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Sharma S, Mohler J, Mahajan SD, Schwartz SA, Bruggemann L, Aalinkeel R. Microbial Biofilm: A Review on Formation, Infection, Antibiotic Resistance, Control Measures, and Innovative Treatment. Microorganisms 2023; 11:1614. [PMID: 37375116 DOI: 10.3390/microorganisms11061614] [Citation(s) in RCA: 83] [Impact Index Per Article: 83.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/15/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Biofilm is complex and consists of bacterial colonies that reside in an exopolysaccharide matrix that attaches to foreign surfaces in a living organism. Biofilm frequently leads to nosocomial, chronic infections in clinical settings. Since the bacteria in the biofilm have developed antibiotic resistance, using antibiotics alone to treat infections brought on by biofilm is ineffective. This review provides a succinct summary of the theories behind the composition of, formation of, and drug-resistant infections attributed to biofilm and cutting-edge curative approaches to counteract and treat biofilm. The high frequency of medical device-induced infections due to biofilm warrants the application of innovative technologies to manage the complexities presented by biofilm.
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Affiliation(s)
- Satish Sharma
- Department of Urology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14260, USA
| | - James Mohler
- Department of Urology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Supriya D Mahajan
- Department of Medicine, Division of Allergy, Immunology, and Rheumatology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Stanley A Schwartz
- Department of Urology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14260, USA
- Department of Medicine, Division of Allergy, Immunology, and Rheumatology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
- Department of Medicine, VA Western New York Healthcare System, Buffalo, NY 14215, USA
| | - Liana Bruggemann
- Department of Biomedical Informatics, University at Buffalo, Buffalo, NY 14260, USA
| | - Ravikumar Aalinkeel
- Department of Urology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14260, USA
- Department of Medicine, Division of Allergy, Immunology, and Rheumatology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
- Department of Medicine, VA Western New York Healthcare System, Buffalo, NY 14215, USA
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Chekabab SM, Harel J, Dozois CM. Interplay between genetic regulation of phosphate homeostasis and bacterial virulence. Virulence 2014; 5:786-93. [PMID: 25483775 DOI: 10.4161/viru.29307] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Bacterial pathogens, including those of humans, animals, and plants, encounter phosphate (Pi)-limiting or Pi-rich environments in the host, depending on the site of infection. The environmental Pi-concentration results in modulation of expression of the Pho regulon that allows bacteria to regulate phosphate assimilation pathways accordingly. In many cases, modulation of Pho regulon expression also results in concomitant changes in virulence phenotypes. Under Pi-limiting conditions, bacteria use the transcriptional-response regulator PhoB to translate the Pi starvation signal sensed by the bacterium into gene activation or repression. This regulator is employed not only for the maintenance of bacterial Pi homeostasis but also to differentially regulate virulence. The Pho regulon is therefore not only a regulatory circuit of phosphate homeostasis but also plays an important adaptive role in stress response and bacterial virulence. Here we focus on recent findings regarding the mechanisms of gene regulation that underlie the virulence responses to Pi stress in Vibrio cholerae, Pseudomonas spp., and pathogenic E. coli.
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Affiliation(s)
- Samuel Mohammed Chekabab
- a Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA); Université de Montréal; Faculté de Médecine Vétérinaire ; Saint-Hyacinthe , QC Canada
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Levering V, Wang Q, Shivapooja P, Zhao X, López GP. Soft robotic concepts in catheter design: an on-demand fouling-release urinary catheter. Adv Healthc Mater 2014; 3:1588-96. [PMID: 24668920 DOI: 10.1002/adhm.201400035] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/24/2014] [Indexed: 01/12/2023]
Abstract
Infectious biofilms are problematic in many healthcare-related devices and are especially challenging and ubiquitous in urinary catheters. This report presents an on-demand fouling-release methodology to mechanically disrupt and remove biofilms, and proposes this method for the active removal of infectious biofilms from the previously inaccessible main drainage lumen of urinary catheters. Mature Proteus mirabilis crystalline biofilms detach from silicone elastomer substrates upon application of strain to the substrate, and increasing the strain rate increases biofilm detachment. The study presents a quantitative relationship between applied strain rate and biofilm debonding through an analysis of biofilm segment length and the driving force for debonding. Based on this mechanism, hydraulic and pneumatic elastomer actuation is used to achieve surface strain selectively within the lumen of prototypes of sections of a fouling-release urinary catheter. Proof-of-concept prototypes of sections of active, fouling-release catheters are constructed using techniques typical to soft robotics including 3D printing and replica molding, and those prototypes demonstrate release of mature P. mirabilis crystalline biofilms (e.g., ≈90%) from strained surfaces. These results provide a basis for the development of a new urinary catheter technology in which infectious biofilms are effectively managed through new methods that are entirely complementary to existing approaches.
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Affiliation(s)
- Vrad Levering
- Research Triangle MRSEC; Duke University; Durham NC 27708 USA
- Department of Biomedical Engineering; Duke University; Durham NC 27708 USA
| | - Qiming Wang
- Research Triangle MRSEC; Duke University; Durham NC 27708 USA
- Department of Mechanical Engineering and Materials Science; Duke University; Durham NC 27708 USA
| | | | - Xuanhe Zhao
- Department of Biomedical Engineering; Duke University; Durham NC 27708 USA
- Department of Mechanical Engineering and Materials Science; Duke University; Durham NC 27708 USA
| | - Gabriel P. López
- Research Triangle MRSEC; Duke University; Durham NC 27708 USA
- Department of Biomedical Engineering; Duke University; Durham NC 27708 USA
- Department of Mechanical Engineering and Materials Science; Duke University; Durham NC 27708 USA
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Nucleic acid aptamers: research tools in disease diagnostics and therapeutics. BIOMED RESEARCH INTERNATIONAL 2014; 2014:540451. [PMID: 25050359 PMCID: PMC4090538 DOI: 10.1155/2014/540451] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 03/18/2014] [Indexed: 12/20/2022]
Abstract
Aptamers are short sequences of nucleic acid (DNA or RNA) or peptide molecules which adopt a conformation and bind cognate ligands with high affinity and specificity in a manner akin to antibody-antigen interactions. It has been globally acknowledged that aptamers promise a plethora of diagnostic and therapeutic applications. Although use of nucleic acid aptamers as targeted therapeutics or mediators of targeted drug delivery is a relatively new avenue of research, one aptamer-based drug “Macugen” is FDA approved and a series of aptamer-based drugs are in clinical pipelines. The present review discusses the aspects of design, unique properties, applications, and development of different aptamers to aid in cancer diagnosis, prevention, and/or treatment under defined conditions.
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Savory N, Lednor D, Tsukakoshi K, Abe K, Yoshida W, Ferri S, Jones BV, Ikebukuro K. In silico maturation of binding-specificity of DNA aptamers against Proteus mirabilis. Biotechnol Bioeng 2013; 110:2573-80. [PMID: 23568752 DOI: 10.1002/bit.24922] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 02/27/2013] [Accepted: 03/29/2013] [Indexed: 01/23/2023]
Abstract
Proteus mirabilis is a prominent cause of catheter-associated urinary tract infections (CAUTIs) among patients undergoing long-term bladder catheterization. There are currently no effective means of preventing P. mirabilis infections, and strategies for prophylaxis and rapid early diagnosis are urgently required. Aptamers offer significant potential for development of countermeasures against P. mirabilis CAUTI and are an ideal class of molecules for the development of diagnostics and therapeutics. Here we demonstrate the application of Cell-SELEX to identify DNA aptamers that show high affinity for P. mirabilis. While the aptamers identified displayed high affinity for P. mirabilis cells in dot blotting assays, they also bound to other uropathogenic bacteria. To improve aptamer specificity for P. mirabilis, an in silico maturation (ISM) approach was employed. Two cycles of ISM allowed the identification of an aptamer showing 36% higher specificity, evaluated as a ratio of binding signal for P. mirabilis to that for Escherichia coli (also a cause of CAUTI and the most common urinary tract pathogen). Aptamers that specifically recognize P. mirabilis would have diagnostic and therapeutic values and constitute useful tools for studying membrane-associated proteins in this organism.
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Affiliation(s)
- Nasa Savory
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
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Study of Antibacterial Efficacy of Hybrid Chitosan-Silver Nanoparticles for Prevention of Specific Biofilm and Water Purification. ACTA ACUST UNITED AC 2011. [DOI: 10.1155/2011/693759] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Antibacterial efficacy of silver nanoparticles (Ag NPs) deposited alternatively layer by layer (LBL) on chitosan polymer in the form of a thin film over a quartz plate and stainless steel strip has been studied. An eight-bilayer chitosan/silver (Cs/Ag)8 hybrid was prepared having a known concentration of silver. Techniques such as UV-visible spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES), and atomic force microscopy (AFM) were carried out to understand and elucidate the physical nature of the film. Gram-negative bacteria, Escherichia coli (E. coli), were used as a test sample in saline solution for antibacterial studies. The growth inhibition at different intervals of contact time and, more importantly, the antibacterial properties of the hybrid film on repeated cycling in saline solution have been demonstrated. AFM studies are carried out for the first time on the microbe to know the morphological changes affected by the hybrid film. The hybrid films on aging (3 months) are found to be as bioactive as before. Cytotoxicity experiments indicated good biocompatibility. The hybrid can be a promising bioactive material for the prevention of biofilms specific to E. coli and in purification of water for safe drinking.
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Falagas ME, Kapaskelis AM, Kouranos VD, Kakisi OK, Athanassa Z, Karageorgopoulos DE. Outcome of Antimicrobial Therapy in Documented Biofilm-Associated Infections. Drugs 2009; 69:1351-61. [DOI: 10.2165/00003495-200969100-00005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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O'May GA, Jacobsen SM, Longwell M, Stoodley P, Mobley HLT, Shirtliff ME. The high-affinity phosphate transporter Pst in Proteus mirabilis HI4320 and its importance in biofilm formation. MICROBIOLOGY-SGM 2009; 155:1523-1535. [PMID: 19372157 DOI: 10.1099/mic.0.026500-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Proteus mirabilis causes urinary tract infections (UTIs) in individuals requiring long-term indwelling catheterization. The pathogenesis of this uropathogen is mediated by a number of virulence factors and the formation of crystalline biofilms. In addition, micro-organisms have evolved complex systems for the acquisition of nutrients, including the phosphate-specific transport system, which has been shown to be important in biofilm formation and pathogenesis. A functional Pst system is important during UTIs caused by P. mirabilis HI4320, since transposon mutants in the PstS periplasmic binding protein and the PstA permease protein were attenuated in the CBA mouse model of UTI. These mutants displayed a defect in biofilm formation when grown in human urine. This study focuses on a comparison of the proteomes during biofilm and planktonic growth in phosphate-rich medium and human urine, and microscopic investigations of biofilms formed by the pst mutants. Our data suggest that (i) the Deltapst mutants, and particularly the DeltapstS mutant, are defective in biofilm formation, and (ii) the proteomes of these mutants differ significantly from that of the wild-type. Therefore, since the Pst system of P. mirabilis HI4320 negatively regulates biofilm formation, this system is important for the pathogenesis of these organisms during complicated UTIs.
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Affiliation(s)
- G A O'May
- Department of Microbial Pathogenesis, University of Maryland - Baltimore, Dental School, 650 W. Baltimore Street, Baltimore, MD 21201, USA
| | - S M Jacobsen
- Department of Microbial Pathogenesis, University of Maryland - Baltimore, Dental School, 650 W. Baltimore Street, Baltimore, MD 21201, USA
| | - M Longwell
- Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, Pittsburgh, PA 15212, USA
| | - P Stoodley
- Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, Pittsburgh, PA 15212, USA
| | - H L T Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - M E Shirtliff
- Department of Microbial Pathogenesis, University of Maryland - Baltimore, Dental School, 650 W. Baltimore Street, Baltimore, MD 21201, USA
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Complicated catheter-associated urinary tract infections due to Escherichia coli and Proteus mirabilis. Clin Microbiol Rev 2008; 21:26-59. [PMID: 18202436 DOI: 10.1128/cmr.00019-07] [Citation(s) in RCA: 477] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Catheter-associated urinary tract infections (CAUTIs) represent the most common type of nosocomial infection and are a major health concern due to the complications and frequent recurrence. These infections are often caused by Escherichia coli and Proteus mirabilis. Gram-negative bacterial species that cause CAUTIs express a number of virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, and nutrient acquisition as well as factors that cause damage to the host. These infections can be reduced by limiting catheter usage and ensuring that health care professionals correctly use closed-system Foley catheters. A number of novel approaches such as condom and suprapubic catheters, intermittent catheterization, new surfaces, catheters with antimicrobial agents, and probiotics have thus far met with limited success. While the diagnosis of symptomatic versus asymptomatic CAUTIs may be a contentious issue, it is generally agreed that once a catheterized patient is believed to have a symptomatic urinary tract infection, the catheter is removed if possible due to the high rate of relapse. Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.
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Jacobsen SM, Lane MC, Harro JM, Shirtliff ME, Mobley HLT. The high-affinity phosphate transporter Pst is a virulence factor for Proteus mirabilis during complicated urinary tract infection. ACTA ACUST UNITED AC 2008; 52:180-93. [PMID: 18194341 DOI: 10.1111/j.1574-695x.2007.00358.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Proteus mirabilis is a ubiquitous bacterium associated with complicated urinary tract infection (UTI). Mutagenesis studies of the wild-type strain HI4320 in the CBA mouse model of ascending UTIs have identified attenuated mutants with transposon insertions in genes encoding the high-affinity phosphate transporter Pst (pstS, pstA). The transcription of the pst operon (pstSCAB-phoU) and other members of the phosphate regulon of Escherichia coli, including alkaline phosphatase (AP), are regulated by the two-component regulatory system PhoBR and are repressed until times of phosphate starvation. This normal suppression was relieved in pstS::Tn5 and pstA::Tn5 mutants, which constitutively produced AP regardless of growth conditions. No significant growth defects were observed in vitro for the pst mutants during the independent culture or coculture studies in rich broth, phosphate-limiting minimal salts medium, or human urine. Mutants complemented with the complete pst operon repressed AP synthesis in vitro and colonized the mouse bladder in numbers comparable to the wild-type strain HI4320. Therefore, the Pst transport system imparts a significant in vivo advantage to wild-type P. mirabilis that is not required for in vitro growth. Thus, the Pst transporter has satisfied molecular Koch's postulates as a virulence factor in the pathogenesis of urinary tract infection caused by P. mirabilis.
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Affiliation(s)
- Sandra M Jacobsen
- Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, Baltimore, MD, USA
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11
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C.2 Sonde à demeure– trans-urétrale/sus-pubienne. Prog Urol 2007. [DOI: 10.1016/s1166-7087(07)92358-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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12
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Sahu SN, Acharya S, Tuminaro H, Patel I, Dudley K, LeClerc JE, Cebula TA, Mukhopadhyay S. The bacterial adaptive response gene, barA, encodes a novel conserved histidine kinase regulatory switch for adaptation and modulation of metabolism in Escherichia coli. Mol Cell Biochem 2004; 253:167-77. [PMID: 14619967 DOI: 10.1023/a:1026028930203] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Histidine kinases are important prokaryotic determinants of cellular adaptation to environmental conditions, particularly stress. The highly conserved histidine kinase, BarA, encoded by the bacterial adaptive response gene, barA, is a member of the family of tripartite histidine kinases, and is involved in stress adaptation. BarA has been implicated to play a role during infection of epithelial cells. Homologues and orthologues of BarA have been found in pathogenic yeast, fungi, mould and in plants. The primary aim of this review is to assimilate evidence present in the current literature linking the role of BarA in stress response, and to support it with preliminary experimental evidence indicating that, it is indeed a global response regulator. In particular, the review focuses on the unusual domain structure of the BarA protein, its role in oxidative, weak acid, and osmotic stress responses and its role in biofilm formation. A preliminary genomic approach to identify downstream genes regulated by the BarA signaling pathway, using DNA microarray, is reported. The results demonstrate that BarA plays a global response regulatory role in cell division, carbon metabolism, iron metabolism and pili formation. The evolutionary significance of these types of histidine kinase sensors is reviewed in light of their roles in pathogenesis.
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Jones BV, Young R, Mahenthiralingam E, Stickler DJ. Ultrastructure of Proteus mirabilis swarmer cell rafts and role of swarming in catheter-associated urinary tract infection. Infect Immun 2004; 72:3941-50. [PMID: 15213138 PMCID: PMC427392 DOI: 10.1128/iai.72.7.3941-3950.2004] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteus mirabilis is a common cause of catheter-associated urinary tract infection (C-UTI). It blocks indwelling urethral catheters through the formation of extensive crystalline biofilms. The obstruction of urine flow can induce episodes of pyelonephritis, septicemia, and shock. P. mirabilis exhibits a type of motility referred to as swarming, in which multicellular rafts of elongated, hyperflagellated swarmer cells form and move rapidly in concert over solid surfaces. It has been suggested that swarming is important in the pathogenesis of C-UTI. In this study we generated a set of stable transposon mutants deficient in swarming and used them to assess the role of swarming in the migration of P. mirabilis over urinary catheters. Swarming was found to be essential for migration over all-silicone catheters. Swarming-deficient mutants were attenuated in migration over hydrogel-coated latex catheters, but those capable of swimming motility were able to move over and infect these surfaces. A novel vapor fixation technique for the preparation of specimens and scanning electron microscopy were used to resolve the ultrastructure of P. mirabilis multicellular rafts. The flagellar filaments of P. mirabilis were found to be highly organized during raft migration and were interwoven in phase to form helical connections between adjacent swarmer cells. Mutants lacking these novel organized structures failed to swarm successfully. We suggest that these structures are important for migration and formation of multicellular rafts. In addition, the highly organized structure of multicellular rafts enables P. mirabilis to initiate C-UTI by migration over catheter surfaces from the urethral meatus into the bladder.
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Affiliation(s)
- Brian V Jones
- Cardiff School of Biosciences, Cardiff University, Main Bldg., Rm. 1.53, Cardiff, Wales, United Kingdom CF10 3TL
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Abstract
Urinary catheter-related infections are commonly seen in several different patient populations and lead to substantial morbidity. The overall health care costs caused by these infections are sizable given how often urinary catheters are used in acute care settings, extended care facilities, and in persons with injured spinal cords. Recent attention has appropriately focused on biofilm development on the catheter surface because biofilm has important implications for the pathogenesis, treatment, and prevention of catheter-related infection. Because the most important risk factor for infection is duration of catheterization, indwelling urethral catheterization should be avoided or at least limited whenever possible. Additional methods to prevent this infection include aseptic insertion and maintenance use of a closed drainage system, anti-infective catheters in patients at high-risk for infection, and systemic antibiotics in select patients. Alternative urinary collection strategies may be appropriate in certain patient groups. Specifically, condom catheters should be considered in men likely to be adherent with this urinary collection method, suprapubic catheters should be considered in patients requiring long-term indwelling drainage, and intermittent catheterization seems appropriate in patients with injured spinal cords. Future research should focus on additional methods for preventing this common infection.
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Affiliation(s)
- Sanjay Saint
- Ann Arbor VA Medical Center, Ann Arbor, MI, USA.
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Abstract
Though biofilms were first described by Antonie van Leeuwenhoek, the theory describing the biofilm process was not developed until 1978. We now understand that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health. Using tools such as the scanning electron microscope and, more recently, the confocal laser scanning microscope, biofilm researchers now understand that biofilms are not unstructured, homogeneous deposits of cells and accumulated slime, but complex communities of surface-associated cells enclosed in a polymer matrix containing open water channels. Further studies have shown that the biofilm phenotype can be described in terms of the genes expressed by biofilm-associated cells. Microorganisms growing in a biofilm are highly resistant to antimicrobial agents by one or more mechanisms. Biofilm-associated microorganisms have been shown to be associated with several human diseases, such as native valve endocarditis and cystic fibrosis, and to colonize a wide variety of medical devices. Though epidemiologic evidence points to biofilms as a source of several infectious diseases, the exact mechanisms by which biofilm-associated microorganisms elicit disease are poorly understood. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could initiate the disease process. Effective strategies to prevent or control biofilms on medical devices must take into consideration the unique and tenacious nature of biofilms. Current intervention strategies are designed to prevent initial device colonization, minimize microbial cell attachment to the device, penetrate the biofilm matrix and kill the associated cells, or remove the device from the patient. In the future, treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.
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Affiliation(s)
- Rodney M Donlan
- Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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Walker JT, Verran J, Boyd RD, Percival S. Microscopy methods to investigate structure of potable water biofilms. Methods Enzymol 2001; 337:243-55. [PMID: 11398433 DOI: 10.1016/s0076-6879(01)37018-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- J T Walker
- Centre for Applied Microbiology and Research (CAMR), Porton Down, Salisbury SP4 0JG, United Kingdom
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Abstract
Biofilms can be defined as communities of microorganisms attached to a surface. It is clear that microorganisms undergo profound changes during their transition from planktonic (free-swimming) organisms to cells that are part of a complex, surface-attached community. These changes are reflected in the new phenotypic characteristics developed by biofilm bacteria and occur in response to a variety of environmental signals. Recent genetic and molecular approaches used to study bacterial and fungal biofilms have identified genes and regulatory circuits important for initial cell-surface interactions, biofilm maturation, and the return of biofilm microorganisms to a planktonic mode of growth. Studies to date suggest that the planktonic-biofilm transition is a complex and highly regulated process. The results reviewed in this article indicate that the formation of biofilms serves as a new model system for the study of microbial development.
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Affiliation(s)
- G O'Toole
- Department of Microbiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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18
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Abstract
Biofilms are complex communities of microorganisms attached to surfaces or associated with interfaces. Despite the focus of modern microbiology research on pure culture, planktonic (free-swimming) bacteria, it is now widely recognized that most bacteria found in natural, clinical, and industrial settings persist in association with surfaces. Furthermore, these microbial communities are often composed of multiple species that interact with each other and their environment. The determination of biofilm architecture, particularly the spatial arrangement of microcolonies (clusters of cells) relative to one another, has profound implications for the function of these complex communities. Numerous new experimental approaches and methodologies have been developed in order to explore metabolic interactions, phylogenetic groupings, and competition among members of the biofilm. To complement this broad view of biofilm ecology, individual organisms have been studied using molecular genetics in order to identify the genes required for biofilm development and to dissect the regulatory pathways that control the plankton-to-biofilm transition. These molecular genetic studies have led to the emergence of the concept of biofilm formation as a novel system for the study of bacterial development. The recent explosion in the field of biofilm research has led to exciting progress in the development of new technologies for studying these communities, advanced our understanding of the ecological significance of surface-attached bacteria, and provided new insights into the molecular genetic basis of biofilm development.
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Affiliation(s)
- M E Davey
- Department of Microbiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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Morris NS, Stickler DJ. Encrustation of indwelling urethral catheters by Proteus mirabilis biofilms growing in human urine. J Hosp Infect 1998; 39:227-34. [PMID: 9699143 DOI: 10.1016/s0195-6701(98)90262-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The encrustation and blockage of four types of urinary catheters was studied in a simple laboratory model of the catheterized bladder. Pooled human urine was supplied to the bladder chamber at 0.5 mL/min. The bladder urine was inoculated with a clinical strain of Proteus mirabilis that had been isolated from an encrusted catheter. The models were operated until the catheters blocked and atomic absorption spectrometry was used to assess the amounts of calcium and magnesium deposited on the catheters. Scanning electron microscopy was also used to locate and assess the degree of encrustation. All catheters blocked rapidly, the mean times to blockage ranging from 17.7 h (silver-coated latex), 34 h (hydrogel-coated latex), 38 h (silicone-coated latex) to 47 h (all silicone). The internal diameters of the latex catheters were only 1.5 mm compared to the 2.5 mm of the all-silicone catheters. The calcium and magnesium salts were deposited on the lumenal surfaces along the full length of catheters but occurred most extensively just below the eye-holes. There is clearly a need to develop catheter surfaces which resist encrustation by crystalline biofilms of P. mirabilis.
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Affiliation(s)
- N S Morris
- School of Pure and Applied Biology, University of Wales, Cardiff, UK
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20
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Høiby N, Giwercman B, Jensen ET, Pedersen SS, Koch C, Kharazmi A. Mechanism of action of antibiotics in chronic pulmonary pseudomonas infection. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1994; 30:53-84. [PMID: 7833297 DOI: 10.1016/s1054-3589(08)60172-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- N Høiby
- Department of Clinical Microbiology Danish Cystic Fibrosis Centre, Copenhagen, Denmark
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