Peritoneal dialysis. Prevention and control of infection

Microbiological aspects of peritonitis in patients on continuous ambulatory peritoneal dialysis

The objective of the study was to identify the microbiological spectrum and drug-sensitivity pattern of peritonitis in patients on continuous ambulatory peritoneal dialysis. This was a prospective study done over a period of a year-and-a-half at a tertiary-care hospital in a hilly state of India. The effluent dialysate bags from 36 consecutive patients with peritonitis were studied. One hunderd ml dialysate fluid was processed under aseptic conditions by lysis centrifugation method. Microscopy and culture was done from the deposits for bacteriological, fungal, and mycobacterial isolates. They were identified by colony morphology and their biochemical reactions. Drug susceptibility testing was done by Kirby-Bauer disc diffusion method. In 36 dialysates, 33 (91.6%) dialysates were culture-positive and in 3 (8.4%), the culture was negative. A total of 36 microorganisms were isolated in 33 cultures. Among the 36 microorganisms, 19 (52.8%) isolates were gram-positive, 10 (27.8%) were gram-negative, 5 (13.9%) were fungi, and 2 (5.6%) were mycobacterial isolates. All gram-positive organisms were sensitive to ampicillin, amoxi-clavulanic acid, cefazolin, clindamycin, and vancomycin. Neither a methicillin-resistant Staphylococci aureus nor a vancomycin-resistant Enterococcus was isolated in gram-positive isolates. Gram-negative organisms were sensitive to ciprofloxacin, ceftriaxone, ceftazidime, cefepime, gentamicin, piperacillin–tazobactam and imipenem. One of the gram-negative isolate was an extended spectrum beta-lactamase producer. Gram-positive peritonitis was more frequent than gram-negative peritonitis in our continuous ambulatory peritoneal dialysis patients. Mycobacterial causes were responsible for peritonitis in patients with culture-negative peritonitis which was not responding to the conventional antimicrobial therapy.

Peritoneal dialysis fluid bioincompatibility and new vessel formation promote leukocyte-endothelium interactions in a chronic rat model for peritoneal dialysis

Peritoneal dialysis (PD)-induced peritonitis leads to dysfunction of the peritoneal membrane. During peritonitis, neutrophils are recruited to the inflammation site by rolling along the endothelium, adhesion, and transmigration through vessel walls. In a rat PD-model, long-term effects of PD-fluids (PDF) on leukocyte-endothelium interactions and neutrophil migration were studied under baseline and inflammatory conditions. Rats received daily conventional-lactate-buffered PDF (Dianeal), bicarbonate/lactate-buffered PDF (Physioneal) or bicarbonate/lactate buffer (Buffer) during five weeks. Untreated rats served as control. Baseline leukocyte rolling and N-formylmethionyl-leucyl-phenylalanine (fMLP) induced levels of transmigration in the mesentery were evaluated and quantified by intra-vital videomicroscopy and immunohistochemistry. Baseline leukocyte rolling was unaffected by buffer treatment, approximately 2-fold increased after Physioneal and 4-7-fold after Dianeal treatment. After starting fMLP superfusion, transmigrated leukocytes appeared outside the venules firstly after Dianeal treatment (15 minutes), thereafter in Physioneal and Buffer groups (20-22 minutes), and finally in control rats (>25 minutes). Newly formed vessels and total number of transmigrated neutrophils were highest in Dianeal-treated animals, followed by Physioneal and Buffer, and lowest in control rats and correlated for all groups to baseline leukocyte rolling (r = 0.78, P < 0.003). This study indicates that the start of inflammatory neutrophil transmigration is related to PDF bio(in)compatibility, whereas over time neutrophil transmigration is determined by the degree of neo-angiogenesis.

Angiotensin II upregulates Toll-like receptor 4 and enhances lipopolysaccharide-induced CD40 expression in rat peritoneal mesothelial cells

OBJECTIVE

Activation of Toll-like receptor 4 (TLR4) in peritoneal mesothelial cells by endotoxin contributes to peritoneal inflammation and fibrosis. Here we investigated TLR4 expression induced by angiotensin II (Ang II) and functional consequences of nuclear factor-kappaB (NF-kappaB) activation and CD40 expression in rat peritoneal mesothelial cells (RPMCs).

METHODS

TLR4, CD40, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) were determined by reverse transcription polymerase chain reaction (RT-PCR) and TLR4, IkappaBalpha, phospho-IkappaBalpha, NF-kappaB p65, and phospho-NF-kappaB p65 were analyzed by Western blot. The intracellular distribution of NF-kappaB p65 was detected by immunofluorescence.

RESULTS

Treatment of RPMCs with Ang II resulted in an increase in the expression of TLR4 mRNA and protein levels. Preincubation of RPMCs with Ang II significantly increased lipopolysaccharide (LPS)-induced phospho-IkappaBalpha and phospho-NF-kappaB p65 protein (P < 0.05 vs. LPS alone) and CD40, TNF-alpha, and IL-6 mRNA levels (P < 0.05 vs. LPS alone). A significantly increased nuclear staining of NF-kappaB p65 in cells treated with Ang II plus LPS was also observed.

CONCLUSIONS

Ang II upregulates the expression of TLR4 by RPMCs, resulting in enhanced NF-kappaB signaling and induction of CD40, TNF-alpha, and IL-6 expression. Locally produced Ang II in the peritoneum may have an amplified role in LPS-induced peritoneal inflammation.

Risk factors for peritoneal dialysis-related peritonitis: Can we reduce the incidence and improve patient selection?

BACKGROUND

Peritonitis is a serious complication of peritoneal dialysis (PD) and a major cause of hospitalization, catheter loss, transfer to haemodialysis and death. Thus, it is important to identify risk factors for PD-related peritonitis in order to reduce the incidence and improve patient selection.

METHODS

This study is a prospective cohort review (1992-2003) with data consisting of 12,844 patient months, 506 PD patients and 623 episodes of peritonitis. Comorbidities and patient demographics were provided by the Australian and New Zealand Dialysis and Transplant Registry and these were merged with the hospital combined clinical and microbiology laboratory peritonitis database.

RESULTS

Variables identified to be associated with an increased likelihood of peritonitis were: age (every 10 years; OR, 1.26; 95% CI, 1.07-1.48), gender (female; OR, 1.91; 95% CI, 1.2-3.01), current smoker at entry to dialysis (OR, 1.71; 95% CI, 1.04-2.82) and the pre twin bag connection system (OR, 2.07; 95% CI, 1.22-3.52).

CONCLUSION

Increasing age, female gender and smoking increased the risk of peritonitis. Identifying these risk factors will assist in the selection, training and monitoring of our PD population.

Icodextrin: a review of its use in peritoneal dialysis

Icodextrin (Extraneal) is a high molecular weight glucose polymer developed specifically for use as an alternative osmotic agent to dextrose during the once-daily long-dwell exchange in peritoneal dialysis (PD). Isosmotic 7.5% icodextrin solution induces transcapillary ultrafiltration (UF) by a mechanism resembling 'colloid' osmosis (unlike hyper-osmolar dextrose-based solutions, which induce UF by crystalline osmosis). In addition, absorption of icodextrin from the peritoneal cavity is relatively slow compared with that of dextrose; this results not only in UF of longer duration, but also a lower carbohydrate load compared with medium (2.5%) and strong (4.25%) dextrose exchanges. In randomised clinical trials of up to 2 years in duration, administration of icodextrin for the long (8- to 16-hour) overnight exchange in continuous ambulatory peritoneal dialysis (CAPD) or daytime exchange in automated peritoneal dialysis (APD) produced net UF which exceeded that with 1.5% and 2.5% dextrose solutions (thereby improving fluid balance), and was equivalent to that with 4.25% dextrose solution. Icodextrin also increased peritoneal clearances of creatinine and urea nitrogen compared with 2.5% dextrose solution. The increase in UF volume with icodextrin was enhanced in CAPD patients with high peritoneal membrane permeability (i.e. high and high-average transporters), maintained in the small number of patients followed-up for 2 years and sustained during episodes of peritonitis. Icodextrin reduced the percentage of patients with net negative UF in contrast to 1.5% and 2.5% dextrose and, in noncomparative studies, extended PD technique survival in patients who had failed dextrose-based dialysis. The use of icodextrin was also associated with some symptomatic improvements and health-related quality of life advantages, and no adverse effect on patient survival, compared with dextrose, although confirmation of these findings is ideally required in appropriately designed studies. The tolerability of icodextrin was generally similar to that of dextrose-based solutions in controlled clinical trials, although there was an approximate three-fold increase in the risk of new skin rash (5.5% vs 1.7%). However, reports of severe cutaneous hypersensitivity reactions remain rare; this possibility should not preclude the use of the polymer.

CONCLUSION

7.5% icodextrin solution offers the first feasible alternative to conventional dextrose solutions for the once-daily long-dwell exchange in PD. It is effective, generally well tolerated and appears to be most useful in situations of reduced or inadequate UF with dextrose, including in high and high-average transporters, during episodes of peritonitis and patients who have failed dextrose-based dialysis.

Effects of conventional and new peritoneal dialysis fluids on leukocyte recruitment in the rat peritoneal membrane

Peritonitis remains an important cause of morbidity and technique failure in peritoneal dialysis (PD). Conventional peritoneal dialysate fluids (PDF) inhibit peritoneal leukocyte function in vitro and may thus adversely affect the immune response to peritonitis. New PDF have been designed with neutral pH, low glucose degradation product (GDP) contents, and bicarbonate as buffer. The present intravital microscopy study examined the effects of conventional and new PDF on leukocyte behavior in the peritoneal microcirculation of Wistar rats. The visceral peritoneum was superfused by a control solution (EBSS), a conventional (CAPD), or a new bicarbonate-buffered PDF with neutral pH and low GDP content (CAPD BicaVera). In addition, spent conventional and new PDF were tested. The number of rolling, adhering, and extravasated leukocytes and leukocyte rolling velocity were assessed at different time intervals after exposure to lipopolysaccharide (LPS) or cell-free supernatants of coagulase-negative staphylococci (CNS-CFS). Exposure to LPS or CNS-CFS dissolved in EBSS dramatically increased the number of rolling, adhering and extravasated leukocytes and decreased leukocyte rolling velocity. Superfusion by CAPD abolished the LPS- or CNS-CFS-induced leukocyte recruitment, whereas CAPD BicaVera had significantly fewer depressant effect. Spent PDF affected the leukocyte response in a similar way as fresh PDF. High lactate concentrations, GDP, and hypertonicity appeared to be mainly responsible for the inhibition of leukocyte recruitment. In conclusion, conventional PDF abolish in vivo leukocyte recruitment in response to potent inflammatory stimuli. Bicarbonate-buffered pH-neutral PDF with low GDP contents have fewer depressant effects and may therefore contribute to a better preservation of peritoneal host defense.

Comparison of clinical outcome and ease of handling in two double-bag systems in continuous ambulatory peritoneal dialysis: a prospective, randomized, controlled, multicenter study

BACKGROUND

We performed a prospective, randomized, controlled, multicenter study on the use of two double-bag disconnect systems: Stay-Safe (SS; Fresenius Deutschland GmbH2) and Ultrabag (UB; Baxter Healthcare, Deerfield, IL) to assess the ease of handling, peritonitis rate, exit-site infection rate, and clinical outcome.

METHODS

We enrolled 110 new continuous ambulatory peritoneal dialysis (CAPD) patients; 55 patients were randomized to SS treatment, and 55 patients, to UB treatment.

RESULTS

Patients using the UB and SS systems were followed up for 946 and 846 patient-months, respectively. There were 21 episodes of peritonitis in 18 patients in the UB group and 23 episodes in 18 patients in the SS group. No significant difference was observed in peritonitis rates between the two systems, which were 45 and 36.8 patient-months per episode for the UB and SS groups, respectively. At 12 months, 82.1% of patients in the UB group and 72.1% in the SS group were free of peritonitis; at 18 months, 71.1% and 62.2% were free of peritonitis for the UB and SS groups, respectively (P = 0.559). Gram-positive organisms accounted for 28.6% of infections in the UB group and 39.1% in the SS group. Exit-site infection rates were one episode per 21 patient-months versus 19.2 patient-months in the UB and SS groups, respectively (P = 0.743). Patients perceived SS as easier to handle in 4 of the 13 steps immediately post-CAPD training. However, there was no significant difference in rankings between the two systems after 1 month of adaptation. Median training periods were 4 and 5 days for the SS and UB groups, respectively (P = 0.640).

CONCLUSION

The two double-bag systems (UB and SS) have similar incidences of peritonitis and exit-site infection. Both systems showed comparably good clinical outcome. The SS system is easier to learn during the initial training period, but the difference is not significant after 1 month's adaptation.

Renal function and renal disease in the elderly: Part II

In all industrialized countries, life expectancy has risen in the past 100 years. The incidence of elderly patients reaching end-stage renal disease (ESRD) and requiring renal replacement therapy has also increased. During the past few decades, the pattern of ESRD has changed significantly with the emerging predominance of elderly patients. The causes of this phenomenon are manifold and include an increasing number of chronic diseases typical of the 'third age', such as type 2 diabetes mellitus and vascular disease. In many species, a consequence of aging includes deterioration of renal function, partly due to structural alterations, and partly as the result of a diminishing blood flow. In humans, the aging kidney is characterized by modifications resulting from organic and functional disturbances. In particular, type 2 diabetes mellitus has emerged as an important condition, the microvascular and macrovascular complications of which are a common cause of morbidity and mortality in older patients. In Part II of this review, the specific aspects of renal replacement therapy in the elderly will be discussed.