Portal de Periódicos da CAPES

Biofilm: Its Relevance In Kidney Disease

2006; Elsevier BV; Volume: 13; Issue: 3 Linguagem: Inglês

10.1053/j.ackd.2006.04.002

1548-5609

Gino Tapia, Jerry Yee,

Bacterial biofilms and quorum sensing

Biofilm/bioslime is a complex, dynamically interactive multicellular community protected within a heterogeneous exopolysaccharide matrix. Its formation results in the genesis or perpetuation of infection, enhancement of inflammation, and tissue damage or death. Industrial financial losses result from biofilm/bioslime formation; however, the consequences in the medical realm are equally devastating. The relation of biofilm to patients with chronic kidney disease is often covert and extends beyond the colonization of hemodialysis circuits and vascular accesses. Urinary tract device– and vascular access–related biofilms may also increase the burden of cardiovascular risk borne by chronic kidney disease patients, synergizing with the chronic inflammatory state already incurred by these individuals. Current anti-infective strategies are aimed at rapidly killing planktonic forms of microorganisms without specifically targeting the sessile forms that perpetuate their planktonic brethren. Future treatments of infections must ultimately target these reservoirs of infection aiming for their complete eradication. Presently, included among these novel weapons of microdestruction are molecular blockading techniques, electrical enhancement of anti-infectives, and bacterial interference. Nonetheless, the best approach against biofilm formation remains the prevention of microbial colonization, which can be largely by sterile handling of patient-related devices, the most well-established biofilm reservoirs. Biofilm/bioslime is a complex, dynamically interactive multicellular community protected within a heterogeneous exopolysaccharide matrix. Its formation results in the genesis or perpetuation of infection, enhancement of inflammation, and tissue damage or death. Industrial financial losses result from biofilm/bioslime formation; however, the consequences in the medical realm are equally devastating. The relation of biofilm to patients with chronic kidney disease is often covert and extends beyond the colonization of hemodialysis circuits and vascular accesses. Urinary tract device– and vascular access–related biofilms may also increase the burden of cardiovascular risk borne by chronic kidney disease patients, synergizing with the chronic inflammatory state already incurred by these individuals. Current anti-infective strategies are aimed at rapidly killing planktonic forms of microorganisms without specifically targeting the sessile forms that perpetuate their planktonic brethren. Future treatments of infections must ultimately target these reservoirs of infection aiming for their complete eradication. Presently, included among these novel weapons of microdestruction are molecular blockading techniques, electrical enhancement of anti-infectives, and bacterial interference. Nonetheless, the best approach against biofilm formation remains the prevention of microbial colonization, which can be largely by sterile handling of patient-related devices, the most well-established biofilm reservoirs. Pathogenic organisms have withstood the onslaught of anti-infective therapies since their inception. The major reason for their persistence and ability to evolve is their commensal property of biofilm formation. Although the incidence of biofilm or bioslime formation remains unknown, these polymeric, genetically controlled communities of microorganisms adherent to surfaces, are estimated to cause at least 60% of bacterial infections in the developed world.1Costerton J.W. Bacterial biofilms A common cause of persistent infections.Science. 1999; 284: 1318-1322Crossref PubMed Scopus (9033) Google Scholar Accordingly, biofilm constitutes an alarmingly high proportion of infection-related medical costs, which in 2002, have been estimated at $6.7 billion by the Centers for Disease Control and Prevention.2Haley R.W. Incidence and nature of endemic and epidemic nosocomial infections.in: Brachman P. Hospital Infections. Little Brown, Boston, MA1985: 359-374Google Scholar Patients with chronic kidney disease incur a disproportionate share of infections and, therefore, are similarly at higher risk for biofilm formation. For example, direct charges for Staphylococcus aureus bacteremia in hemodialysis patients has been estimated at $24, 033 per episode.3Engemann J.J. Friedman J.Y. Reed S.D. et al.Clinical outcomes and costs due to Staphylococcus aureus bacteremia among patients receiving long-term hemodialysis.Infect Control Hosp Epidemiol. 2005; 26: 534-539Crossref PubMed Scopus (123) Google Scholar Moreover, biofilm represents a pathogenic force in the realm of peritoneal dialysis, kidney stone formers and any patient housing an indwelling medical device, particularly within the confines of an intensive care unit in which resident biofilms may become abundant. In addition, hemodialysis-dependent individuals are periodically exposed to a circuitry of tubes and sensors that may be contaminated by hardy biofilms. Presently, the accrual of the molecular underpinnings of biofilm formation is now bearing fruit. The conception and development of novel molecular and pharmacological treatment modalities that target not the intact pathogen per se, but the regulation and control of its biofilm-making machinery enhances the conventional approach of antimicrobial/antibiotic therapy and paves the way for improved therapy of all patients with infections. Biofilm is a sessile multicellular community comprised of an exopolysaccharide matrix embedded with living microorganisms that evolves to overcome local microenvironmental physical and chemical stressors. Bacterial adherence on inert and living surfaces plays an important role in the industrial, agricultural, and medical fields, often with highly damaging financial outcomes. Biofilm-mediated corrosion of water- and oil-carrying pipes, tubes, tanks, and reservoirs is a common industrial concern. The presence of biofilms within oil pipelines leads to corrosion of the internal pipe wall, and within industrial water systems they cause biofouling, the phenomenon whereby surfaces in contact with water are colonized by microorganisms, often with secondary accretion of local minerals, making the bioslime even less penetrable.4Choong S. Whitfield H. Biofilms and their role in infections in urology.BJU Int. 2000; 86: 935-941Crossref PubMed Google Scholar In water-distribution systems, biofilms degrade the safety and quality of drinking water. However, industry-ruinous organisms must first gain a foothold on inert surfaces before they unleash their uniquely damaging capabilities, one of which is altering the native galvanic currents on metallic surfaces to optimize their adherence. Several bacterial species can absorb nitrogen and sulfur from the atmosphere and/or their host metallic surfaces to produce structurally damaging nitric and sulfuric acids. The mining industry's leaching processes (mixing the ore with chemical in order to separate materials) also inadvertently support the growth of massive biofilm formation. Other industries similarly afflicted include those involving airplanes, papermaking, and oil distribution. In agriculture, the health of crops and livestock is compromised by biofilm. As an example, the xylem-clogging organism, Xylella fastidiosa, wreaks destruction on the grape industry without ever directly physically damaging the plant.5Meng Y. Li Y. Galvani C.D. et al.Upstream migration of Xylella fastidiosa via pilus-driven twitching motility.J Bacteriol. 2005; 187: 5560-5567Crossref PubMed Scopus (213) Google Scholar "Ring rot" by Clavibacter or Rhizobia species, on the other hand, directly infects its potato hosts, thereby killing them.6Fujishige N.A. Kapadia N.N. Hirsch A.M. Feeling for the micro-organism: Structure on a small scale. Biofilms on plant roots.Bot J Linn Soc. 2006; 150: 79-88Crossref Scopus (41) Google Scholar In medicine, biofilm is hypothesized to cause more than 60% of all infections.1Costerton J.W. Bacterial biofilms A common cause of persistent infections.Science. 1999; 284: 1318-1322Crossref PubMed Scopus (9033) Google Scholar Biofilm formations have a major impact on temporary and permanent implants or devices placed in the human body. Electron microscopic studies of infected medical devices have revealed heavy colonization and biofilm formation on such devices.7Anwar H. Dasgupta M.K. Costerton J.W. Testing the susceptibility of bacteria in biofilms to antibacterial agents.Antimicrob Agents Chemother. 1990; 34: 2043-2046Crossref PubMed Scopus (269) Google Scholar Endotracheal tubes, urinary catheters, pacemaker wires, and orthopedic joint replacements have all been inhabited by biofilms, with consequent infection. In dentistry, biofilms play an important role in the formation of dental plaque, which contributes to infection, tooth decay, and chronic gum disease such as inflammatory periodontal disease. Dental implants, braces, and bridges also represent ideal places for biofilms, bathed in an environment replete with commensal bacteria that possess the appropriate molecular machinery to stick to such prosthetics. Aside from these sources of biofilm, one must never forget that biofilms live within our own residences, on cutting boards, kitchen counters, and in toilets. Failure to cleanse such surfaces properly may contribute to infection, particularly in immunocompromised individuals or those with long-term indwelling urinary and vascular catheters for home-infusion therapies. Bacteria moor themselves to inert and tissue surfaces, particularly those that have been previously scored or roughened, via their fimbriae and pili (see Fig 1 of article by Lok in this issue). After adherence, these sessile forms reinforce their anchorage through their production of a "sticky" exopolymer. This polymer is composed primarily of exopolysaccharide and water, and its mass may be 100-fold larger than the microorganisms that it shelters. Production of this matrix precedes an initial growth phase that culminates in microcolony formation. Expansion of microcolonies and coalescence ultimately leads to a much larger, mature, heterogeneous, and multilayered biofilm, housing a biomass that can sustain itself with nutritive flow through multiple channels that also permits biological communication among the sessile form of microorganisms throughout the biofilm. From these sessile organisms, free-living or planktonic forms are derived that can multiply rapidly and disperse after programmed detachment from the host biofilm to produce acute infectivity. A more greatly detailed expository of the orchestration of the multiple steps in the biofilm life cycle follows using prototypical examples of several pathogenic species. Bacteria produce toxic exomolecules only when in higher densities (postexponential phase of growth). In early exponential growth, when at lower densities, the bacteria express surface molecules, such as fibronectin-binding proteins and fibrinogen-binding protein, facilitating their attachment per se to a central venous catheter with a fibrin sheath. These allow the organism to adhere to and colonize host cells.8Lowy F. Staphylococcus aureus infections.N Engl J Med. 1998; 339: 520-532Crossref PubMed Scopus (4667) Google Scholar For example, the ability of S aureus to differentially express surface adhesion molecules and toxin exomolecules is regulated primarily by RNAIII, encoded by the agr locus. Synthesis of RNAIII is regulated by quorum sensing, a process by which bacterial signaling molecules (autoinducers) are produced and secreted until a critical threshold concentration is reached and RNAIII is synthesized.9Balaban N. Goldkorn T. Gov Y. et al.Regulation of Staphylococcus aureus pathogenesis via target of RNAIII-activating protein (TRAP).J Biol Chem. 2001; 276: 2658-2667Crossref PubMed Scopus (128) Google Scholar On surface contact, bacteria such as Pseudomonas aeruginosa transcribe specific genes (algC, algD, and algU) to synthesize extracellular polysaccharides that increase there surfacial attachment.10Schauder S. Bassler B.L. The languages of bacteria.Genes Dev. 2001; 15: 1468-1480Crossref PubMed Scopus (377) Google Scholar Again via a quorum sensing regulatory process, when the resulting microcolony aggregates achieve critical density, autoinducer acylhomoserine lactones (AHL) encoded at the LasR-Lasl loci, are produced.10Schauder S. Bassler B.L. The languages of bacteria.Genes Dev. 2001; 15: 1468-1480Crossref PubMed Scopus (377) Google Scholar AHLs subsequently facilitate thickening of biofilm, establishment of intercellular signaling regarding cell-density relationships and production of virulence factors, with downstream cytokine regulation. Although the exact mechanisms of quorum sensing differ between gram-negative and gram-positive bacterial species, a commonality exists: quorum sensing regulates bacterial symbiosis, virulence, antimicrobial production, and biofilm formation and is a fertile field for innovative pharmacotherapeutics.10Schauder S. Bassler B.L. The languages of bacteria.Genes Dev. 2001; 15: 1468-1480Crossref PubMed Scopus (377) Google Scholar By their attachment to inert (eg, stone matrix) or biological surfaces (eg, mucosal scars), biofilms gain importance in kidney disease because of their promulgation of infections of the urinary tract, vascular accesses, central venous catheters, arteriovenous grafts, peritoneal catheters, dialysis circuits, and dedicated water systems.1Costerton J.W. Bacterial biofilms A common cause of persistent infections.Science. 1999; 284: 1318-1322Crossref PubMed Scopus (9033) Google Scholar, 7Anwar H. Dasgupta M.K. Costerton J.W. Testing the susceptibility of bacteria in biofilms to antibacterial agents.Antimicrob Agents Chemother. 1990; 34: 2043-2046Crossref PubMed Scopus (269) Google Scholar Moreover, the proinflammatory mediators emanating from biofilms may promulgate cardiovascular risk, enhance the chronic inflammatory state of chronic kidney disease, and worsen anemia management.11Ishani A. Collins A. Herzog C. et al.Septicemia, access and cardiovascular disease in dialysis patients The USRDS Wave 2 Study.Kidney Int. 2005; 68: 311-318Crossref PubMed Scopus (253) Google Scholar Bacteria and/or fungi can initiate biofilm formation on urinary catheters in 48 hours. When present on the surface of such a device, the escape of planktonic forms renders the patient susceptible to urosepsis. The subsequent incorporation of endogenously produced proteins such as coagulation proteins can enhance the growth of the biofilm and cosset the organisms from anti-infective therapy and eradication. Therefore, surveillance for urinary tract infections is paramount in individuals who require long-term catheterization. Chronic kidney disease may result from staghorn calculus formation, and struvite formation from urease producing bacteria is the principal pathogenetic event. However, the initiating event is the adherence of the inciting organism to a stone nidus, disrupted urothelium, or a foreign body, including urethral catheters, stents, and nephrostomy tubes in the renal parenchyma and/or bladder. Adherence is followed by colony formation and biofilm expansion, which now permits the organism to live on the stone that it has produced and continually reinfect the urine. Furthermore, the biofilm protects the organism from antibiotic/antimicrobial penetration12Nickel J.C. Reid G. Bruce A. et al.Ultrastructural microbiology of infected urinary stone.Urology. 1986; 28: 512-515Abstract Full Text PDF PubMed Scopus (30) Google Scholar and urine-acidifying therapy, as with Proteus mirabilis.13McLean R.J. Lawrence J.R. Korber D.R. et al.Proteus mirabilis biofilm protection against struvite crystal dissolution and its implications in struvite urolithiasis.J Urol. 1991; 146: 1138-1142PubMed Google Scholar Lastly, crystals entrapped in the biofilm matrix resist environmental pH changes and exhibit rapid structural growth aggravating the stone burden.13McLean R.J. Lawrence J.R. Korber D.R. et al.Proteus mirabilis biofilm protection against struvite crystal dissolution and its implications in struvite urolithiasis.J Urol. 1991; 146: 1138-1142PubMed Google Scholar Chronic urinary tract infections may also result from chronic prostatitis, and this too is a biofilm-related disorder. Evidence of the persistence of bacterial microcolonies or biofilms within the prostatic ducts or incorporated into corpora amylacea or calculi within the prostate permits long-term infection that becomes increasingly difficult to eradicate.14Nickel J.C. Prostatitis.in: Mulholland S.G. Antibiotic Therapy in Urology. Lippincott-Raven, Philadelphia, PA1996: 5-62Google Scholar In general, infections are the second leading cause of mortality among patients with end-stage renal disease. Many of these infections are caused by bacteremias that occur with a frequency of 1 per 100 patient-care months. The source of the infections is most often attributed to external skin-resident microbes gaining access to the blood space by migration along the external environs of a vascular access device, the consequence of which is an associated 3-month mortality of 19% to 34%.3Engemann J.J. Friedman J.Y. Reed S.D. et al.Clinical outcomes and costs due to Staphylococcus aureus bacteremia among patients receiving long-term hemodialysis.Infect Control Hosp Epidemiol. 2005; 26: 534-539Crossref PubMed Scopus (123) Google Scholar, 15Nassar G. Ayus J.C. Infectious complications of the hemodialysis access.Kidney Int. 2001; 60: 1-13Crossref PubMed Scopus (297) Google Scholar, 16Arduino M.J. Tokars J.I. Why is an infection control program needed in the hemodialysis setting?.Nephrol News Issues. 2005; 19: 46-49Google Scholar Hence, it is not surprising that staphyloccocal species account for 60% to 100% of episodes of catheter-related bloodstream infection in hemodialysis patients.3Engemann J.J. Friedman J.Y. Reed S.D. et al.Clinical outcomes and costs due to Staphylococcus aureus bacteremia among patients receiving long-term hemodialysis.Infect Control Hosp Epidemiol. 2005; 26: 534-539Crossref PubMed Scopus (123) Google Scholar, 15Nassar G. Ayus J.C. Infectious complications of the hemodialysis access.Kidney Int. 2001; 60: 1-13Crossref PubMed Scopus (297) Google Scholar Obviously, efforts should be made to create and maintain native arteriovenous fistulas that carry the lowest risk of infection among all vascular access modalities.15Nassar G. Ayus J.C. Infectious complications of the hemodialysis access.Kidney Int. 2001; 60: 1-13Crossref PubMed Scopus (297) Google Scholar, 16Arduino M.J. Tokars J.I. Why is an infection control program needed in the hemodialysis setting?.Nephrol News Issues. 2005; 19: 46-49Google Scholar On the other hand, bacteremias associated with indwelling vascular catheters predispose to the development of infective endocarditis in 2% to 6% percent of hemodialysis patients.17Khardori N. Yassien M. Biofilms in device-related infections devices.J Ind Microbiol. 1995; 3: 141-147Crossref Scopus (121) Google Scholar, 18Maraj S. Jacobs L.E. Maraj R. et al.Bacteremia and infective endocarditis in patients on hemodialysis.Am J Med Sci. 2004; 327: 242-249Crossref PubMed Scopus (27) Google Scholar Direct analysis of tissue vegetations reveals the existence of matrix-embedded microcolonies of bacteria.1Costerton J.W. Bacterial biofilms A common cause of persistent infections.Science. 1999; 284: 1318-1322Crossref PubMed Scopus (9033) Google Scholar Indeed, vegetations represent macroscopic bacterial biofilms.19Costerton W. Veeh R. Shirtliff M. et al.The application of biofilm science to the study and control of chronic bacterial infections.J Clin Invest. 2003; 112: 1466-1477Crossref PubMed Scopus (615) Google Scholar Bacteria can potentially initiate biofilm formation on the walls of urinary and vascular catheters within 48 hours of their placement, predisposing such patients to the development of sepsis from catheter-related infections.20Finkelstein E.S. Jekel J. Troidle L. et al.Patterns of infection in patients maintained on long-term peritoneal dialysis therapy with multiple episodes of peritonitis.Am J Kidney Dis. 2002; 39: 1278-1286Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar However, simple colonization is necessary but not sufficient to produce catheter-related bloodstream infection. Planktonic forms of the pathogen must be present and "break" free from the biofilm to induce bacteremia and/or sepsis.21Raad I.I. Costerton W. Sabharwal U. et al.Ultrastructural analysis of indwelling vascular catheters A quantitative relationship between luminal colonization and duration of placement.J Infect Dis. 1993; 168: 400-407Crossref PubMed Scopus (477) Google Scholar This observation correlates directly with the finding that just 11% of organisms can be cultured from indwelling central venous catheters that harbor biofilms.21Raad I.I. Costerton W. Sabharwal U. et al.Ultrastructural analysis of indwelling vascular catheters A quantitative relationship between luminal colonization and duration of placement.J Infect Dis. 1993; 168: 400-407Crossref PubMed Scopus (477) Google Scholar Furthermore, flow stagnation in venous catheters or a biosynthetic arteriovenous graft, from whichever cause, offers an ideal environment in which immobilized bacteria can proliferate and expand their biomass.22Cappelli G. Tetta C. Canaud B. Is biofilm a cause of silent chronic inflammation in hemodialysis patients? A fascinating working hypothesis.Nephrol Dial Transplant. 2005; 20: 266-270Crossref PubMed Scopus (41) Google Scholar Therefore, hemodialysis catheter dysfunction manifested by diminishing forward flows facilitates biofilm formation. Peritoneal catheter-related infections (exit-site infections, tunnel infections, and peritonitis) are mostly associated with technique failures with continuous ambulatory peritoneal dialysis.23Thodis E. Passadakis P. Peritoneal catheters and related infections.Int Urol Nephrol. 2005; 37: 379-393Crossref PubMed Scopus (28) Google Scholar As with all long-term medical devices, peritoneal catheters frequently acquire bacterial biofilm, thereby inducing the aforementioned infectious complications and their recurrence. This proposal has been shown in an analysis of 32 Tenckhoff peritoneal dialysis catheters from patients with peritonitis. Here, viable mixed microbial biofilms were present on 81% of catheters analyzed.24Gorman S.P. Adair C.G. Mawhinney W.M. Incidence and nature of peritoneal catheter biofilm determined by electron and confocal laser scanning microscopy.Epidemiol Infect. 1994; 112: 551-559Crossref PubMed Scopus (36) Google Scholar Moreover, the influence of deposition of extracellular matrix and coagulation protein agglomeration was shown in a case in which disruption of biofilm by tissue plasminogen activator led to resolution of a recurrent catheter-related peritonitis25Duch J. Yee J. Successful use of recombinant tissue plasminogen activator in a patient with relapsing peritonitis.Am J Kidney Dis. 2001; 37: 149-153Abstract Full Text PDF PubMed Scopus (24) Google Scholar; the authors expanded on a prior observation wherein heparin had yielded a similarly efficacious outcome. Hemodialysis water systems have been fouled by biofilm. Affected sites have included, paradoxically enough, the water treatment system itself, hydraulic monitors, and water distribution pipelines. Part of the problem has been attributed to the favorable environment sought by contaminating water-borne bacteria (ie, the organic nutrient content and high pH of commonly used bicarbonate-buffered solutions). In addition, physical factors, such as dead ends, low fluxes, and "stop flow" intervals, may favor biofilm formation.26Man N.K. Degremont A. Derbord J.C. et al.Evidence of bacterial biofilm in tubing from hydraulic pathway of hemodialysis system.Artif Organs. 1998; 22: 596-600Crossref PubMed Scopus (66) Google Scholar, 27Cappelli G. Ballestri M. Perrone S. et al.Biofilms invade nephrology Effects in hemodialysis.Blood Purif. 2000; 18: 224-230Crossref PubMed Scopus (38) Google Scholar However, the highest risk area for bacterial contamination likely derives from the water tubing that connects to the reverse osmosis-water distribution loop with the individual hemodialysis monitors.28Cappelli G. Ravera F. Ricardi M. et al.Water treatment for hemodialysis A 2005 update.Contrib Nephrol. 2005; 149: 42-50Crossref PubMed Scopus (8) Google Scholar Unfortunately, bacteria- and endotoxin-free dialysate does not exclude the risks and hazards of bacteria and endotoxin discharge from preexistent biofilm in fluid pathway tubing, serving as a continuous contaminatorium from which both bacteria and algae have been isolated.26Man N.K. Degremont A. Derbord J.C. et al.Evidence of bacterial biofilm in tubing from hydraulic pathway of hemodialysis system.Artif Organs. 1998; 22: 596-600Crossref PubMed Scopus (66) Google Scholar A multimodal plan of attack that thwarts biofilm formation within the silicone tubing of dialysis machines ought to include the following: direct microscopic observation for biofilm formation, biofilm removal with a mechanical scraping device, quantitative analysis with culturable and total bacteria counts, and endotoxin level measurement.29Marion-Ferey K. Enkiri F. Pasmore M. et al.Methods for biofilm analysis on silicone tubing of dialysis machines.Artif Organs. 2003; 27: 658-664Crossref PubMed Google Scholar In summary, biofilm formation represents the starting point for biofouling and resistance to disinfection and bacterial regrowth.30Stewart P.S. Costerton J.W. Antibiotic resistance of bacteria in biofilms.Lancet. 2001; 358: 135-138Abstract Full Text Full Text PDF PubMed Scopus (3377) Google Scholar Its residence within the hydraulic dialysis circuit consequently modifies the efficacy of differential disinfection modalities against bacteria and endotoxin concentrations.31Cappelli G. Effects of biofilm formation on hemodialysis monitor disinfection.Nephrol Dial Transplant. 2003; 18: 2105-2111Crossref PubMed Scopus (29) Google Scholar Recurrent bacteremias that originate from biofilm bacterial colonization has been associated with an approximately 2-fold increase in the risk of myocardial infarctions, stroke, heart failure, and peripheral vascular disease.11Ishani A. Collins A. Herzog C. et al.Septicemia, access and cardiovascular disease in dialysis patients The USRDS Wave 2 Study.Kidney Int. 2005; 68: 311-318Crossref PubMed Scopus (253) Google Scholar Therefore, bioslime represents an ongoing source of chronic, subclinical inflammation resulting from repetitive cycles of the release of noxious proinflammatory cytokines derived from monocytes/macrophage stimulation. This pathophysiological sequence potentially explains some the isolated febrile responses that occur during hemodialysis sessions in patients who have no obvious cause for infection.20Finkelstein E.S. Jekel J. Troidle L. et al.Patterns of infection in patients maintained on long-term peritoneal dialysis therapy with multiple episodes of peritonitis.Am J Kidney Dis. 2002; 39: 1278-1286Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar, 32Canaud B. Senecal L. Leray-Moragues H. et al.Vascular access, an underestimated cause of inflammation in hemodialysis patient.Nephrologie. 2003; 24: 353-358PubMed Google Scholar In patients with catheters, flow turbulence and shear forces within and around the catheter blood ingress and egress sites may convert sessile organisms into planktonic ones. The cytokine release from biofilms during dialytic and interdialytic intervals may also favor coagulation pathway activation, thereby enhancing the probability for vascular access thrombosis and erythropoietin resistance.20Finkelstein E.S. Jekel J. Troidle L. et al.Patterns of infection in patients maintained on long-term peritoneal dialysis therapy with multiple episodes of peritonitis.Am J Kidney Dis. 2002; 39: 1278-1286Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar In clinical studies regarding the anemia of end-stage renal disease, vascular access infections have been shown to increase the dose requirement of erythropoietin.33Tricia L. Obrador G. St. Peter W. et al.Relationship among catheter insertions, vascular access infections, and anemia management in hemodialysis patients.Kidney Int. 2004; 66: 2429-2436Crossref PubMed Scopus (56) Google Scholar No method presently exists that detects biofilm in vivo with sufficient sensitivity to confirm its eradication (ie, direct bright field microscopy). More highly sensitive techniques (eg, confocal microscopy) remain relegated to the research laboratory and cannot be used practically on a widespread scale in the clinical realm. In vascular access catheters that have been removed, surface ultrastructural analysis alone or in combination with specific staining techniques that detect bacterial nuclear DNA with membrane-permeable or -impermeable fluorochromes has disclosed the presence of microorganisms thriving within their glycocalyx cocoon.20Finkelstein E.S. Jekel J. Troidle L. et al.Patterns of infection in patients maintained on long-term peritoneal dialysis therapy with multiple episodes of peritonitis.Am J Kidney Dis. 2002; 39: 1278-1286Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar However, an indirect assay that detects viable organisms via endotoxin level measurement with chromogenic kinetic assays may provide a more efficient and practically-based assay for uncovering microorganisms resident within biofilm.34Marion F.K. Enkiri F. Pasmore M. et al.Methods for biofilm analysis on silicone tubing of dialysis machines.Artif Organs. 2003; 27: 658-664Crossref PubMed Scopus (18) Google Scholar Bacterial biofilms show adaptive resistance in response to antimicrobial stress more effectively than corresponding purely planktonic p