medium except the two phosphate buffer components were omitted. This renders the possibility of electrochemical generation of an inhibitory ion, such as nitrite from nitrate, an unlikely explanation for electrical enhancement. The one plausible explanation for the bioelectric effect revealed by this study was the increased delivery of oxygen to the biofilm due to electrolysis. When gaseous oxygen was bubbled into the treatment chamber during exposure to tobramycin (without electric current), a 1.8-log enhancement of killing resulted. The enhancement of antibiotic killing by oxygen was not due simply to physical disturbances caused by sparging the gas because similar delivery of gaseous hydrogen caused no enhancement whatsoever.
Collapse
Affiliation(s)
- P S Stewart
- Center for Biofilm Engineering, Montana State University-Bozeman 59717-3980, USA.
| | | | | | | | | |
Collapse
|
87
|
Souli M, Giamarellou H. Effects of slime produced by clinical isolates of coagulase-negative staphylococci on activities of various antimicrobial agents. Antimicrob Agents Chemother 1998; 42:939-41. [PMID: 9559814 PMCID: PMC105573 DOI: 10.1128/aac.42.4.939] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A novel in vitro semiquantitative method was developed to investigate the influence of staphylococcal slime on the activities of 22 antimicrobial agents. Pefloxacin, teicoplanin, and vancomycin demonstrated remarkable decreases in efficacy: 30, 52, and 63%, respectively. The activity of rifampin was not significantly reduced (0.99%), whereas all other agents tested were modestly affected (<15% decrease). These data could be influential in the treatment of implant-associated infections caused by slime-producing staphylococci.
Collapse
Affiliation(s)
- M Souli
- First Department of Propedeutic Medicine, Laiko General Hospital, Athens University School of Medicine, Greece
| | | |
Collapse
|