Is biofilm a cause of silent chronic inflammation in haemodialysis patients? A fascinating working hypothesis

A review on antimicrobial strategies in mitigating biofilm-associated infections on medical implants

Biomedical implants are crucial in providing support and functionality to patients with missing or defective body parts. However, implants carry an inherent risk of bacterial infections that are biofilm-associated and lead to significant complications. These infections often result in implant failure, requiring replacement by surgical restoration. Given these complications, it is crucial to study the biofilm formation mechanism on various biomedical implants that will help prevent implant failures. Therefore, this comprehensive review explores various types of implants (e.g., dental implant, orthopedic implant, tracheal stent, breast implant, central venous catheter, cochlear implant, urinary catheter, intraocular lens, and heart valve) and medical devices (hemodialyzer and pacemaker) in use. In addition, the mechanism of biofilm formation on those implants, and their pathogenesis were discussed. Furthermore, this article critically reviews various approaches in combating implant-associated infections, with a special emphasis on novel non-antibiotic alternatives to mitigate biofilm infections.

Biofilm-derived oxylipin 10-HOME-mediated immune response in women with breast implants

This study investigates a mechanistic link of bacterial biofilm-mediated host-pathogen interaction leading to immunological complications associated with breast implant illness (BII). Over 10 million women worldwide have breast implants. In recent years, women have described a constellation of immunological symptoms believed to be related to their breast implants. We report that periprosthetic breast tissue of participants with symptoms associated with BII had increased abundance of biofilm and biofilm-derived oxylipin 10-HOME compared with participants with implants who are without symptoms (non-BII) and participants without implants. S. epidermidis biofilm was observed to be higher in the BII group compared with the non-BII group and the normal tissue group. Oxylipin 10-HOME was found to be immunogenically capable of polarizing naive CD4+ T cells with a resulting Th1 subtype in vitro and in vivo. Consistently, an abundance of CD4+Th1 subtype was observed in the periprosthetic breast tissue and blood of people in the BII group. Mice injected with 10-HOME also had increased Th1 subtype in their blood, akin to patients with BII, and demonstrated fatigue-like symptoms. The identification of an oxylipin-mediated mechanism of immune activation induced by local bacterial biofilm provides insight into the possible pathogenesis of the implant-associated immune symptoms of BII.

Diabetic Peripheral Neuropathy Associated with Foot Ulcer: One of a Kind

Significance: Diabetic peripheral neuropathy (DPN) associated with a diabetic foot ulcer (DFU) is likely to be complicated with critical factors such as biofilm infection and compromised skin barrier function of the diabetic skin. Repaired skin with a history of biofilm infection is known to be compromised in barrier function. Loss of barrier function is also observed in the oxidative stress affected diabetic and aged skin. Recent Advances: Loss of barrier function makes the skin prone to biofilm infection and cellulitis, which contributes to chronic inflammation and vasculopathy. Hyperglycemia favors biofilm formation as glucose lowering led to reduction in biofilm development. While vasculopathy limits oxygen supply, the O2 cost of inflammation is high increasing hypoxia severity. Critical Issues: The host nervous system can be inhabited by bacteria. Because electrical impulses are a part of microbial physiology, polymicrobial colonization of the host's neural circuit is likely to influence transmission of action potential. The identification of perineural apatite in diabetic patients with peripheral neuropathy suggests bacterial involvement. DPN starts in both feet at the same time. Future Directions: Pair-matched studies of DPN in the foot affected with DFU (i.e., DFU-DPN) compared with DPN in the without ulcer, and intact skin barrier function, are likely to provide critical insight that would help inform effective care strategies. This review characterizes DFU-DPN from a translational science point of view presenting a new paradigm that recognizes the current literature in the context of factors that are unique to DFU-DPN.

Quality of dialysis water and dialysate in hemodialysis centers: highlight for occurrence of non-fermenting gram-negative bacilli

AIMS

To evaluate the physicochemical and microbiological quality of dialysis water and dialysate samples from hemodialysis centers.

METHODS AND RESULTS

Samples were fortnightly collected from three hemodialysis centers in Bauru City, Brazil, between July/2017 and June/2018, at the stages of post-reverse osmosis, reuse and dialysate. Analyses included determination of conductivity, fluoride, nitrate and sulfate; test for total coliform bacteria; count of heterotrophic bacteria; count and identification of non-fermenting gram-negative bacilli (NFGNB); drug susceptibility test; biofilm formation capacity, and genetic similarity among some isolated NFGNB. Of the analyzed samples, only 4/72 (5.6%) had conductivity values ≥ 10 mS/cm, 4/216 (1.9%) presented total coliforms, and 1/216 (0.5%) had heterotrophic bacteria count > 100 CFU/mL. NFGNB were isolated from 99/216 (45.8%) samples, and the major identified microorganisms included Herbaspirillum aquaticum/huttiense, Brevundimonas aurantiaca, Cupriavidus metallidurans, Pseudomonas aeruginosa and Ralstonia insidiosa. Isolates of P. aeruginosa and Burkholderia cepacia complex were sensitive to most antimicrobials and, together with isolates of Ralstonia insidiosa and Ralstonia pickettii, showed strong biofilm formation capacity. Some isolates expressed the same electrophoretic profile on pulsed-field gel electrophoresis, indicating persistence of bacterial clones in the systems over time.

CONCLUSIONS

NFGNB were observed in several dialysis water and dialysate samples from all investigated centers, which may represent a risk to the health of patients.

SIGNIFICANCE AND IMPACT OF THE STUDY

Regular inclusion of actions for NFGNB control and monitoring in hemodialysis fluids are suggested for greater safety of the dialytic process.

Soluble Triggering Receptor on Myeloid Cell-1 and its Predictive Factors in Patients With End-Stage Kidney Disease on Hemodialysis

Triggering receptor expressed on myeloid cells (TREM)-1 is a potent and early amplifier of the inflammatory response expressed on neutrophils and monocytes/macrophages. TREM-1, and its soluble form (sTREM-1), are increased in sepsis and other noninfectious inflammatory conditions. However, virtually no data are available in kidney disease. To determine serum sTREM-1 and its associated variables in patients on hemodialysis (HD), cross-sectional study including 264 HD patients and 148 controls. sTREM-1 was measured by quantitative sandwich enzyme immunoassay; soluble tumor necrosis factor receptor-1 (sTNF-R1), interleukin-6 (IL-6), and C-reactive protein (CRP) were also measured. All inflammation markers were significantly higher in HD patients than controls. Median (IQR) sTREM-1 was 1,006 (613-1,650) pg/mL but undetectable in controls. Considering only HD patients, sTREM-1 was positively correlated with IL-6 (r = 0.19, p = 0.008), and its levels were significantly higher in patients with arteriovenous fistula than in those with temporary catheter (1,226 vs. 743 pg/mL), in patients with 3 HD sessions/week than in those with 2 sessions/week (1,150 vs. 646 pg/mL), and in patients with >1 year on HD than in those with ≤1 year (1,100 vs. 948 pg/mL), whereas they were not different regarding age or presence of infection. Serum sTREM-1, sTNF-R1, IL-6, and CRP were higher in HD patients compared to controls. In HD patients, sTREM-1 displayed higher levels in individuals with arteriovenous fistula, 3 sessions/week and longer vintage, but not in those with infection or older age; in multivariate analysis, only the first two variables significantly predicted higher sTREM-1 levels.

Starting Hemodialysis with Catheter and Mortality Risk: Persistent Association in a Competing Risk Analysis

Purpose

The vascular access (VA) used at hemodialysis (HD) inception is involved in the mortality risk. We analyzed the survival of incident patients over time according to the initial VA and the VA profile of patients who died during the first year of follow-up.

Methods

Data of VA were obtained from 9956 incident HD patients from the Catalan Registry.

Results

Over 12 years, 47.9% of patients initiated HD with a fístula, 1.2% with a graft, 15.9% with a tunneled catheter and 35% with an untunneled catheter. Regarding fistula use, the hazard ratio of death for all-causes over time when applying a multivariate competing risk model was 1.55 [95% confidence interval (CI): 1.42-1.69] and 1.43 (95% CI: 1.33-1.54) for patients with tunneled and untunneled catheter, respectively. During the first year of follow-up, the crude all-cause mortality rate (deaths/100 patient-years) was higher during the early (first 120 days) compared to the late (121-365 days) period: 18.3 (95% CI: 16.8-19.8) versus 15.4 (95% CI: 14.5-16.5). Regarding fistula use, for patients using untunneled and tunneled catheter, the odds ratio of death in the early period for all-causes was 3.66 (95% CI: 2.80-4.81) and 2.97 (95% CI: 2.17-4.06), for cardiovascular causes it was 2.76 (95% CI: 1.90-4.01) and 1.84 (95% CI: 1.17-2.89) and for infection-related causes it was 6.62 (95% CI: 3.11-14.05) and 4.58 (95% CI: 2.00-10.52), respectively.

Conclusions

Half of all incident patients in Catalonia are exposed to excessive mortality risk related to catheter and this scenario can be improved by early fistula placement.

Cathasept Line Lock and Microbial Colonization of Tunneled Hemodialysis Catheters: A Multicenter Randomized Controlled Trial

BACKGROUND

Catheter-related bloodstream infections (CRBSIs) cause morbidity and mortality in hemodialysis (HD) patients. Cathasept (tetra-sodium EDTA) solution has antimicrobial and anticoagulant activities.

STUDY DESIGN

Multicenter prospective randomized controlled study.

SETTING & PARTICIPANTS

117 maintenance HD patients with confirmed uncolonized tunneled HD catheters from 4 HD centers.

INTERVENTION

Patients were randomly assigned to receive Cathasept 4% locks (Cathasept group) or stayed with heparin 5,000 U/mL locks (heparin group), filled thrice weekly according to catheter lumen volume until the catheter was removed or for a maximum of 8 months.

OUTCOMES

Primary outcome was clinically significant microbial colonization of the catheter, defined as a through-catheter quantitative blood culture yielding ≥ 1,000 colony-forming units/mL of bacteria or yeast. Secondary outcomes included CRBSI rate, catheter patency, and biomarkers of inflammation and anemia.

MEASUREMENTS

Weekly through-catheter quantitative blood culture, high-sensitivity C-reactive protein fortnightly, and full blood count and ferritin monthly.

RESULTS

Incidence rates of catheter colonization were 0.14/1,000 catheter-days in the Cathasept group and 1.08/1,000 catheter-days in the heparin group (incidence rate ratio [IRR], 0.13; 95% CI, 0.003-0.94; P=0.02). CRBSI rates were 0.28/1,000 catheter-days in the Cathasept group and 0.68/1,000 catheter days in the heparin group (IRR, 0.40; 95% CI, 0.08-2.09; P=0.3). The proportion of dialysis sessions with achieved prescribed blood flow rate was significantly lower in the Cathasept group (66.8% vs 75.3%; P<0.001), with more patients requiring thrombolytic locks or infusions to maintain catheter patency (22 vs 9; P=0.01). Mean high-sensitivity C-reactive protein level was 11.6±5.3 (SE) mg/L lower for patients in the heparin group (P=0.03). Anemia marker levels were similar in both groups.

LIMITATIONS

Study was underpowered to assess effect on CRBSI, terminated early due to slow recruitment, and not double blinded.

CONCLUSIONS

Cathasept significantly reduced tunneled hemodialysis catheter colonization, but the reduction in CRBSIs was not statistically significant, and it was associated with more thrombotic complications. Its safety profile was comparable to heparin lock solution.

An intradialytic increase in serum interleukin-6 levels is associated with an increased mortality in hemodialysis patients

BACKGROUND

The inflammatory marker interleukin-6 (IL-6) increases early in the inflammatory cascade. The aim of this study was to evaluate whether an increase in serum IL-6 levels during a hemodialysis (HD) session is associated with mortality.

METHODS

57 adult patients treated with HD for more than 1 month were prospectively studied over a 3-year follow-up period. Demographic and clinical data were collected and blood samples were drawn before and after a midweek HD session. Events of death and censoring were recorded.

RESULTS

During the 3-year follow-up, 50.8% of the patients died. In univariate Cox regression analysis, an increase in IL-6 levels during HD was associated with an increased mortality (HR 1.41 per pg/ml; 95% CI 1.06 to 1.88; P = .017). In multivariate Cox models, the only independent predictors of all-cause mortality were: an increase in IL-6 levels during dialysis (HR 1.46 per pg/ml; 95% CI 1.08 to 1.98; P = .014), higher baseline C-reactive protein (CRP) levels and older age. When predictors of an increase in serum IL-6 levels during HD were introduced into the model, mortality was still significantly associated with IL-6 elevation during dialysis (HR 1.47 per pg/ml, 95% CI 1.01 to 2.14; P = .045).

CONCLUSIONS

A rise in serum IL-6 levels during a single HD session is associated with a higher mortality among HD patients, independent of predialysis CRP or IL-6 levels. The results may imply the presence of an intradialytic inflammatory response that affects survival in HD patients.

Clinical Biofilms: A Challenging Frontier in Wound Care

Significance: Biofilms have been implicated in a variety of wound complications. Recent Advances: Research has confirmed that biofilms form in wounds of patients experiencing delayed healing and may be a precursor to infection. Critical Issues: Research into the strength of this association is still in its infancy. Is biofilm formation a cause of these complications, a step toward them, or a signal that unresolved factors injuring tissue or delaying healing are setting the stage for biofilm formation, infection, and healing delay? To qualify biofilms for use in informing clinical practice decisions, biofilm characteristics supporting those decisions need standardized definitions and valid evidence that they predict or diagnose healing or infection outcomes. Literature searches of relevant terms reviewed biofilm definitions and validation of their role in predicting and diagnosing delayed wound healing or infection. Future Directions: Further research is needed to provide a rapid accurate technique to identify and characterize biofilms in ways that optimize their validity in diagnosing or screening patient risk of infection or delayed healing and to inform clinical decisions. This research will help validate biofilm's capacity to support wound care clinical practice decisions and establish their importance in guiding clinical practice.

Dialysis patients and cardiovascular problems: can technology solve the complex equation?

Patients with end-stage kidney disease undergoing chronic hemodialysis present higher mortality rates compared with the general population. Once patients are on hemodialysis, the risk of cardiovascular death is approximately 30-times higher than the general population, and still remains 10- to 20-times higher after stratification for age, gender and presence of diabetes. Approximately half of patient deaths on dialysis are attributed to cardiovascular causes, including coronary heart disease, cerebrovascular disease, peripheral vascular disease and heart failure. The cardiovascular burden of the hemodialysis patient arises from three different sources: risks inherent to the patient and the uremic syndrome, traditional risk factors and risk factors related to the dialysis therapy. Based on these considerations and the fact that several aspects of the dialysis procedure can cause either a cardiovascular burden or modify the burden already present, new technologies should be directed towards the approach of a possible 'cardioprotective dialysis therapy'. This approach may significantly contribute new techniques and new dialysis machines. Born to make dialysis easy and safe, the new machines feature several options that make monitoring and online hemodiafiltration a simple routine. These and other features could make dialysis better tolerated and more efficient in protecting from fatal cardiovascular events.

Pretransplantation erythropoiesis-stimulating agent hyporesponsiveness is associated with increased kidney allograft failure and mortality

BACKGROUND

Poor response to erythropoiesis-stimulating agents (ESA) is associated with morbidity and mortality among dialysis patients. It is unclear whether the risk associated with poor ESA response during dialysis extends beyond kidney transplantation. We examined pretransplantation ESA response and its effect on allograft failure and mortality.

METHODS

The cohort included all adult Medicare recipients from the U.S. Renal Data System who had received a kidney transplant during years 2000 to 2007 and had at least 6 months of hemodialysis immediately before transplantation. ESA hyporesponsiveness was primarily defined as a monthly ESA dose of 75,000 units or higher and hematocrit 33% or less for at least 3 consecutive months in the pretransplantation period. Crude and adjusted Cox proportional hazards models and Kaplan-Meier methods were used to estimate the effect of ESA hyporesponsiveness on allograft failure and all-cause mortality.

RESULTS

The study group consisted of 36,450 patients; 1004 exhibited hyporesponsiveness. The adjusted hazard ratios (95% confidence interval) for allograft failure and mortality after transplantation were 1.23 (1.10-1.42) and 1.61 (1.43-1.81), respectively, supporting that poor ESA response during hemodialysis is associated with adverse posttransplantation outcomes.

CONCLUSIONS

ESA hyporesponsiveness may be useful in identifying potential allograft recipients who are at high risk for subsequent morbidity and mortality and may benefit from more intensive pretransplantation and posttransplantation monitoring.

Histopathological analysis of Salmonella chronic carriage in the mouse hepatopancreatobiliary system

Salmonella Typhi asymptomatic chronic carriage represents a challenge for the diagnosis and prevention of typhoid fever in endemic areas. Such carriers are thought to be reservoirs for further spread of the disease. Gallbladder carriage has been demonstrated to be mediated by biofilm formation on gallstones and by intracellular persistence in the gallbladder epithelium of mice. In addition, both gallstones and chronic carriage have been associated with chronic inflammation and the development of gallbladder carcinoma. However, the pathogenic relationship between typhoid carriage and the development of pre-malignant and/or malignant lesions in the hepatopancreatobiliary system as well as the host-pathogen interactions occurring during chronic carriage remains unclear. In this study, we monitored the histopathological features of chronic carriage up to 1 year post-infection. Chronic cholecystitis and hepatitis ranging from mild to severe were present in infected mice regardless of the presence of gallstones. Biliary epithelial hyperplasia was observed more commonly in the gallbladder of mice with gallstones (uninfected or infected). However, pre-malignant lesions, atypical hyperplasia and metaplasia of the gallbladder and exocrine pancreas, respectively, were only associated with chronic Salmonella carriage. This study has implications regarding the role of Salmonella chronic infection and inflammation in the development of pre-malignant lesions in the epithelium of the gallbladder and pancreas that could lead to oncogenesis.

Identification of Salmonella enterica serovar Typhimurium genes regulated during biofilm formation on cholesterol gallstone surfaces

Salmonella spp. are able to form biofilms on abiotic and biotic surfaces. In vivo studies in our laboratory have shown that Salmonella can form biofilms on the surfaces of cholesterol gallstones in the gallbladders of mice and human carriers. Biofilm formation on gallstones has been demonstrated to be a mechanism of persistence. The purpose of this work was to identify and evaluate Salmonella sp. cholesterol-dependent biofilm factors. Differential gene expression analysis between biofilms on glass or cholesterol-coated surfaces and subsequent quantitative real-time PCR (qRT-PCR) revealed that type 1 fimbria structural genes and a gene encoding a putative outer membrane protein (ycfR) were specifically upregulated in Salmonella enterica serovar Typhimurium biofilms grown on cholesterol-coated surfaces. Spatiotemporal expression of ycfR and FimA verified their regulation during biofilm development on cholesterol-coated surfaces. Surprisingly, confocal and scanning electron microscopy demonstrated that a mutant of type 1 fimbria structural genes (ΔfimAICDHF) and a ycfR mutant showed increased biofilm formation on cholesterol-coated surfaces. In vivo experiments using Nramp1(+/+) mice harboring gallstones showed that only the ΔycfR mutant formed extensive biofilms on mouse gallstones at 7 and 21 days postinfection; ΔfimAICDHF was not observed on gallstone surfaces after the 7-day-postinfection time point. These data suggest that in Salmonella spp., wild-type type 1 fimbriae are important for attachment to and/or persistence on gallstones at later points of chronic infection, whereas YcfR may represent a specific potential natural inhibitor of initial biofilm formation on gallstones.

Catheter-related infections in chronic hemodialysis: a clinical and economic perspective

PURPOSE

Central venous catheters emerged as a major risk factor for infectious complications in hemodialysis (HD) patients. We aimed to assess the incidence of bacteremia in catheter-dependent HD patients and to characterize its clinical and economic impact.

METHODS

We retrospectively collected clinical data and healthcare costs from 15 months for 75 admitted catheter-dependent HD patients, to document the type of bacteremia (complicated or not), pathogen and inflammation.

RESULTS

Bacteremia (97 % with Staphylococcus aureus, 33 % methicillin-resistant) was present in 51 % patients, with an overall infections incidence of 5.79 per 1,000 catheter-days. Metastatic complications occurred in 21 % of bacteremic patients and were associated with higher mortality (38 vs. 4 %; p = 0.001). Although, in patients starting dialysis on catheter (41 %) as compared to those using catheter as bridge angioaccess, inflammation (higher C-reactive protein; p = 0.006) and anemia (lower Hb; p = 0.008) were more pronounced, bacteremia occurred in a lower proportion (32 vs. 64 %, p = 0.007). The total medical costs were 47 % higher in patients with complicated bacteremia than in those without bacteremia (p = 0.008) and 45 % higher in patients starting HD on catheter than in those using catheter as bridge angioaccess (p = 0.002).

CONCLUSIONS

Despite the limitations resulting from retrospective cross-sectional single-center design, our study suggests that patients already on HD who required catheters as bridge angioaccess were more prone to bacteremia. This highlights the importance of close angioaccess monitoring to avoid unnecessary catheter usage. A similar increase in costs when initiating dialysis on catheter as in case of complicated bacteremia strongly supports the initial placement of a native arteriovenous fistula.

Changes in inflammatory markers during a hemodialysis session and their relation to vascular access type

PURPOSE

In an attempt to better understand the relationship between vascular access and inflammation we assessed the effect of vascular access on inflammatory markers changes during hemodialysis (HD) session.

METHODS

Fifty HD patients were included: 23 patients with central venous catheters (CVC) and 27 patients with arteriovenous fistulas (AVF). Blood samples for high sensitivity C-reactive protein (hsCRP), Interleukin 6 (IL-6), and Tumor Necrosis Factor α (TNF α) were collected before and after HD session. The outcome was the change in the inflammatory markers during the dialysis.

RESULTS

Predialysis hsCRP levels were high in 70% of patients, without differences between the groups. Predialysis values were also similar in the two groups for IL-6 and TNF α. There was no increase in hsCRP values following HD and no difference between the change from baseline values in the CVC and AVF groups (-0.01±0.09 mg/dL and -0.01±0.13 mg/dL, respectively [P=.95]). IL-6 values increased during the HD session in the AVF group and non-significantly decreased in the CVC group. The change from baseline values was statistically significantly greater in the AVF group compared to the CVC group (0.76±1.44 ng/mL and -0.52±1.66 ng/mL, respectively, P=.006). TNF α values were significantly decreased in the CVC group and were not changed in the AVF group. The decrease from baseline values was not different between the groups.

CONCLUSIONS

Chronic inflammation is present in most HD patients. No increase in pro-inflammatory parameters was seen after a HD session in patients treated via CVC or AVF.

Candida parapsilosis complex water isolates from a haemodialysis unit: biofilm production and in vitro evaluation of the use of clinical antifungals

Candida parapsilosis, currently divided into three distinct species, proliferates in glucose-rich solutions and has been associated with infections resulting from the use of medical devices made of plastic, an environment common in dialysis centres. The aims of this study were (i) to screen for Candida orthopsilosis and Candida metapsilosis (100 environmental isolates previously identified as C. parapsilosis), (ii) to test the ability of these isolates to form biofilm and (iii) to investigate the in vitro susceptibility of Candida spp biofilms to the antifungal agents, fluconazole (FLC) and amphotericin B (AMB). Isolates were obtained from a hydraulic circuit collected from a haemodialysis unit. Based on molecular criteria, 47 strains were re-identified as C. orthopsilosis and 53 as C. parapsilosis. Analyses using a formazan salt reduction assay and total viable count, together with microscopy studies, revealed that 72 strains were able to form biofilm that was structurally similar, but with minor differences in morphology. A microtitre-based colorimetric assay used to test the susceptibility of fungal biofilms to AMB and FLC demonstrated that the C. parapsilosis complex displayed an increased resistance to these antifungal agents. The results from these analyses may provide a basis for implementing quality controls and monitoring to ensure the microbiological purity of dialysis water, including the presence of yeast.

Treatment time, chronic inflammation, and hemodynamic stability: the overlooked parameters in hemodialysis quantification

Decades after the introduction of chronic maintenance hemodialysis, the optimal means of quantifying dialysis dose remains controversial. Differences of opinion in the international dialysis community lead to substantial diversity in everyday clinical practice. Several studies suggest that the well-recognized international mortality differences in hemodialysis populations may result from these divergent approaches to dialysis care. One of the main areas of divergence is the different degree of reliance on dialysis clearance when prescribing dialysis. The "clearance approach" implies that treatment quality is primarily dependent on efficient removal of uremic toxins as estimated by dialytic urea clearance. Urea can be rapidly removed by high efficiency dialysis in a relatively short time. The main alternative to this strategy is the "time approach" based on the recognition that longer or more frequent dialysis provides benefits beyond increasing urea removal. Some of the putative benefits are more effective volume and blood pressure control, better maintenance of hemodynamic stability because of slower ultrafiltration and removal of uremic toxins that do not behave like urea. Recently, chronic inflammation has been proposed to be an important predictor of outcome in dialysis patients. Inflammatory markers are commonly elevated in chronic renal failure and levels of these seem to correlate with malnutrition, maintenance of residual renal function, and volume control. The relationships between dialysis clearance, treatment time, chronic inflammation, volume control, and hemodynamic stability are explored in this review. We propose that a better understanding of these complex relationships may provide opportunities for improving outcomes of maintenance hemodialysis patients.

Bacterial DNA and endothelial damage in haemodialysis patients

BACKGROUND

An increased percentage of CD14+CD16+ activated monocytes have been reported in peripheral blood from haemodialysis patients. The aim of this study is to investigate if a mild stimulus such as bacterial DNA (CpG-ODNs) contamination may induce an inflammatory response in CD14+CD16+ monocytes from haemodialysis patients and to value the biological consequences of this inflammatory response on endothelial cell damage.

METHODS

Circulating mononuclear cells from 20 haemodialysis patients and 15 healthy subjects were studied. CD14+CD16+ and the toll-like receptor 9 (TLR-9) expression were assessed by flow cytometry. Cell culture inserts were used to evaluate the effect of CD14+CD16+ and CpG-ODNs on endothelial cell apoptosis (measured by Tunnel). Intracellular cytokines were measured by Cytometric methods. NF-kappaB, p38 MAPK, c-Jun PI3K and MEK1/2 activity were modified by specific peptides.

RESULTS

At baseline, CD14+CD16+ have an increased expression of cytoquines and TLR-9. CpG-ODNs caused the production and release of cytoquines in CD14+CD16+, but not in CD14++ monocytes. This inflammatory response was mediated by intracellular signalling dependent on NF-kappaB, p38 MARK or c-Jun PI3K but not by MEK1/2 activation. The results of the present study also demonstrate that the inflammatory response induced by the stimulation of CD14+CD16+ by CpG DNA resulted in endothelial cell apoptosis.

CONCLUSIONS

The results of the present study demonstrate that in haemodialysis patients there is a subpopulation of pre-activated monocytes that can be stimulated by contaminant bacterial DNA. These activated cells produce and release inflammatory factors that may cause endothelial injury.

Should renal nurses be aware of water quality?

Although traditionally considered the domain of the renal technologist, many units do not have technicians or may only have part-time access to one. In these cases, it often falls to nursing staff to ensure that patients are dialysed safely. However, water quality is an area in which some nurses do not feel confident. This paper is aimed at providing information about the importance of appropriate water treatment, water testing and monitoring and the implications to the patient if the water is not checked appropriately in accordance with the guidelines.

Impact of water quality and dialysis fluid composition on dialysis practice

An essential but frequently neglected aspect of dialysis treatment is the dialysis fluid produced by blending treated tap water with concentrated solutions containing electrolytes and buffer. Chemical and microbiological contaminants as well as the electrolyte and buffer composition of the dialysis fluid play major roles in the induction or modulation of morbidity associated with regular dialysis therapy.

Hepcidin in Anemia and Inflammation in Chronic Kidney Disease

Maintaining the correct iron balance is crucial for health. Our understanding of the molecular control of iron metabolism has increased dramatically over the past 5 years due to the discovery of hepcidin. This is a circulating antimicrobial peptide mainly synthesized in the liver, which has been recently proposed as a factor regulating the uptake of dietary iron and its mobilization from macrophages and hepatic stores. Inflammation causes an increase of production of hepcidin, which is a potent mediator of anemia of chronic diseases. Anemia in chronic kidney disease is mainly due to erythropoietin deficiency but these patients often have a chronic inflammatory state. The aim of this review is to summarize the current knowledge dealing with a possible role of hepcidin in iron metabolism and its regulation, particularly in kidney disease. In addition, current methods of determination of hepcidin are reviewed.

Inflammation in end-stage renal disease: the hidden enemy

Cardiovascular disease (CVD) remains the major cause of morbidity and mortality in end-stage renal disease (ESRD) patients. As traditional risk factors cannot alone explain the unacceptable high prevalence and incidence of CVD in this high-risk population, inflammation (interrelated to insulin resistance, oxidative stress, wasting and endothelial dysfunction) has been suggested to be a significant contributor. Indeed, several different inflammatory biomarkers, such as high sensitivity C-reactive protein (hs-CRP), have been shown to independently predict mortality in ESRD patients. As CRP is so strongly associated with vascular disease it has been suggested that this hepatic-derived protein is not only a marker, but also a mediator, of vascular disease. Although in vitro data from studies on endothelial cells, monocytes-macrophages and smooth muscle cells support a direct role for CRP in atherogenesis, data from studies performed in vivo have been controversial. The causes of the highly prevalent state of inflammation in ESRD are multiple, including inflammatory signals associated with the dialysis procedure, decreased renal function, volume overload, comorbidity and intercurrent clinical events. As the prevalence of inflammation varies considerably between continents and races, dietary and/or genetic factors may have an impact on inflammation in ESRD. Elevated CRP in dialysis patients could be evaluated at three different levels: (i) national/regional level; (ii) dialysis unit level; and (iii) individual patient level.

Biofilm: its relevance in kidney disease

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.

New insights on inflammation in chronic kidney disease–genetic and non-genetic factors

Cardiovascular disease (CVD) remains the major cause of morbidity and mortality in chronic kidney disease (CKD). As traditional risk factors cannot alone explain the unacceptable high prevalence and incidence of CVD in this population, inflammation (which is interrelated to insulin resistance, oxidative stress, wasting and endothelial dysfunction) has been suggested to be a significant contributor. Indeed, several different inflammatory biomarkers, such as high sensitivity C-reactive protein (CRP) has been shown to independently predict mortality in CKD patients. The causes of the highly prevalent state of inflammation in CKD are multiple and include factors such as volume overload, co-morbidity, intercurrent clinical events, the dialysis procedure per se as well as genetic factors. Indeed, multiple cytokine DNA polymorphisms may affect the inflammatory state, the clinical phenotype as well as outcome in this patient population.

The kind of vascular access influences the baseline inflammatory status and epoetin response in chronic hemodialysis patients

BACKGROUND

Arteriovenous grafts (AVG) and tunneled permanent catheters (TPC) are increasingly being used in hemodialysis (HD) patients. However, their role in baseline inflammatory status has not been fully evaluated. Aim of the study was to evaluate the influence of the current kind of vascular access on the baseline inflammatory status, marked by serum C-reactive protein (CRP), and the response to epoetin therapy in a group of iron-replete HD patients, under steady clinical conditions, without evidence of acute infections and/or inflammatory diseases.

METHODS

We studied 79 patients who had been on bicarbonate HD for 8-410 months and were receiving epoetin therapy. They all had adequate iron stores and stable hemoglobin (Hb) levels. Exclusion criteria were fever, signs of infection, white blood cell count (WBC) > 10 x 1,000/microl, for at least 4 weeks before study. 48 patients (group A) had arteriovenous fistula (AVF), 18 patients (group B) AVG, 13 patients (group C) TPC. CRP, Hb, transferrin saturation, serum ferritin, WBC, serum albumin, protein catabolic rate, Kt/V, and epoetin dose (U/kg body weight/week) were measured. CRP values were log-transformed to normalize the distribution.

RESULTS

Log-transformed CRP values among the 3 groups were significantly different: group A 1.81 +/- 0.48; group B 2.12 +/- 0.50, and group C 3.00 +/- 0.25 (group A vs. B p < 0.003; group B vs. C p < 0.001; group A vs. C p < 0.0001). CRP and the epoetin dose were directly correlated (r = 0.519; p < 0.0001). The epoetin doses among the 3 groups were significantly different. Multiple regression analysis confirmed AVG and TPC as factors independently influencing CRP levels.

CONCLUSIONS

AVG and TPC have a higher degree of chronic inflammation than AVF. The epoetin requirement is increased in TPC and AVG compared with AVF.

Water treatment and monitor disinfection

Water treatment system and dialysis monitors are susceptible to microbial contaminations and periodical disinfection procedures are mandatory to obtain results requested from international standards and guidelines. Several chemical germicides or some physical treatments are on the market validated by device manufacturer according to medical device directives. With time, interfering substances from dialysis device or water are able to modify disinfection efficiency. Simulating-use testing is not a common procedure to validate disinfectants and recent data document as biofilm represents the most important cause of disinfection inefficacy. Some international standards include tests in the presence of various interfering substances but their use is not widespread. When using a disinfectant, residue toxicity, material compatibility and potential risks for the staff also have to be considered. A quality assurance program has to be implemented to obtain adequate performances and to improve results on patients.

Dialysis Patients and Cardiovascular Problems: Can Technology Help Solve the Complex Equation?

Patients with end-stage kidney disease undergoing chronic hemodialysis (HD) present higher mortality rates compared with the general population. Once patients are on HD, the risk of cardiovascular death is approximately 30 times higher than in the general population and remains 10-20 times higher after stratification for age, gender, and the presence of diabetes. About half the deaths of patients on dialysis are attributed to cardiovascular causes including coronary heart disease, cerebrovascular disease, peripheral vascular disease, and heart failure. The cardiovascular burden of the HD patient arises from three different sources: risks inherent to the patient and the uremic syndrome, traditional risk factors, and risk factors related to the dialysis therapy. Based on these considerations and the fact that several aspects of the dialysis procedure can either add to the cardiovascular burden or modify the existing burden, new technologies should be directed towards the approach of a potential 'cardioprotective dialysis therapy'; such an approach may be facilitated by the application of new techniques and advanced dialysis machines. Created to make dialysis easy and safe, new machines feature several options that make patient monitoring and online hemodiafiltration therapy routine procedures. These and other features will possibly make dialysis better tolerated and more efficient in protecting patients from undesirable or potentially fatal cardiovascular events.