[Ecology and mechanisms of bacterial resistance to antibiotics in peritonitis]

Peritonitis remains a common complication of peritoneal dialysis. The aim of our study is to describe the mechanisms of antibiotic resistance in bacteria isolated during peritonitis in peritoneal dialysis, to determine whether antibiotic therapy proposed by the International Society for Peritoneal Dialysis (ISPD) is adapted to the mechanisms of resistance. All causative microorganisms of peritonitis, isolated in 106 dialysis patients and reported 170 episodes of peritonitis, during the study period (01/01/2005 to 31/12/2010) were reviewed. According to the usual classification, twelve groups of microorganism were created. An interpretive reading of antibiograms was performed in each group to identify resistance phenotypes. The species most frequently isolated are coagulase-negative staphylococci (n=73) of which 46 had PBP2a (penicillin-binding protein). Many Enterobacteriaceae were also isolated (n=45), they are susceptible to third generation cephalosporins with the exception of Enterobacteriaceae producing an extended spectrum β-lactamase (ESBL) or a cephalosporinase. Except for staphylococci, probabilistic antibiotic therapy recommended by the ISPD to treat peritonitis is effective. Indeed, many staphylococci producing a PBP2a, a first-generation cephalosporin cannot be administered in all cases. It is therefore necessary to identify patients with a strain of staphylococcus producing a PBP2a, it must be treated by vancomycin.

Peritoneal dialysis-associated peritonitis rates and outcomes in a national cohort are not improving in the post-millennium (2000-2007)

BACKGROUND

Peritoneal dialysis (PD)-related peritonitis remains the leading cause of technique failure and a significant cause of morbidity among PD patients. Rates in the literature vary, reflecting differences in study design and in populations. The objective of the present study was to determine peritonitis incidence and outcomes in Scotland and to compare them with national guidelines.

METHODS

All 10 adult renal units in Scotland prospectively collect data relating to peritonitis for all PD patients in Scotland. Complete audit data between 1 January 2000 and 31 December 2007 were analyzed for the study.

RESULTS

The 1918 peritonitis episodes in 38 106 PD treatment months yielded a national rate of 1 episode every 19.9 months. The UK Renal Association standard was met every year, but is not consistently improving. The median peritonitis-free survival was 526 days (95% confidence interval: 463 to 589 days). The spectrum of causative organisms reflected those in previous reports, with a culture-negative rate of 19.4%. Nationally, the cure rate was 74.6%, the refractory rate was 22.6%, and the death rate was 2.8%. Outcome varied by organism. Recurrences represented 9.3% of episodes, and technique failure occurred in 14.9%. The peritonitis rate was higher for continuous ambulatory PD patients than for automated PD patients (1 episode every 17.6 months vs 1 episode every 22.3 months, p < 0.001, relative risk: 1.27). There were significant differences between renal units.

CONCLUSIONS

This large national PD cohort met targets for peritonitis rates every year during the 8 years covered by the present report, but showed no consistent trend for improvement. Peritonitis remains the main cause of technique failure in Scotland. Peritonitis rates varied widely between the units, which suggests that we should look to the units and countries with lower peritonitis rates to see if we can adopt successful elements of their practice before resigning ourselves to our ongoing peritonitis burden.

High rates of mortality and technique failure in peritoneal dialysis patients after critical illness

INTRODUCTION

Little is known regarding the causes and outcomes of peritoneal dialysis (PD) patients admitted to the intensive care unit (ICU). We explored the outcomes of technique failure and mortality in a cohort of PD patients admitted to the ICU.

METHODS

Using a provincial database of 990 incident PD patients followed from January 1997 to June 2009, we identified 90 (9%) who were admitted to the ICU. Parametric and nonparametric tests were used as appropriate to determine differences in baseline characteristics. The Cox proportional hazards and competing risk methods were used to investigate associations.

RESULTS

Compared with other patients, those admitted to the ICU had been on PD longer (p < 0.0001) and were more often on continuous ambulatory PD (74.2% vs 25.8%, p = 0.016). Cardiac problems were the most common admitting diagnosis (50%), followed by sepsis (23%), with peritonitis accounting for 69% of the sepsis admissions. The 1-year mortality was 53.3%, with 12% alive and converted to hemodialysis, and one third remaining alive on PD. In multivariate Cox modeling, age [hazard ratio (HR): 1.01; 95% confidence interval (CI): 0.99 to 1.03], white blood cell count (HR: 1.02; 95% CI: 1.00 to 1.04), temperature (HR: 0.75; 95% CI: 0.61 to 0.92), and peritonitis (1.64; 95% CI: 1.21 to 2.22) at admission to the ICU were associated with the composite outcome of technique failure or death. In a competing risk analysis, the risk for death was 30%, and for technique failure, 36% at 1 year.

CONCLUSIONS

Patients on PD have high rates of death and technique failure after admission to the ICU.

Human neutrophil clearance of bacterial pathogens triggers anti-microbial γδ T cell responses in early infection

Human blood Vγ9/Vδ2 T cells, monocytes and neutrophils share a responsiveness toward inflammatory chemokines and are rapidly recruited to sites of infection. Studying their interaction in vitro and relating these findings to in vivo observations in patients may therefore provide crucial insight into inflammatory events. Our present data demonstrate that Vγ9/Vδ2 T cells provide potent survival signals resulting in neutrophil activation and the release of the neutrophil chemoattractant CXCL8 (IL-8). In turn, Vγ9/Vδ2 T cells readily respond to neutrophils harboring phagocytosed bacteria, as evidenced by expression of CD69, interferon (IFN)-γ and tumor necrosis factor (TNF)-α. This response is dependent on the ability of these bacteria to produce the microbial metabolite (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP), requires cell-cell contact of Vγ9/Vδ2 T cells with accessory monocytes through lymphocyte function-associated antigen-1 (LFA-1), and results in a TNF-α dependent proliferation of Vγ9/Vδ2 T cells. The antibiotic fosmidomycin, which targets the HMB-PP biosynthesis pathway, not only has a direct antibacterial effect on most HMB-PP producing bacteria but also possesses rapid anti-inflammatory properties by inhibiting γδ T cell responses in vitro. Patients with acute peritoneal-dialysis (PD)-associated bacterial peritonitis – characterized by an excessive influx of neutrophils and monocytes into the peritoneal cavity – show a selective activation of local Vγ9/Vδ2 T cells by HMB-PP producing but not by HMB-PP deficient bacterial pathogens. The γδ T cell-driven perpetuation of inflammatory responses during acute peritonitis is associated with elevated peritoneal levels of γδ T cells and TNF-α and detrimental clinical outcomes in infections caused by HMB-PP positive microorganisms. Taken together, our findings indicate a direct link between invading pathogens, neutrophils, monocytes and microbe-responsive γδ T cells in early infection and suggest novel diagnostic and therapeutic approaches.

The immune system of all jawed vertebrates harbors three distinct lymphocyte populations – αβ T cells, γδ T cells and B cells – yet only higher primates including humans possess so-called Vγ9/Vδ2 T cells, an enigmatic γδ T cell subset that uniformly responds to the majority of bacterial pathogens. For reasons that are not understood, this responsiveness is absent in all other animals although they too are constantly exposed to a plethora of potentially harmful micro-organisms. We here investigated how Vγ9/Vδ2 T cells respond to live microbes by mimicking physiological conditions in acute disease. Our experiments demonstrate that Vγ9/Vδ2 T cells recognize a small common molecule released when invading bacteria become ingested and killed by other white blood cells. The stimulation of Vγ9/Vδ2 T cells at the site of infection amplifies the inflammatory response and has important consequences for pathogen clearance and the development of microbe-specific immunity. However, if triggered at the wrong time or the wrong place, this rapid reaction toward bacteria may also lead to inflammation-related damage. These findings improve our insight into the complex cellular interactions in early infection, identify novel biomarkers of diagnostic and predictive value and highlight new avenues for therapeutic intervention.

Identification of Coagulase-Negative Staphylococci Isolated from Continuous Ambulatory Peritoneal Dialysis Fluid using 16s Ribosomal RNA, tuf, and SodA Gene Sequencing

Introduction

Coagulase-negative staphylococcus (CoNS) is the most common pathogen in continuous ambulatory peritoneal dialysis (CAPD)–associated peritonitis. There is no well-organized, standardized database for CoNS, and few studies have used gene sequencing in reporting species distribution in CAPD peritonitis. In the present study, we used 3 housekeeping genes to evaluate the prevalence of CoNS isolated from CAPD peritonitis episodes and to estimate the accuracy of, and the characteristic differences between, these genes for species identification.

Methods

All 51 non-duplicated CoNS isolates obtained from CAPD peritonitis between April 2006 and May 2008 were used. The strains were identified by polymerase chain reaction and by direct sequencing using the 16S ribosomal RNA (rRNA), tuf, and sodA genes. We determined species distribution, and using selected databases, we analyzed the characteristics and diagnostic utility of the individual genes for species identification.

Results

In GenBank (National Institutes of Health, Bethesda, MD, USA), we found 49 type or reference strains for CoNS 16S rRNA, 17 for tuf, and 46 for sodA, and we used those data for sequence-similarity comparisons with CAPD isolates. Among our 51 strains, S. epidermidis (66.7%) was the most common, followed by S. haemolyticus (11.8%), S. warneri (7.8%), S. caprae (5.9%), S. capitis (3.9%), and S. pasteuri (2.0%). For 1 strain, different species results were obtained with each gene. The identification rates with 16S rRNA, sodA, and tuf gene sequencing were 84.0%, 96.0%, and 92.2% respectively. The discrimination capability of 16S rRNA gene was lower in a few individual species, and for the sodA gene, the percentage similarity to sequences from reference strains was also lower. The tuf gene had excellent identification capacity, but relatively few type strains are available in public databases. The 16S rRNA gene did not discriminate between S. caprae and S. capitis. The sodA gene showed a similarity rate that was lower than that for sequences of the 16S rRNA gene. The tuf type strain sequences for S. caprae and S. pasteuri are not available in public databases.

Conclusions

The sodA, tuf, and 16S rRNA genes were very useful for CoNS identification. Each has its own characteristics of similarity, discriminative power, and inclusion in databases.

Comparative analysis of two-piece extended peritoneal dialysis catheters with remote exit-site locations and conventional abdominal catheters

BACKGROUND

An alternative peritoneal catheter exit-site location is sometimes needed in patients with obesity, floppy skin folds, intestinal stomas, urinary and fecal incontinence, and chronic yeast intertrigo. Two-piece extended catheters permit remote exit-site locations away from problematic abdominal conditions.

OBJECTIVE

The effect on clinical outcomes by remotely locating catheter exit sites to the upper abdomen or chest was compared to conventional lower abdominal sites.

METHODS

In a nonrandomized design, peritoneal access was established with 158 extended catheters and 270 conventional catheters based upon body habitus and special clinical needs. Prospective data collection included patient demographics, infectious and mechanical complications, and catheter survival.

RESULTS

Kaplan-Meier survival time until first exit-site infection was longer for extended catheters (p = 0.03). Poisson regression showed no difference in exit site, subcutaneous tunnel, and peritonitis infection rates; however, the proportion of catheters lost during peritonitis episodes was significantly greater for extended catheters (p = 0.007) and appeared to be due primarily to coagulase-negative staphylococcus organisms. Poisson regression showed interactions of body mass index (BMI) and diabetic status in determining catheter loss from peritonitis for both catheter types (p = 0.02). Extended catheter patients had higher BMI and diabetes prevalence (p < 0.0001). Overall extended catheter survival at 1, 2, and 3 years (92%, 80%, 71%) trended lower than conventional devices (93%, 87%, 80%; p = 0.0505).

CONCLUSIONS

Extended catheters enable peritoneal access for patients in whom conventional catheter placement would be difficult or impossible. Certain patient and extended-catheter characteristics may contribute to loss from peritonitis.

Positive dialysate gram stain predicts outcome of empirical antibiotic therapy for peritoneal dialysis-associated peritonitis

Empirical antibiotic treatment with a first-generation cephalosporin plus gentamicin for peritoneal dialysis (PD)-associated peritonitis before culture results are available is still wildly used due to concerns regarding the economic burden and antibiotic-resistant bacterial infections. The aim of this study is to define the factors that predict the outcome of empirical antibiotic therapy for PD peritonitis. This is a retrospective study of patients with PD peritonitis over the last 10 years. Patients who had been treated empirically with intermittent intraperitoneal first-generation cephalosporin and gentamicin were enrolled. Eighty-three patients had 192 episodes of PD peritonitis. In total, 159 peritonitis episodes were treated with intraperitoneal antibiotics combined with first-generation cephalosporin and gentamicin empirically. Twenty-five peritonitis episodes had no pathogens identified by dialysate culture. In total, 122 (122/159, 76.7%) PD peritonitis episodes were caused by bacteria, 9 (9/159, 5.7%) were fungal, and 3 (3/159, 1.9%) were Mycobacterium tuberculosis peritonitis. Sixty-four (64/159, 40.3%) peritonitis episodes were successfully cured by empirical intraperitoneal antibiotic therapy. Empirical antibiotic treatment failed in 95 episodes (95/159, 59.7%). The positive rates of dialysate Gram stain in the empirical treatment success and failure groups were 15.6% and 40.0%, respectively (P = 0.001). The odds ratio of empirical treatment failure with a positive bacteria Gram stain was 3.60 (95% CI: 1.65-7.82). The dialysate Gram staining result was a significant predictor of empirical antibiotics treatment outcome for PD-associated peritonitis. Therefore, using an empirical antibiotic regimen for patients with an initial positive bacterial Gram stain of the dialysate should be introduced cautiously.

Enterococcal peritonitis in children receiving chronic peritoneal dialysis

BACKGROUND

Peritonitis is a common complication of chronic peritoneal dialysis (CPD) and can be associated with technique failure. Enterococcus is an uncommon peritoneal pathogen in children receiving CPD but represents a potential therapeutic challenge due to its innate resistance to cephalosporins and emerging resistance to glycopeptides.

METHODS

The International Pediatric Peritonitis Registry is a global consortium of 47 paediatric dialysis centres designed to address validation of the International Society for Peritoneal Dialysis paediatric peritonitis treatment guidelines. Between 2001 and 2004, peritonitis episodes were assessed in 392 participating children receiving CPD.

RESULTS

Among the 392 patients, 340 episodes of culture-positive peritonitis were evaluated. Twenty of these episodes were due to Enterococcus species (5.9%). There were no clinical characteristics uniquely associated with enterococcal peritonitis at presentation. After 3 days of therapy, 75% of patients were pain free, 95% had decreased effluent cloudiness and 90% were afebrile. Only one patient required a catheter exchange, and all patients experienced full functional recovery. Despite broad in vitro resistance to cephalosporins and 21% resistance to glycopeptides, neither in vitro resistance pattern nor choice of empiric antibiotic regimen affected short- or long-term outcomes.

CONCLUSIONS

Enterococci are likely responsible for ∼6% of culture-positive peritonitis episodes in children receiving CPD. Although it was not possible to identify patients with enterococcal peritonitis based on presentation, clinical response was not associated with in vitro resistance patterns, and patients who initially received a cephalosporin-based empiric regimen until culture results are available are likely to respond quickly and have full functional recovery.

Coagulase-negative staphylococcal peritonitis in Australian peritoneal dialysis patients: predictors, treatment and outcomes in 936 cases

BACKGROUND

Coagulase-negative staphylococcal (CNS) peritonitis is the most common cause of peritoneal dialysis (PD)-associated peritonitis. Previous reports of this important condition have been sparse and generally limited to single-centre studies.

METHODS

The frequency, predictors, treatment and clinical outcomes of CNS peritonitis were examined by multivariate logistic regression and multilevel Poisson regression in all adult PD patients in Australia between 2003 and 2006.

RESULTS

A total of 936 episodes of CNS peritonitis (constituting 26% of all peritonitis episodes) occurred in 620 individuals. The observed rate of CNS peritonitis was 0.16 episodes per patient-year. Lower rates of CNS peritonitis were independently predicted by Asian racial origin (adjusted odds ratio [OR], 0.52; 95% CI, 0.35-0.79), renovascular nephrosclerosis (OR, 0.40; 95% CI, 0.18-0.86), early referral to a renal unit prior to dialysis commencement (OR, 0.38; 95% CI, 0.19-0.79) and treatment with automated PD at any time during the PD career (OR, 0.79; 95% CI, 0.66-0.96). The majority of CNS peritonitis episodes were initially treated with intraperitoneal vancomycin or cephazolin in combination with gentamicin. This regimen was changed in 533 (57%) individuals after a median period of 3 days, most commonly to vancomycin monotherapy. The median total antibiotic course duration was 14 days. Compared with other forms of peritonitis, CNS episodes were significantly more likely to be cured by antibiotics alone (76 vs 64%, P < 0.001) and less likely to be complicated by hospitalization (61 vs 73%, P < 0.001), catheter removal (10 vs 26%, P < 0.001), temporary haemodialysis (2 vs 5%, P < 0.001), permanent haemodialysis transfer (9 vs 21%, P < 0.001) and death (1.0 vs 2.7%, P = 0.002). CNS peritonitis was also associated with a shorter duration of hospitalization, a longer time to catheter removal and a shorter duration of temporary haemodialysis. Catheter removal and permanent haemodialysis transfer were independently predicted by polymicrobial peritonitis and initial empiric administration of vancomycin (compared with cephalosporins). CNS peritonitis was associated with a higher relapse rate (17 vs 13%, P = 0.003) and relapsed CNS peritonitis was associated with a higher catheter removal rate (22 vs 7%, P < 0.001). Repeat peritonitis occurred in 194 (31%) individuals and the highest risk was in the second month after completion of antibiotic treatment for CNS peritonitis (OR, 1.87; 95% CI, 1.39-2.51 compared with >2 months).

CONCLUSIONS

CNS peritonitis is a common complication with a relatively benign outcome compared with other forms of PD-associated peritonitis. Relapsed and repeat peritonitis are relatively common and are associated with worse outcomes.

Dialysis-associated peritonitis in children

Peritonitis remains a frequent complication of peritoneal dialysis in children and is the most common reason for technique failure. The microbiology is characterized by a predominance of Gram-positive organisms, with fungi responsible for less than 5% of episodes. Data collected by the International Pediatric Peritonitis Registry have revealed a worldwide variation in the bacterial etiology of peritonitis, as well as in the rate of culture-negative peritonitis. Risk factors for infection include young age, the absence of prophylactic antibiotics at catheter placement, spiking of dialysis bags, and the presence of a catheter exit-site or tunnel infection. Clinical symptoms at presentation are somewhat organism specific and can be objectively assessed with a Disease Severity Score. Whereas recommendations for empiric antibiotic therapy in children have been published by the International Society of Peritoneal Dialysis, epidemiologic data and antibiotic susceptibility data suggest that it may be desirable to take the patient- and center-specific history of microorganisms and their sensitivity patterns into account when prescribing initial therapy. The vast majority of patients are treated successfully and continue peritoneal dialysis, with the poorest outcome noted in patients with peritonitis secondary to Gram-negative organisms or fungi and in those with a relapsing infection.

The role of virulence factors in the outcome of staphylococcal peritonitis in CAPD patients

Background

Peritonitis continues to be the most frequent cause of peritoneal dialysis (PD) failure, with an important impact on patient mortality. Gram-positive cocci such as Staphylococcus epidermidis, other coagulase-negative staphylococci (CoNS), and Staphylococcus aureus are the most frequent etiological agents of PD-associated peritonitis worldwide. The objective of the present study was to compare peritonitis caused by S. aureus and CoNS and to evaluate the factors influencing outcome.

Methods

Records of 86 new episodes of staphylococcal peritonitis that occurred between 1996 and 2000 in the Dialysis unit of a single university hospital were studied (35 due to S. aureus, 24 to S. epidermidis and 27 to other CoNS). The production of slime, lipase, lecithinase, nuclease (DNAse), thermonuclease (TNAse), α- and β-hemolysin, enterotoxins (SEA, SEB, SEC, SED) and toxic shock syndrome toxin-1 (TSST-1) was studied in S. aureus and CoNS. Antimicrobial susceptibility was evaluated based on the minimal inhibitory concentration determined by the E-test. Outcome predictors were evaluated by two logistic regression models.

Results

The oxacillin susceptibility rate was 85.7% for S. aureus, 41.6% for S. epidermidis, and 51.8% for other CoNS (p = 0.001). Production of toxins and enzymes, except for enterotoxin A and α-hemolysin, was associated with S. aureus episodes (p < 0.001), whereas slime production was positive in 23.5% of CoNS and 8.6% of S. aureus strains (p = 0.0047). The first model did not include enzymes and toxins due to their association with S. aureus. The odds of resolution were 9.5 times higher for S. epidermidis than for S. aureus (p = 0.02) episodes, and were similar for S. epidermidis and other CoNS (p = 0.8). The resolution odds were 68 times higher for non-slime producers (p = 0.001) and were not influenced by oxacillin resistance among vancomycin-treated cases (p = 0.89). In the second model, the resolution rate was similar for S. aureus and S. epidermidis (p = 0.70), and slime (p = 0.001) and α-hemolysin (p = 0.04) production were independent predictors of non-resolution.

Conclusion

Bacterial species and virulence factors rather than antibiotic resistance influence the outcome of staphylococcal peritonitis.

Enterococcal peritonitis in Australian peritoneal dialysis patients: predictors, treatment and outcomes in 116 cases

Background. Enterococcal peritonitis is a serious complication of peritoneal dialysis (PD), although reports of this condition in the literature are exceedingly limited. Methods. The frequency, predictors, treatment and clinical outcomes of enterococcal peritonitis were investigated in all 4675 patients receiving PD in Australia between 1 October 2003 and 31 December 2006. Results. One hundred and sixteen episodes of enterococcal peritonitis occurred in 103 individuals. Enterococcal peritonitis tended to be associated with older age, Maori and Pacific Islander racial origin, renovascular disease and coronary artery disease. Polymicrobial peritonitis, defined as recovery of two or more organisms from dialysate effluent, was significantly more common when an Enterococcus species was isolated than when it was not (45% vs 5%, respectively, P < 0.001, odds ratio 13.4, 95% CI 9.45-19.0). Although international guidelines recommend intraperitoneal ampicillin therapy, only 8% of patients with pure enterococcal peritonitis were treated with this agent, whilst the majority (78%) received vancomycin monotherapy. Overall, 59 (51%) patients with enterococcal peritonitis were successfully treated with antibiotics without experiencing relapse, catheter removal or death. The sole independent predictor of adverse clinical outcomes was recovery of additional (non-Enterococcus) organisms. Polymicrobial enterococcal peritonitis was associated with very high rates of hospitalization (83%), catheter removal (52%), permanent haemodialysis transfer (50%) and death (5.8%). In contrast, clinical outcomes were broadly comparable for pure enterococcal and non-enterococcal peritonitis (hospitalization 75% vs 69%, respectively; catheter removal 25% vs 21%; permanent haemodialysis transfer 17% vs 17%; death 1.6% vs 2.2%) although worse than non-enterococcal Gram-positive peritonitis (63%, 12%, 3% and 0.6%, respectively). Removal of the PD catheter within 1 week of enterococcal peritonitis onset was associated with a lower probability of permanent haemodialysis transfer than later removal (74% vs 100%, P = 0.03).

CONCLUSIONS

Enterococcal peritonitis is associated with an increased risk of catheter removal, permanent haemodialysis transfer and death, particularly when other organisms are isolated in the same episode.

Peritonitis Remains the Major Clinical Complication of Peritoneal Dialysis: The London, Uk, Peritonitis Audit 2002–2003

Background

Over the past two decades, the rate of peritonitis in patients treated by peritoneal dialysis (PD) has been significantly reduced. However, peritonitis remains a major complication of PD, accounting for considerable mortality and hospitalization among PD patients.

Objective

To compare the outcome of peritonitis in a large unselected group of PD patients with that from singlecenter and selected groups.

Method

We audited the outcome of peritonitis in PD patients attending the 12 PD units in the Thames area in 2002 and 2003. There were 538 patients on continuous ambulatory PD (CAPD) and 325 patients on automated PD (APD) and/or continuous cycling PD (CCPD) at the end of 2002, and 635 CAPD and 445 APD/CCPD patients at the end of 2003.

Results

There were 1467 episodes of PD peritonitis during the 2-year period, including 129 recurrent episodes, with the average number of months between peritonitis episodes being 14.7 for CAPD and 18.1 for APD/CCPD, p < 0.05. However there was considerable variation between units. Coagulase-negative staphylococcus (CoNS) was the most common cause, accounting for around 30% of all peritonitis episodes, including recurrences, followed by non-pseudomonas gram negatives and Staphylococcus aureus. Cure rates were 77.2% for CoNS, 46.6% for S. aureus, and 7.7% for methicillin-resistant S. aureus. The cure rate for pseudomonas was 21.4%, and other gram negatives 56.7%. In total, there were 351 episodes of culture-negative peritonitis, with an average cure rate of 76.9%. Cure rates were higher for those centers that used a combination of intraperitoneal gentamicin and cephalosporins than those centers that used oral-based regimes. A total of 296 PD catheters were removed as a direct consequence of PD peritonitis: 121 due to gram-positive and 123 due to gram-negative organisms. Only 49 catheters were reinserted and the patients returned to PD. 52 patients died during or subsequent to their episode of PD peritonitis, with an overall mortality rate of 3.5%.

Conclusion

This audit showed that, in a large unselected population of PD patients, the incidence of peritonitis was significantly greater than that reported in single-center short-term studies, and varied from unit to unit. Similarly, the success of treating PD peritonitis varied not only with the cause of the infection but also from unit to unit. PD peritonitis remains a major cause of patients discontinuing PD and switching to hemodialysis.

Impact of age on peritonitis risk in peritoneal dialysis patients: an era effect

BACKGROUND AND OBJECTIVES

Despite reductions in the frequency of peritoneal dialysis (PD)-related infectious complications over time, peritonitis and catheter infection remain important causes of morbidity and mortality. Given the increasing number of elderly patients reaching end-stage renal disease, making informed decisions about PD utilization is contingent on an understanding of the infectious complications of PD in this population. We therefore studied the impact of age on infection rates, organisms and outcomes.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

On the basis of data collected from 1996 to 2005 in the multicenter Baxter Peritonitis Organism Exit sites Tunnel infections database, the study population included 4247 incident Canadian PD patients: 1265 patients aged > or =70 yr and 2982 patients aged <70 yr. We defined two eras of PD initiation: 1996 to 2000 and 2001 to 2005.

RESULTS

In a negative binomial model, older age was independently associated with a higher peritonitis rate (rate ratio [RR] 1.06 per decade increase; 95% CI 1.01 to 1.10; P = 0.008). However, this association was present only among those who initiated PD at an earlier time (RR 1.13 per decade increase; 95% CI 1.07 to 1.20; P < 0.001 in 1996 to 2000 versus 1.01 per decade increase; 95% CI 0.95 to 1.06; P = 0.81 in 2001 to 2005). Catheter-related infections were less frequent with increasing age regardless of era (RR 0.93 per decade increase; 95% CI 0.89 to 0.97).

CONCLUSIONS

The higher peritonitis rate observed in elderly patients may represent an era effect, as age was not associated with peritonitis among patients initiating PD between 2001 and 2005. In addition, catheter infection was less frequent with increasing age.

Surgical Peritonitis in Patients on Peritoneal Dialysis

In this short review we highlight the diagnostic challenge presented by surgical peritonitis in peritoneal dialysis patients, giving attention to etiology, clinical presentation, diagnosis, and management. Despite improvements in medical imaging and a reduction in overall rates of peritonitis in peritoneal dialysis, the mortality of surgical peritonitis has not changed in recent years and remains a challenge for the clinical team.

Gram-negative peritonitis in children undergoing long-term peritoneal dialysis

BACKGROUND

The proportion of gram-negative causative organisms in peritoneal dialysis-associated peritonitis is increasing. Little published information for this complication exists in children. The objective of this study is to evaluate the clinical presentation, early and late response to treatment, and identification of factors influencing the outcome of gram-negative peritonitis (GNP) in children.

STUDY DESIGN

Case series.

SETTING AND PARTICIPANTS

104 children (aged 7.9 +/- 5.9 years) with 121 GNP episodes reported to the International Pediatric Peritonitis Registry from October 2001 through December 2004.

PREDICTORS

Patient, clinical, bacteriological, and treatment features.

OUTCOMES

Initial response to empirical treatment was assessed after approximately 72 hours of therapy. Final outcome was judged according to the occurrence of death, technique failure, relapse, need for catheter exchange, and a composite end point defining full functional recovery.

RESULTS

44% of episodes of GNP occurred in children younger than 5 years. Causative organisms included Pseudomonas species, 21%; Klebsiella species, 18%; Escherichia coli, 17%; and Acinetobacter species, 12%. Thirty-two percent of organisms classified as gram-negative were not identified further. Clinical manifestations were severe and uniform for all causative gram-negative agents. A substantial proportion (20%) of organisms were resistant to ceftazidime, with resulting suboptimal response to empirical therapy. By day 3 of initial empiric treatment, 85% of children with GNP had improved clinically (39%, complete resolution; 46%, improvement in symptoms), 10% showed poor response, and 5% had worsening of symptoms. Multivariate analysis identified severe abdominal pain, use of a single-cuff catheter, and intermittent (versus continuous) intraperitoneal ceftazidime administration as independent predictors of worse initial response to treatment. Full functional recovery was achieved in 86% of episodes. Nineteen patients (16%) required catheter removal, 11 (9%) experienced a relapse, 7 (6%) discontinued peritoneal dialysis therapy permanently, and 3 died. Lack of clinical improvement after 72 hours of therapy (odds ratio, 5.39; P < 0.01) and the presence of an exit-site infection (odds ratio, 7.69; P = 0.01) independently increased the risk of an incomplete functional recovery.

LIMITATIONS

The study was not designed to assess absolute incidence figures or risk factors for the development of GNP in children.

CONCLUSIONS

GNP is a significant complication of long-term peritoneal dialysis therapy in children, and a substantial proportion of affected children are at risk of permanent sequelae. Because results of empiric treatment with ceftazidime are suboptimal in the setting of this infection, alternative antimicrobial agents should be reconsidered.

Coagulase negative staphylococcal peritonitis in peritoneal dialysis patients: review of 232 consecutive cases

BACKGROUND AND OBJECTIVES

Coagulase-negative Staphylococcus species is the most common cause of peritoneal dialysis-related peritonitis; however, the optimal treatment strategy of coagulase-negative Staphylococcus species peritonitis remains controversial.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All of the coagulase-negative Staphylococcus species peritonitis in a dialysis unit from 1995 to 2006 were reviewed. During this period, there were 2037 episodes of peritonitis recorded; 232 episodes (11.4%) in 155 patients were caused by coagulase-negative Staphylococcus species.

RESULTS

The overall primary response rate was 95.3%; the complete cure rate was 71.1%. Patients with a history of recent hospitalization or recent antibiotic therapy had a higher risk for developing methicillin-resistant strains. Episodes that were treated initially with cefazolin or vancomycin had similar primary response rate and complete cure rate. There were 33 (14.2%) episodes of relapse and 29 (12.5%) episodes of repeat peritonitis; 12 (60.6%) of the repeat episodes developed within 3 mo after completion of antibiotics. Relapse or repeat episodes had a significantly lower complete cure rate than the other episodes. For relapse or repeat episodes, treatment with effective antibiotics for 3 wk was associated with a significantly higher complete cure rate than the conventional 2-wk treatment.

CONCLUSIONS

Coagulase-negative Staphylococcus species peritonitis remains a common complication of peritoneal dialysis. Methicillin resistance is common, but the treatment outcome remains favorable when cefazolin is used as the first-line antibiotic. A 3-wk course of antibiotic can probably achieve a higher cure rate in relapse or repeat episodes.

Rapid detection of causative pathogen of peritonitis using in-situ hybridization in a patient with continuous ambulatory peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) peritonitis is a common problem in patients on peritoneal dialysis, and the bacteriological diagnosis is important for the treatment of this condition. We used Hybrizep (a method for detecting the genes of bacteria ingested in phagocytes), to detect the causative bacterium in a 50-year-old woman receiving peritoneal dialysis who was admitted our hospital with bacterial peritonitis. The test, using peritoneal dialysis fluid, was positive for Streptococcus epidermidis. Vancomycin administration led to a good outcome for this patient. The Hybrizep method (which is available on the Japanese National Health system only for the diagnosis of septicemia) was a useful diagnostic approach for a patient on peritoneal dialysis who had peritonitis.

Peritonitis in children who receive long-term peritoneal dialysis: a prospective evaluation of therapeutic guidelines

In children who are on chronic peritoneal dialysis, peritonitis is the primary complication compromising technique survival, and the optimal therapy of peritonitis remains uncertain. An Internet-based International Pediatric Peritonitis Registry was established in 47 pediatric centers from 14 countries to evaluate the efficacy and safety of largely opinion-based peritonitis treatment guidelines in which empiric antibiotic therapy was stratified by disease severity. Among a total of 491 episodes of nonfungal peritonitis entered into the registry, Gram-positive organisms were cultured in 44%, Gram-negative organisms were cultured in 25%, and cultures remained negative in 31% of the episodes. In vitro evaluation revealed 69% sensitivity of Gram-positive organisms to a first-generation cephalosporin and 80% sensitivity of Gram-negative organisms to a third-generation cephalosporin. Neither the risk factors assumed by the guidelines nor the choice of empiric therapy was predictive of either the early treatment response or the final functional outcome of the peritonitis episodes. Overall, 89% of cases achieved full functional recovery, a portion after relapsing peritonitis (9%). These data serve as the basis for new evidence-based guidelines. Modification of empiric therapy to include aminoglycosides should be considered.

Factors Contributing to the Differences in Peritonitis Rates between Centers and Regions

Despite improvements in connectology, peritoneal dialysis (PD)–associated peritonitis contributes significantly to morbidity and modality failure in patients maintained on PD therapy. A broad spectrum of organisms—gram-positive, gram-negative, fungal, anaerobic—are involved in this complication. In addition, a significant percentage of episodes involve polymicrobial and culture-negative infection. Technological advances are being developed to minimize the incidence of access-related complications such as peritonitis. Many traditional factors such as exit-site infection and poor technique have been already identified. In the present review, we discuss the geographic, patient selection, and clinical issues that can affect peritonitis rates in different areas of the world and in different centers in the same area.

Microbiology and outcomes of peritonitis in North America

A proper understanding of the patterns of occurrence of infectious complications in patients on peritoneal dialysis (PD) is crucial to lay the foundation for interventions directed at the major causes and predisposing factors. The present work is an initial report of a survey based on a large representative database of the infectious complications of PD. Gram-positive organisms accounted for 62% of peritonitis episodes in the US and 61% of these episodes in Canada. Gram-negative organisms accounted for 20.5% of episodes in the US and 23.6% of episodes in Canada. The peritoneal catheter was removed in 18% of the episodes in the US and 16% in Canada. Less than 4% of the episodes resulted in death. Gram-positive organisms accounted for the majority of exit-site infections in the US (69%) and Canada (76%). Gram-negative organisms accounted for a third of exit-site infections and among Gram-negative organisms Pseudomonas was the overwhelmingly dominant organism. The microbiology of exit-site infections revealed the expected representation of Gram-positive organisms. An important finding, however, is the significantly high contribution of Gram-negative organisms. Our findings can inform future guideline development and suggest that similar endeavors be undertaken in other parts of the world.

Influence of peritoneal dialysis training nurses' experience on peritonitis rates

BACKGROUND

This study examined the clinical impact of peritoneal dialysis (PD) training nurses regarding Gram-positive peritonitis among incident dialysis patients.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

This study included 200 consecutive inception PD patients in a single center from September 1999 through April 2003. Effects of PD nurse trainers on the clinical outcomes of Gram-positive peritonitis were evaluated.

RESULTS

A total of 81 patients of 200 incident PD patients (mean age 56.9 yr) developed Gram-positive peritonitis. Mean Gram-positive peritonitis-free time for patients who were trained by nurses with years of experience in the lowest tertile was 58.8 mo, as compared with 47.0 mo in those who were trained by nurses within the intermediate tertile of experience (log-rank test, P = 0.044). After adjustment for diabetes and relevant coexisting medical factors, PD trainers' having > or =3 yr of experience, body mass index, and baseline serum albumin were the only independent risk factors for the time to a first Gram-positive peritonitis. Training nurses with > or =3 yr of experience was associated with more than two-fold increased likelihood of subsequent Gram-positive peritonitis, with an adjusted hazard ratio of 2.24 (95% confidence interval [CI] 1.14 to 4.41; P = 0.020). When the lowest tertile group of trainers was used as the reference group in the Cox proportional hazards regression model, the hazard ratio was 1.94 (95% CI 1.04 to 3.61) for the intermediate tertile and 2.13 (95% CI 1.12 to 4.06) for the highest tertile. Experience of the PD trainers was not predictive of Gram-negative peritonitis.

CONCLUSIONS

The finding of negative association between the trainers' length of time in practice and peritonitis incidence reminds us that active continued learning and applying principles of adult learning might be the answers for the nurses to teach the patients.

Diagnosis and management of enteric disease and abdominal catastrophe in peritoneal dialysis patients with peritonitis

Peritoneal dialysis (PD)-associated peritonitis rates have decreased significantly in recent years, especially Staphylococcus epidermidis and Staphylococcus aureus infections. Rates of gram-negative, polymicrobial, and fungal peritonitis have remained steady. The reported mortality of gram-negative and polymicrobial peritonitis varies widely (4%-50%). Most likely, the reason for this variability is that prognosis depends on the underlying etiology more than the specific microorganisms isolated. Gram-negative, polymicrobial, and fungal infection have variable association with documented visceral disease, and the highest mortality occurs in reports with the highest prevalence of intra-abdominal pathology. The odds ratio of death in PD patients with documented abdominal catastrophe and peritonitis is reported to be 20:1 compared with all other causes. Further reductions in PD-associated peritonitis mortality are likely to depend on earlier diagnosis and better management of intra-abdominal pathology. Presentation with hypotension, sepsis, lactic acidosis, and/or elevation of peritoneal fluid amylase should raise immediate concern for "surgical" peritonitis. Suspicion for visceral disease should also be high in patients with gram-negative, polymicrobial, and fungal infection or those who fail to improve rapidly as judged by clinical signs and symptoms, cell counts, and repeat cultures. Nonlocalizing physical examination and negative or nonspecific results of abdominal computed tomography do not rule out serious intra-abdominal disease. Immediate initiation of broad antibiotic coverage including for anaerobic infection is indicated when bowel pathology is suspected. Urgent surgical consultation, with active discussion and participation by the nephrologist, is advisable when visceral pathology is suspected and the patient is unstable or fails to improve rapidly.

A survey of peritonitis and exit-site and/or tunnel infections in Japanese children on PD

To obtain data on peritonitis and exit-site and/or tunnel infections (ESI/TI) in Japanese children undergoing peritoneal dialysis (PD) from January 1999 through June 2003, we surveyed 22 members of the Japanese Study Group of Pediatric Peritoneal Dialysis (JSPPD) by questionnaire. One hundred and thirty patients were eligible. Seventy episodes of bacterial peritonitis occurred in 45 patients (0.17 episodes/patient-year), and 123 ESI/TI occurred in 60 patients (0.29 episodes/patient-year). S. aureus and MRSA were found to be the causative organisms in 39% and 13% of the peritonitis episodes, and in 59% and 20% of the ESI/TI, respectively. Tunnel infection was found in 55% of the MRSA peritonitis episodes. Eleven percent of the peritonitis episodes relapsed, and 19% needed hemodialysis. One patient died due to MRSA peritonitis. The PD catheter was removed in all fungal and 78% of MRSA peritonitis. However, the type of organism did not influence the need for catheter-related surgery for ESI/TI. Neither peritonitis nor ESI/TI was prevented by the use of a swan-neck catheter, a downward-pointing exit site, povidone iodine exit-site care, bathing instruments, or nasal mupirocin. In conclusion, MRSA peritonitis was not uncommon in children in Japan, was frequently associated with tunnel infections, and had a poor outcome. No association was found between the occurrence of infection and preventive measures previously reported as effective. Alternative approaches are needed in children, especially for MRSA.

Usefulness of 23S rRNA amplification by PCR in the detection of bacteria in CAPD peritonitis

BACKGROUND

Peritonitis is the most common complication of continuous ambulatory peritoneal dialysis (CAPD), and the spectrum of organisms causing CAPD peritonitis is broad. Polymerase chain reaction (PCR) has recently broadened its diagnostic capabilities in infectious diseases. PCR can provide a sensitive method for identifying causative infectious organisms.

METHODS

To evaluate the usefulness of 23S bacterial ribosomal RNA amplification and direct sequencing for the detection of infectious organisms, we compared PCR with bacteriological culture for the analysis of dialysates from CAPD peritonitis patients. Thirty-two samples from CAPD peritonitis patients with current antibiotic use and control samples from 30 CAPD patients without peritonitis were examined by PCR with sequencing analysis and by conventional bacteriological culture. In addition, 95 culture-positive samples and 39 culture-negative samples from CAPD peritonitis patients before antibiotic treatment were analyzed by PCR assay.

RESULTS

In the control samples from patients without CAPD peritonitis, false-positive rates were relatively rare: 3 of 30 in the PCR study and 2 of 30 in the culture study. Of the 134 CAPD peritonitis samples collected before antibiotic therapy, positive cultures were obtained in 70.9% (95/134) of them. In 75 of the culture-positive samples, the same microorganisms were confirmed by PCR assay, and the others showed discrepant results as compared with culture study. In 30 of the 39 culture-negative samples, microbial organisms were detected by PCR assay. Of the 32 samples from patients who developed CAPD peritonitis during antibiotic treatment, 17 (53.1%) were positive by PCR assay, and 5 (15.6%) were positive by culture.

CONCLUSION

Our study suggests that broad-spectrum PCR with RNA sequencing can complement culture methods in the diagnosis of CAPD peritonitis, especially in patients with previous or current antibiotic use.

Change in bacterial aetiology of peritoneal dialysis-related peritonitis over 10 years: experience from a centre in South-East Asia

This study reviewed 1787 episodes of peritoneal dialysis (PD)-related peritonitis in 544 patients between 1994 and 2003. The overall rate of peritonitis was 0.68 episodes/year of PD, but decreased from 1.10 to 0.46 episodes/year between 1994 and 2003. The incidence of peritonitis caused by coagulase-negative staphylococci declined between 1994 and 1998 from 0.21 to 0.06 episodes/year of PD, coinciding with a reduction in the use of spike PD sets. There was a 60.1% response rate to antibiotics throughout the period, but the percentage of cases that required modification of the initial empirical antibiotic regimen rose from 13.6% to 58.7%, indicating that treatment should be individualised.

Editorials: Will Peritoneal Dialysis be Left Behind?

Peritoneal dialysis (PD) enjoyed huge growth in the 1980s, followed by a rapid decline in the late 1990s, and a now persistently low utilization rate in many countries, including the United States. Recent clinical data indicate a survival advantage for patients started on PD. Residual renal function is better preserved with PD. Adequacy targets are being revised and will likely allow PD prescriptions to be simplified. The physiology of the peritoneum is better understood and treatment strategies reflect that understanding. New solutions have been developed in response to studies that have assessed the impact of conventional PD dialysate on the structure and function of the peritoneum. A remaining challenge is to ensure that nephrology trainees and nephrologists in practice are fully informed of the advantages of PD for many patients and of the advances in the therapy. If this can be achieved, PD should start to grow again.