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

Staphylococcus aureus small colony variants: A potentially underestimated microbiological challenge in peritoneal dialysis

INTRODUCTION

Peritonitis remains the major infectious complication in the setting of peritoneal dialysis (PD). Despite known only moderate pathogenicity, the most frequently detected pathogens in PD-related peritonitis are surprisingly coagulase-negative staphylococci. However, this could be explained, at least in part, by Staphylococcus aureus small colony variants (SCVs) induced by PD fluids (PDFs) and misidentified by routinely used microbiological methods.

MATERIAL AND METHODS

Bacteria were exposed to commonly used PDFs in various regimens designed to simulate daily use as closely as possible. Wild-type isolates and SCVs were subsequently used to determine minimum inhibitory concentrations (MICs), in vitro biofilm formation capacities, and auxotrophies. Underlying genetic alterations were investigated using whole-genome sequencing, and various microbial identification methods were tested to determine their performance for wild-types and SCVs.

RESULTS

Stable SCVs could be isolated most successfully after exposure to glucose-containing PDFs alone. The reading of MICs was significantly affected by the reduced growth of SCVs, resulting in lower MIC values in 44% of all tests. Nonsynonymous mutations were found in all but one SCV, while only two isolates showed typical auxotrophic responses. While MALDI-TOF, PCR and Pastorex Staph-Plus correctly identified all S. aureus SCVs, API-Staph and VITEK-2 yielded identification rates of only 40% and 10%, respectively.

CONCLUSIONS

Overall, the present study has shown that commercially available PDFs induce S. aureus SCVs in vitro, which are difficult to identify and test for antimicrobial susceptibility and can potentially lead to recurrent or persistent infections. Thus, they represent a potentially underappreciated challenge not only for microbiologists, but also for clinicians.

Persistent peritonitis in peritoneal dialysis: a comphrenesive review of recurrent, relapsing, refractory, and repeat peritonitis

Peritonitis is a major cause of morbidity and technique failure in patients receiving peritoneal dialysis. Complicated peritonitis that manifests as multiple or unresolving episodes is classified as refractory, recurrent, relapsing, or repeat peritonitis, and often possesses higher risk of technique failure and mortality as well as lower complete cure rates than primary or uncomplicated episodes. While these peritonitis subtypes affect a considerable portion of PD patients, details regarding their epidemiology, pathogenesis, diagnosis, clinical sequelae, and management have not yet been fully elucidated. Improved clinical awareness and understanding of complicated peritonitis subtypes is crucial to ensure optimal management for these patients; thus, we consolidate and report the pertinent findings of recent literature on these four entities.

Is simply washing hands before dialysis procedures sufficient for reducing peritoneal dialysis peritonitis?-A single center study from 2015 to 2020 in Yiwu, China

INTRODUCTION

The study aimed to improve the qualified rate of hand hygiene and reduce the incidence of peritonitis in peritoneal dialysis (PD) patients.

METHODS

A hand hygiene questionnaire was distributed to patients during home visits and outpatient visits in 2015 and 2020. Hand-washing practices were evaluated by collecting cultures from the hands of patients after hand washing, evaluating their household environment, and recording the antimicrobial resistance of pathogenic bacteria.

RESULTS

Compared to patients in 2015, patients in 2020 had fewer errors in hand washing (p < 0.05), but the rate of qualification after hand washing was lower (p < 0.01). Furthermore, patients who used hand disinfectants after washing had a higher qualified rate. Coagulase-negative staphylococcus (CNS) was the most common isolated bacteria. From 2015 to 2020, the annual incidence of CNS PD peritonitis did not decrease, while the proportion of methicillin-resistant CNS decreased.

CONCLUSION

The use of hand disinfectants after standard hand washing may help reduce the incidence of peritonitis in PD patients.

High C-reactive protein and number of previous episodes at diagnosis increase the risk of catheter removal in peritoneal dialysis-related peritonitis in children

BACKGROUND

A minority of patients with peritonitis require removal of peritoneal dialysis (PD) catheters. We examined risk factors at diagnosis that could predict the removal of PD catheter before obtaining the results of treatment success in children with peritonitis.

METHODS

We analyzed 156 peritonitis episodes in 57 pediatric PD patients.

RESULTS

The peritonitis rate was 0.68 peritonitis episode per patient year. Catheter removal was required in 22 of 156. C-reactive protein (CRP) ≥ ×10 of upper limit at diagnosis and increased previous episode number were found to be associated with catheter removal (OR [95% CI] 6.4 [2.3-18.1], p = 0.001 and 3.8 [1.4-10.6], p = 0.009).

CONCLUSION

These findings supported that CRP could be an early marker in predicting catheter removal even before obtaining the results of treatment success. Furthermore, it should be kept in mind that the risk of catheter removal is high in patients with high number of previous episodes especially of three or more.

Predictive Factors, Treatment, and Outcomes of Coagulase-Negative Staphylococcal Peritonitis in Malaysian Peritoneal Dialysis Patients: A Single-Center Study

Aims

Coagulase-negative Staphylococci (CoNS) are frequently isolated in peritoneal dialysis (PD)-related peritonitis with a high rate of relapse and repeat peritonitis after initial response to antimicrobials. The optimal treatment regimen for CoNS peritonitis remains debatable. Hence, this study aimed to describe the clinical and microbiologic characteristics of CoNS peritonitis in a PD center and determine predictive factors influencing the outcomes.

Methods

All cases of CoNS peritonitis in Selayang Hospital between 2011 and 2019 were reviewed retrospectively.

Results

A total of 906 episodes of peritonitis were recorded; 140 episodes (15%) in 98 patients were caused by CoNS. The oxacillin and gentamicin resistance rates were 47% and 46%, respectively. The overall primary response rate was 90%, and the complete cure rate was 79%. Patients with concomitant exit-site infection (odds ratio (OR) 0.06, 95% confidence interval (CI) 0.01 to 0.40, P < 0.01) and history of recent systemic antibiotic use (OR 0.04, 95% CI 0.01 to 0.82, P=0.04) were less likely to achieve primary response. CoNS episodes that were treated with beta-lactam-based or vancomycin-based therapy had a similar primary response rate and complete cure rate. The rates of relapse and repeat were 12% and 16%, respectively. Relapsed episodes (OR 0.35, 95% CI 0.13 to 0.97, P=0.04) had a significantly lower complete cure rate than the first episodes.

Conclusion

Relapsed CoNS peritonitis was common and was associated with worse outcomes than the first episode of CoNS peritonitis. Oxacillin resistance was common, but the treatment outcome remained favourable when a beta-lactam-based regimen was used as empirical therapy.

ISPD peritonitis guideline recommendations: 2022 update on prevention and treatment

Peritoneal dialysis (PD)-associated peritonitis is a serious complication of PD and prevention and treatment of such is important in reducing patient morbidity and mortality. The ISPD 2022 updated recommendations have revised and clarified definitions for refractory peritonitis, relapsing peritonitis, peritonitis-associated catheter removal, PD-associated haemodialysis transfer, peritonitis-associated death and peritonitis-associated hospitalisation. New peritonitis categories and outcomes including pre-PD peritonitis, enteric peritonitis, catheter-related peritonitis and medical cure are defined. The new targets recommended for overall peritonitis rate should be no more than 0.40 episodes per year at risk and the percentage of patients free of peritonitis per unit time should be targeted at >80% per year. Revised recommendations regarding management of contamination of PD systems, antibiotic prophylaxis for invasive procedures and PD training and reassessment are included. New recommendations regarding management of modifiable peritonitis risk factors like domestic pets, hypokalaemia and histamine-2 receptor antagonists are highlighted. Updated recommendations regarding empirical antibiotic selection and dosage of antibiotics and also treatment of peritonitis due to specific microorganisms are made with new recommendation regarding adjunctive oral N-acetylcysteine therapy for mitigating aminoglycoside ototoxicity. Areas for future research in prevention and treatment of PD-related peritonitis are suggested.

Poorer clinical outcomes of early-onset peritonitis in elderly peritoneal dialysis patients: A longitudinal and multicenter study

INTRODUCTION

Early-onset peritonitis (EOP) is a risk factor for mortality in peritoneal dialysis (PD) patients. This study investigates the clinical features and outcomes of EOP in elderly patients.

METHODS

This multicenter retrospective study evaluated 433 elderly PD patients with end-stage renal disease. The cohort was divided into nonperitonitis group (n = 239), EOP group (≤12 months, n = 109) and late-onset peritonitis (LOP) group (>12 months, n = 85). Clinical data, treatment results, and outcomes were compared between the groups.

RESULTS

Compared with LOP group, there were no significant intergroup differences in the rate of primary recovery, complete cure, relapse, catheter removal, or death from PDAP (p >0.05) in the most recent PDAP episode. However, Kaplan-Meier analysis showed that patients in the EOP group were likely to have multiple episodes of PD-associated peritonitis (PDAP), technique failure, all-cause death, and composite endpoint in the long-term prognostic outcomes (p <0.001).

CONCLUSIONS

EOP is significantly associated with poorer clinical outcomes in older PD patients.

Peritoneal Dialysis Guidelines 2019 Part 1 (Position paper of the Japanese Society for Dialysis Therapy)

Approximately 10 years have passed since the Peritoneal Dialysis Guidelines were formulated in 2009. Much evidence has been reported during the succeeding years, which were not taken into consideration in the previous guidelines, e.g., the next peritoneal dialysis PD trial of encapsulating peritoneal sclerosis (EPS) in Japan, the significance of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), the effects of icodextrin solution, new developments in peritoneal pathology, and a new international recommendation on a proposal for exit-site management. It is essential to incorporate these new developments into the new clinical practice guidelines. Meanwhile, the process of creating such guidelines has changed dramatically worldwide and differs from the process of creating what were “clinical practice guides.” For this revision, we not only conducted systematic reviews using global standard methods but also decided to adopt a two-part structure to create a reference tool, which could be used widely by the society’s members attending a variety of patients. Through a working group consensus, it was decided that Part 1 would present conventional descriptions and Part 2 would pose clinical questions (CQs) in a systematic review format. Thus, Part 1 vastly covers PD that would satisfy the requirements of the members of the Japanese Society for Dialysis Therapy (JSDT). This article is the duplicated publication from the Japanese version of the guidelines and has been reproduced with permission from the JSDT.

Variation in Peritoneal Dialysis-Related Peritonitis Outcomes in the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS)

RATIONALE & OBJECTIVE

Peritoneal dialysis (PD)-associated peritonitis is a significant PD-related complication. We describe the likelihood of cure after a peritonitis episode, exploring its association with various patient, peritonitis, and treatment characteristics.

STUDY DESIGN

Observational prospective cohort study.

SETTING & PARTICIPANTS

1,631 peritonitis episodes (1,190 patients, 126 facilities) in Australia, New Zealand, Canada, Japan, Thailand, the United Kingdom, and the United States.

EXPOSURE

Patient characteristics (demographics, patient history, laboratory values), peritonitis characteristics (organism category, concomitant exit-site infection), dialysis center characteristics (use of icodextrin and low glucose degradation product solutions, policies regarding antibiotic self-administration), and peritonitis treatment characteristics (antibiotic used).

OUTCOME

Cure, defined as absence of death, transfer to hemodialysis (HD), PD catheter removal, relapse, or recurrent peritonitis within 50 days of a peritonitis episode.

ANALYTICAL APPROACH

Mixed-effects logistic models.

RESULTS

Overall, 65% of episodes resulted in a cure. Adjusted odds ratios (AOR) for cure were similar across countries (range, 54%-68%), by age, sex, dialysis vintage, and diabetes status. Compared with Gram-positive peritonitis, the odds of cure were lower for Gram-negative (AOR, 0.41 [95% CI, 0.30-0.57]), polymicrobial (AOR, 0.30 [95% CI, 0.20-0.47]), and fungal (AOR, 0.01 [95% CI, 0.00-0.07]) peritonitis. Odds of cure were higher with automated PD versus continuous ambulatory PD (AOR, 1.36 [95% CI, 1.02-1.82]), facility icodextrin use (AOR per 10% greater icodextrin use, 1.06 [95% CI, 1.01-1.12]), empirical aminoglycoside use (AOR, 3.95 [95% CI, 1.23-12.68]), and ciprofloxacin use versus ceftazidime use for Gram-negative peritonitis (AOR, 5.73 [95% CI, 1.07-30.61]). Prior peritonitis episodes (AOR, 0.85 [95% CI, 0.74-0.99]) and concomitant exit-site infection (AOR, 0.41 [95% CI, 0.26-0.64]) were associated with a lower odds of cure.

LIMITATIONS

Sample selection may be biased and generalizability may be limited. Residual confounding and confounding by indication limit inferences. Use of facility-level treatment variables may not capture patient-level treatments.

CONCLUSIONS

Outcomes after peritonitis vary by patient characteristics, peritonitis characteristics, and modifiable peritonitis treatment practices. Differences in the odds of cure across infecting organisms and antibiotic regimens suggest that organism-specific treatment considerations warrant further investigation.

Comparison of clinical features and outcomes in peritoneal dialysis-associated peritonitis patients with and without diabetes: A multicenter retrospective cohort study

BACKGROUND

The number of end-stage renal disease patients with diabetes mellitus (DM) who are undergoing peritoneal dialysis is increasing. Peritoneal dialysis-associated peritonitis (PDAP) is a serious complication of peritoneal dialysis leading to technical failure and increased mortality in patients undergoing peritoneal dialysis. The profile of clinical symptoms, distribution of pathogenic organisms, and response of PDAP to medical management in the subset of end-stage renal disease patients with DM have not been reported previously. Discrepant results have been found in long-term prognostic outcomes of PDAP in patients with DM. We inferred that DM is associated with bad outcomes in PDAP patients.

AIM

To compare the clinical features and outcomes of PDAP between patients with DM and those without.

METHODS

In this multicenter retrospective cohort study, we enrolled patients who had at least one episode of PDAP during the study period. The patients were followed for a median of 31.1 mo. They were divided into a DM group and a non-DM group. Clinical features, therapeutic outcomes, and long-term prognostic outcomes were compared between the two groups. Risk factors associated with therapeutic outcomes of PDAP were analyzed using multivariable logistic regression. A Cox proportional hazards model was constructed to examine the influence of DM on patient survival and incidence of technical failure.

RESULTS

Overall, 373 episodes occurred in the DM group (n = 214) and 692 episodes occurred in the non-DM group (n = 395). The rates of abdominal pain and fever were similar in the two groups (P > 0.05). The DM group had more infections with coagulase-negative Staphylococcus and less infections with Escherichia coli (E. coli) as compared to the non-DM group (P < 0.05). Multivariate logistic regression analysis revealed no association between the presence of diabetes and rates of complete cure, catheter removal, PDAP-related death, or relapse of PDAP (P > 0.05). Patients in the DM group were older and had a higher burden of cardiovascular disease, with lower level of serum albumin, but a higher estimated glomerular filtration rate (P < 0.05). Cox proportional hazards model confirmed that the presence of diabetes was a significant predictor of all-cause mortality (hazard ratio = 1.531, 95% confidence interval: 1.091-2.148, P < 0.05), but did not predict the occurrence of technical failure (P > 0.05).

CONCLUSION

PDAP patients with diabetes have similar symptomology and are predisposed to coagulase-negative Staphylococcus but not E. coli infection compared those without. Diabetes is associated with higher all-cause mortality but not therapeutic outcomes of PDAP.

IncreasingStaphylococcusSpecies Resistance in Peritoneal Dialysis-Related Peritonitis Over a 10-Year Period in a Single Taiwanese Center

Background

Peritonitis is a major complication of peritoneal dialysis (PD). Staphylococcus species are gram-positive bacteria that are most commonly associated with peritoneal peritonitis. The increasing antimicrobial resistance rate is a severe burden when considering the initial choice of antibiotics. This investigation examined the trends of staphylococcal infection as well as the resistance rate and clinical outcomes from 2006 to 2015 in southern Taiwan.

Methods

We retrospectively investigated all PD-related peritonitis episodes in southern Taiwan between January 2006 and December 2015 and evaluated the clinical characteristics of peritonitis, microbiological prevalence and resistance of Staphylococcus species, and outcomes in patients.

Results

Among 244 episodes of peritonitis, Staphylococcus species accounted for approximately 65% of the gram-positive bacteria that caused the infection. The methicillin resistance rate among Staphylococcus species substantially increased to 64% by 2015 in both Staphylococcus aureus and coagulase-negative staphylococci in southern Taiwan. Notably, patients with methicillin-resistant staphylococcal infection exhibited a significantly higher hospitalization rate than those with methicillin-sensitive staphylococcal infection. However, the catheter removal rate and transfer to hemodialysis exhibited no differences between the 2 groups.

Conclusion

Peritonitis is the most serious complication in patients on PD, and microbiological trends have changed over the past 10 years at a single center in southern Taiwan. The number of methicillin-resistant Staphylococcus species has substantially increased. Empirical initial antibiotic therapy should be adapted on the basis of the growing microbiological resistance.

Outcomes of Acinetobacter Peritonitis in Peritoneal Dialysis Patients: A Multicenter Registry Analysis

Background

Acinetobacter is a rare but important cause of peritonitis in peritoneal dialysis (PD) patients. As the complication has not been comprehensively evaluated previously, the present study examined the outcomes of Acinetobacter peritonitis in a large, national cohort of PD patients.

Methods

The study included all episodes of peritonitis in Australia from January 2004 to December 2014 using Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) data. The primary outcome was peritonitis cure and secondary outcomes were catheter removal, hemodialysis transfer, recurrent/relapsing peritonitis, peritonitis-related hospitalization, and death. Outcomes were compared using multivariable logistic regression.

Results

Overall, 5,367 patients experienced 11,122 episodes of peritonitis across 51 centers in Australia. Of these, 228 (4.2%) patients experienced 253 (2.3%) episodes of Acinetobacter peritonitis (176 episodes were due to Acinetobacter alone and 77 involved co-infection with other organisms). Of the 176 solitary Acinetobacter episodes, 131(74%) achieved cure with antibiotics alone. Compared with Acinetobacter, significantly lower odds of peritonitis cure were observed for Pseudomonas (adjusted odds ratio [AOR] 0.24, 95% confidence interval [CI]: 0.16 – 0.36), other gram-negative organisms (AOR 0.54, 95% CI 0.37 – 0.77), fungi (AOR 0.02, 95% CI 0.01 – 0.03), and polymicrobial organisms (AOR 0.36, 95% CI 0.25 – 0.51), whilst similar odds of cure were observed for Staphylococcus (AOR 0.73, 95% CI 0.50 – 1.06), other gram-positive organisms (AOR 1.32,95% CI 0.93 – 1.89), culture-negative (AOR 1.19, 95% CI 0.82 –1.71), and other organisms (AOR 0.72, 95% CI 0.49 – 1.07). The odds of catheter removal and hemodialysis transfer were higher with Pseudomonas, other gram-negative, fungal, and polymicrobial peritonitis than with Acinetobacter peritonitis. The odds of death were also higher with Pseudomonas and fungal peritonitis than with Acinetobacter peritonitis. Treatment of Acinetobacter peritonitis with gentamicin, ciprofloxacin, or ceftazidime achieved comparable outcomes.

Conclusions

Outcomes of Acinetobacter peritonitis were favorable compared with most other forms of organism-specific peritonitis. Commonly used antibiotics covering gram-negative bacteria achieved comparable outcomes in Acinetobacter peritonitis.

Peritoneal dialysis-related peritonitis: challenges and solutions

Peritoneal dialysis is an effective treatment modality for patients with end-stage renal disease. The relative use of peritoneal dialysis versus hemodialysis varies widely by country. Data from a 2004 survey reports the percentage of patients with end-stage renal disease treated with peritoneal dialysis to be 5%-10% in economically developed regions like the US and Western Europe to as much as 75% in Mexico. This disparity is probably related to the availability and access to hemodialysis, or in some cases patient preference for peritoneal over hemodialysis. Peritoneal dialysis-related peritonitis remains the major complication and primary challenge to the long-term success of peritoneal dialysis. Fifty years ago, with the advent of the Tenckhoff catheter, patients averaged six episodes of peritonitis per year on peritoneal dialysis. In 2016, the International Society for Peritoneal Dialysis proposed a benchmark of 0.5 episodes of peritonitis per year or one episode every 2 years. Despite the marked reduction in peritonitis over time, peritonitis for the individual patient is problematic. The mortality for an episode of peritonitis is 5% and is a cofactor for mortality in another 16% of affected patients. Prevention of peritonitis and prompt and appropriate management of peritonitis is essential for the long-term success of peritoneal dialysis in all patients. In this review, challenges and solutions are addressed regarding the pathogenesis, clinical features, diagnosis, treatment, and prevention of peritoneal dialysis-related peritonitis from the viewpoint of an infectious disease physician.

Acute Peritonitis Caused by Staphylococcus capitis in a Peritoneal Dialysis Patient

Acute peritonitis remains the most common complication of peritoneal dialysis (PD), with coagulase-negative staphylococci (CoNS) reported to account for more than 25% of peritonitis episodes (1). Staphylococcus capitis is a gram-positive, catalase-positive CoNS that was originally identified as a commensal on the skin of the human scalp (2). Advancement of microbiological technologies for bacterial identification enables diagnosis of previously unknown causes of acute peritonitis. This is the first reported case of acute peritonitis in a PD patient caused by S. capitis.

Machine-learning algorithms define pathogen-specific local immune fingerprints in peritoneal dialysis patients with bacterial infections

The immune system has evolved to sense invading pathogens, control infection, and restore tissue integrity. Despite symptomatic variability in patients, unequivocal evidence that an individual's immune system distinguishes between different organisms and mounts an appropriate response is lacking. We here used a systematic approach to characterize responses to microbiologically well-defined infection in a total of 83 peritoneal dialysis patients on the day of presentation with acute peritonitis. A broad range of cellular and soluble parameters was determined in peritoneal effluents, covering the majority of local immune cells, inflammatory and regulatory cytokines and chemokines as well as tissue damage–related factors. Our analyses, utilizing machine-learning algorithms, demonstrate that different groups of bacteria induce qualitatively distinct local immune fingerprints, with specific biomarker signatures associated with Gram-negative and Gram-positive organisms, and with culture-negative episodes of unclear etiology. Even more, within the Gram-positive group, unique immune biomarker combinations identified streptococcal and non-streptococcal species including coagulase-negative Staphylococcus spp. These findings have diagnostic and prognostic implications by informing patient management and treatment choice at the point of care. Thus, our data establish the power of non-linear mathematical models to analyze complex biomedical datasets and highlight key pathways involved in pathogen-specific immune responses.

Effect of UV Light on Disinfection of Peritoneal Dialysis Catheter Connections

We evaluated the microbiological performance of an ultraviolet (UV) light-based peritoneal dialysis catheter connection system. The system includes a UV light-generating device combined with a UV transmissive window incorporated into the transfer set. Each UV transparent transfer set was inoculated with 10 μL of cultured inoculum consisting of either S. aureus, E. coli, or C. albicans After being inoculated, we attached a solution set connector to the transfer catheter, and exposed that connection to a UV light dose of approximately 340 mJoules/cm² After exposure to UV light, we broke the seal of the solution set and opened the plunger valve on the UV transmissive transfer catheter. We then flushed 10 mL of dialysate through the connection. The flushed solution was collected, diluted, plated on agar medium, and incubated for 24 hours. Results were compared to positive controls collected in an identical manner without exposure to UV light. Thirty test samples and 3 positive controls were collected for each organism. All test samples exposed to UV light had complete kill of bacteria except 1 colony on a single plate in the S. aureus group. Mean log reduction was 4.03 for C. albicans, 4.73 for S. aureus, and 5.29 for E. coli All positive control samples had significant bacterial growth. Our results demonstrate that the application of UV light within a UV transmissive transfer catheter window produces a germicidal effect upon microorganisms known to be associated with peritonitis.

The Current State of Peritoneal Dialysis

Technical innovations in peritoneal dialysis (PD), now used widely for the long-term treatment of ESRD, have significantly reduced therapy-related complications, allowing patients to be maintained on PD for longer periods. Indeed, the survival rate for patients treated with PD is now equivalent to that with in-center hemodialysis. In parallel, changes in public policy have spurred an unprecedented expansion in the use of PD in many parts of the world. Meanwhile, our improved understanding of the molecular mechanisms involved in solute and water transport across the peritoneum and of the pathobiology of structural and functional changes in the peritoneum with long-term PD has provided new targets for improving efficiency and for intervention. As with hemodialysis, almost half of all deaths on PD occur because of cardiovascular events, and there is great interest in identifying modality-specific factors contributing to these events. Notably, tremendous progress has been made in developing interventions that substantially reduce the risk of PD-related peritonitis. Yet the gains have been unequal among individual centers, primarily because of unequal clinical application of knowledge gained from research. The work to date has further highlighted the areas in need of innovation as we continue to strive to improve the health and outcomes of patients treated with PD.

Unconventional Human T Cells Accumulate at the Site of Infection in Response to Microbial Ligands and Induce Local Tissue Remodeling

The antimicrobial responsiveness and function of unconventional human T cells are poorly understood, with only limited access to relevant specimens from sites of infection. Peritonitis is a common and serious complication in individuals with end-stage kidney disease receiving peritoneal dialysis. By analyzing local and systemic immune responses in peritoneal dialysis patients presenting with acute bacterial peritonitis and monitoring individuals before and during defined infectious episodes, our data show that Vγ9/Vδ2⁺ γδ T cells and mucosal-associated invariant T cells accumulate at the site of infection with organisms producing (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate and vitamin B₂, respectively. Such unconventional human T cells are major producers of IFN-γ and TNF-α in response to these ligands that are shared by many microbial pathogens and affect the cells lining the peritoneal cavity by triggering local inflammation and inducing tissue remodeling with consequences for peritoneal membrane integrity. Our data uncover a crucial role for Vγ9/Vδ2 T cells and mucosal-associated invariant T cells in bacterial infection and suggest that they represent a useful predictive marker for important clinical outcomes, which may inform future stratification and patient management. These findings are likely to be applicable to other acute infections where local activation of unconventional T cells contributes to the antimicrobial inflammatory response.

Difficult peritonitis cases in children undergoing chronic peritoneal dialysis: relapsing, repeat, recurrent and zoonotic episodes

Despite technological improvements in dialysis connectology and dialysis technique, peritonitis remains the most common and most significant complication of peritoneal dialysis (PD) in children. Most children undergoing chronic PD experience none or only one peritonitis episode, while others have multiple episodes or episodes secondary to unusual organisms. Knowledge of potential risk factors and likely patient outcome is imperative if treatment is to be optimized. In this review we will, in turn, describe episodes of peritonitis that are characterized as either relapsing, recurrent, repeat or zoonosis-related to highlight the clinical issues that are commonly encountered by clinicians treating these infections.

Lack of motivation: a new modifiable risk factor for peritonitis in patients undergoing peritoneal dialysis?

AIM

Can we identify modifiable risk factors for peritonitis in patients undergoing peritoneal dialysis (PD)? We aimed to determine whether housing standard, PD exchange technique or patient motivation might be modifiable risks for peritonitis. We also explored the relationship between lack of motivation and depression.

METHODS

Nurse home visits assessed PD exchange technique, environment and patient motivation. Motivation scores were correlated separately with an Apathy Evaluation Score and a depression score using PHQ-9 questionnaires.

RESULTS

Home hygiene, exchange technique and motivation were above average in 53%, 56% and 60%, respectively in 104 patients undergoing PD. After 15 months, 25.9% patients developed peritonitis but nurses' ratings of homes and exchange techniques were not predictive. Low patient motivation was predictive. Patients rated to have above or below median motivation had significantly different Apathy Scores (p = 0.0002). Unmotivated depressed patients were significantly more likely to develop peritonitis compared to motivated depressed patients.

CONCLUSION

Lack of motivation predicted peritonitis particularly if associated with depression. Further studies are required focusing on specific motivation scoring schemes and the psychosocial support that might lead to better outcomes.

Efficacy of antibiotic therapy for peritoneal dialysis-associated peritonitis: a proportional meta-analysis

Background

The choice of antimicrobials for initial treatment of peritoneal dialysis (PD)-related peritonitis is crucial for a favorable outcome. There is no consensus about the best therapy; few prospective controlled studies have been published, and the only published systematic reviews did not report superiority of any class of antimicrobials. The objective of this review was to analyze the results of PD peritonitis treatment in adult patients by employing a new methodology, the proportional meta-analysis.

Methods

A review of the literature was conducted. There was no language restriction. Studies were obtained from MEDLINE, EMBASE, and LILACS. The inclusion criteria were: (a) case series and RCTs with the number of reported patients in each study greater than five, (b) use of any antibiotic therapy for initial treatment (e.g., cefazolin plus gentamicin or vancomycin plus gentamicin), for Gram-positive (e.g., vancomycin or a first generation cephalosporin), or for Gram-negative rods (e.g., gentamicin, ceftazidime, and fluoroquinolone), (c) patients with PD-related peritonitis, and (d) studies specifying the rates of resolution. A proportional meta-analysis was performed on outcomes using a random-effects model, and the pooled resolution rates were calculated.

Results

A total of 64 studies (32 for initial treatment and negative culture, 28 reporting treatment for Gram-positive rods and 24 reporting treatment for Gram-negative rods) and 21 RCTs met all inclusion criteria (14 for initial treatment and negative culture, 8 reporting treatment for Gram-positive rods and 8 reporting treatment for Gram-negative rods). The pooled resolution rate of ceftazidime plus glycopeptide as initial treatment (pooled proportion = 86% [95% CI 0.82–0.89]) was significantly higher than first generation cephalosporin plus aminoglycosides (pooled proportion = 66% [95% CI 0.57–0.75]) and significantly higher than glycopeptides plus aminoglycosides (pooled proportion = 75% [95% CI 0.69–0.80]. Other comparisons of regimens used for either initial treatment, treatment for Gram-positive rods or Gram-negative rods did not show statistically significant differences.

Conclusion

We showed that the association of a glycopeptide plus ceftazidime is superior to other regimens for initial treatment of PD peritonitis. This result should be carefully analyzed and does not exclude the necessity of monitoring the local microbiologic profile in each dialysis center to choice the initial therapeutic protocol.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-445) contains supplementary material, which is available to authorized users.

Peritoneal dialysis-related peritonitis: towards improving evidence, practices, and outcomes

Peritonitis is a common serious complication of peritoneal dialysis that results in considerable morbidity, mortality, and health care costs. It also significantly limits the use of this important dialysis modality. Despite its importance as a patient safety issue, peritonitis practices and outcomes vary markedly and unacceptably among different centers, regions, and countries. This article reviews peritonitis risk factors, diagnosis, treatment, and prevention, particularly focusing on potential drivers of variable practices and outcomes, controversial or unresolved areas, and promising avenues warranting further research. Potential strategies for augmenting the existing limited evidence base and reducing the gap between evidence-based best practice and actual practice also are discussed.

Peritoneal dialysis-related peritonitis due to coagulase-negative Staphylococcus: a review of 115 cases in a Brazilian center

BACKGROUND AND OBJECTIVES

Coagulase-negative Staphylococcus (CNS) is the most frequent cause of peritoneal dialysis (PD)-related peritonitis in many centers. This study aimed to describe clinical and microbiologic characteristics of 115 CNS episodes and to determine factors influencing the outcome.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study reviewed the records of 115 CNS peritonitis episodes that occurred in 74 patients between 1994 and 2011 at a single university center. Peritonitis incidences were calculated for three consecutive 6-year periods (P1, 1994-1999; P2, 2000-2005; P3, 2006-2011) and annually. The production of biofilms, enzymes, and toxins was evaluated. Oxacillin resistance was evaluated based on its minimum inhibitory concentration and the presence of the mecA gene.

RESULTS

The overall incidence of CNS peritonitis was 0.15 episodes per patient per year and did not vary over time (0.12, 0.14, and 0.16 for P1, P2, and P3, respectively; P=0.21). The oxacillin resistance rate was 69.6%. Toxin and enzyme production was infrequent and 36.5% of CNS strains presented the gene encoding biofilm production. The presence of icaAD genes associated with biofilm production was predictive of relapses or repeat episodes (odds ratio [OR], 2.82; 95% confidence interval [95% CI], 1.11 to 7.19; P=0.03). Overall, 70 episodes (60.9%) resolved; oxacillin susceptibility (OR, 4.41; 95% CI, 1.48 to 13.17; P=0.01) and vancomycin use as the first treatment (OR, 22.27; 95% CI, 6.16 to 80.53; P<0.001) were the only independent predictors of resolution.

CONCLUSIONS

Oxacillin resistance and vancomycin use as the first treatment strongly influence the resolution rate in CNS peritonitis, which reinforces the validity of the International Society for Peritoneal Dialysis guidelines on monitoring bacterial resistance to define protocols for initial treatment. These results also suggest that the presence of biofilm is a potential cause of repeat peritonitis episodes.

Peritoneal dialysis outcomes after temporary haemodialysis transfer for peritonitis

BACKGROUND

There has not been a comprehensive examination to date of peritoneal dialysis (PD) outcomes after temporary haemodialysis (HD) transfer for peritonitis.

METHODS

The study included all incident Australian patients who experienced peritonitis between 1 October 2003, and 31 December 2011, using Australia and New Zealand Dialysis and Transplant Registry data. Patients were grouped into three categories: Interim HD, Permanent HD and Never HD based on HD transfer status after the first peritonitis. The independent predictors of HD transfer and subsequent return to PD were determined by multivariable, multilevel mixed-effects logistic regression analysis. Matched case-control analyses were performed to compare clinical outcomes (e.g. patient survival) between groups.

RESULTS

Of the 3305 patients who experienced peritonitis during the study period, 553 episodes (16.7%) resulted in transfer to HD and 101 patients subsequently returned to PD. HD transfer was significantly and independently predicted by inpatient treatment of peritonitis [odds ratio (OR) 11.45, 95% confidence interval (CI) 7.14-18.36] and the recovered microbiologic profile of organisms recognized to be associated with moderate (20-40%) to high (>40%) rates of catheter removal (moderate: OR 2.45, 95% CI 1.89-3.17; high: OR 8.63, 95% CI 6.44-11.57). Matched case-control analyses yielded comparable results among Interim, Permanent and Never HD groups in terms of patient survival (P = 0.28), death-censored technique survival [hazard ratio (HR) 0.87, 95% CI 0.59-1.28; P = 0.48] and peritonitis-free survival (HR 0.84, 95% CI 0.50-1.39, P = 0.49).

CONCLUSIONS

In an observational registry study of first peritonitis episodes, temporary HD transfer was not associated with inferior patient-level clinical outcomes when compared with others who either never required HD transfer or remained on HD permanently if all patient-level and peritonitis-related factors were considered equal. Therefore, return to PD after a temporary HD due to peritonitis should not be discouraged in appropriate PD patients.

Novel predictors of peritonitis-related outcomes in the BRAZPD cohort

INTRODUCTION

Peritonitis remains the main cause of peritoneal dialysis (PD) technique failure worldwide, despite significant reductions in infection rates observed over the past decades. Several studies have described risk factors for peritonitis, technique failure and mortality. However, there are scarce data regarding predictors of complications during and after a peritonitis episode. The aim of our study was to analyze predictors of peritonitis-related outcome in the Brazilian Peritoneal Dialysis study (BRAZPD) cohort.

METHODS

All adult incident patients recruited in the BRAZPD Study between December 2004 and October 2007, who remained at least 90 days on PD and presented their first peritonitis episode (n = 474 patients) were included in the study. The endpoints analyzed were non-resolution, death due to a peritonitis episode and long-term technique survival after a peritonitis episode.

RESULTS

In the multivariable regression, non-resolution was independently associated with older age (odds ratio (OR) 1.02; p < 0.01), collagenosis as the primary renal disease (OR 4.6; p < 0.05) and Pseudomonas spp as etiological agent (OR 2.9; p < 0.05). Patients who were transferred from APD to CAPD during peritonitis therapy presented a higher risk of non-response (OR 2.5; p < 0.05). The only factor associated with death during a peritonitis episode was older age (OR 1.04; p < 0.05). Exposure to vancomycin and male gender were the independent predictors of long-term technique failure (OR 2.2; p < 0.01).

CONCLUSION

Apart from confirming previous observations of the negative impact of older age and Pseudomonas spp peritonitis on outcomes, we observed that collagenosis may negatively impact response to treatment and exposure to vancomycin may possibly reduce long-term technique survival. It is important to emphasize that the association of vancomycin with technique failure does not prove causality. These findings shed light on new factors predicting outcome when peritonitis is diagnosed.

Correlation between glycemic control and the incidence of peritoneal and catheter tunnel and exit-site infections in diabetic patients undergoing peritoneal dialysis

BACKGROUND

Diabetes mellitus, especially if complicated by poor glycemic control, portends an increased risk of infection. The significance of this association in the case of diabetic patients undergoing peritoneal dialysis (PD) has not been assessed.

METHODS

Using a retrospective observational design, we analyzed the association between glycemic control at the start of PD (estimated from glycosylated hemoglobin levels) and the risk of peritoneal and catheter tunnel and exit-site infections during follow-up in 183 incident patients on PD. We used the median value of glycosylated hemoglobin to classify patients into good (group A) or poor (group B) glycemic control groups. We applied multivariate strategies of analysis to control for other potential predictors of PD-related infection.

RESULTS

Groups A and B differed significantly in age, dialysis vintage, use of insulin, and rate of Staphylococcus aureus carriage. Neither the incidence (0.60 episodes in group A vs 0.56 episodes in group B per patient-year) nor the time to a first peritoneal infection (median: 42 months vs 38 months) differed significantly between the study groups. In contrast, group B had a significantly higher incidence of catheter tunnel and exit-site infections (0.23 episodes vs 0.12 episodes per patient-year) and shorter time to a first infection episode (64 months vs 76 months, p = 0.004). The difference persisted in multivariate analysis (adjusted hazard ratio: 2.65; 95% confidence interval: 1.13 to 6.05; p = 0.013). We observed no differences between the study groups in the spectrum of causative organisms or in the outcomes of PD-related infections.

CONCLUSIONS

Poor glycemic control is a consistent predictor of subsequent risk of catheter tunnel and exit-site infection, but not of peritoneal infection, among diabetic patients starting PD therapy.

The effects of biocompatible compared with standard peritoneal dialysis solutions on peritonitis microbiology, treatment, and outcomes: the balANZ trial

BACKGROUND

A multicenter, multi-country randomized controlled trial (the balANZ study) recently reported that peritonitis rates significantly improved with the use of neutral-pH peritoneal dialysis (PD) solutions low in glucose degradation products ("biocompatible") compared with standard solutions. The present paper reports a secondary outcome analysis of the balANZ trial with respect to peritonitis microbiology, treatment, and outcomes.

METHODS

Adult incident PD patients with residual renal function were randomized to receive either biocompatible or conventional (control) PD solutions for 2 years.

RESULTS

The safety population analysis for peritonitis included 91 patients in each group. The unadjusted geometric mean peritonitis rates in those groups were 0.30 [95% confidence interval (CI): 0.22 to 0.41] episodes per patient-year for the biocompatible group and 0.49 (95% CI: 0.39 to 0.62) episodes per patient-year for the control group [incidence rate ratio (IRR): 0.61; 95% CI: 0.41 to 0.90; p = 0.01]. When specific causative organisms were examined, the rates of culture-negative, gram-positive, gram-negative, and polymicrobial peritonitis episodes were not significantly different between the biocompatible and control groups, although the biocompatible group did experience a significantly lower rate of non-pseudomonal gram-negative peritonitis (IRR: 0.41; 95% CI: 0.18 to 0.92; p = 0.03). Initial empiric antibiotic regimens were comparable between the groups. Biocompatible fluid use did not significantly reduce the risk of peritonitis-associated hospitalization (adjusted odds ratio: 0.80; 95% CI: 0.48 to 1.34), but did result in a shorter median duration of peritonitis-associated hospitalization (6 days vs 11 days, p = 0.05). Peritonitis severity was more likely to be rated as mild in the biocompatible group (37% vs 10%, p = 0.001). Overall peritonitis-associated technique failures and peritonitis-related deaths were comparable in the two groups.

CONCLUSIONS

Biocompatible PD fluid use was associated with a broad reduction in gram-positive, gram-negative, and culture-negative peritonitis that reached statistical significance for non-pseudomonal gram-negative organisms. Peritonitis hospitalization duration was shorter, and peritonitis severity was more commonly rated as mild in patients receiving biocompatible PD fluids, although other peritonitis outcomes were comparable between the groups.

Long-term efficacy of intermittent peritoneal dialysis using various doses

The objective of the present study was to investigate the long-term clinical efficacy of intermittent peritoneal dialysis (IPD) using various doses and to explore the most suitable dialysis dose and practice pattern for patients. A total of 52 inpatients/outpatients who had undergone IPD for more than 5 years were recruited and divided into three groups according to the dialysis dose: 4 liters in Group A, 6 liters in Group B and 8 liters in Group C. The dwell time was 4 h. All patients were fasted overnight. The dialysis adequacy, nutritional status, complication control, blood pressure and intra-abdominal infection were determined and observed among these patients. Barthel index (BI) and Hamilton Depression Scale (HAMD) were employed to measure the activities of daily living (ADL) and degree of depression, respectively. The dialysis adequacy and ultrafiltration volume in Group A were lower than those in Groups B and C, but the residual urine volume was larger than that in the latter two groups. In addition, there was a marked difference in the control of complications between Group A and Groups B and C. When compared to Groups A and B, the nutritional status in Group C was significantly decreased, the mean arterial pressure and intra-abdominal infection rates were dramatically increased, and the HAMD scores were also higher (P<0.05). No significant difference was noted in the BI. For patients undergoing long-term IPD, individualized dialysis dose may benefit the dialysis adequacy, nutritional status, control of complications, blood pressure, rate of intra-abdominal infection, ADL and depression.

Frequency and microbiology of peritonitis and exit-site infection among obese peritoneal dialysis patients

BACKGROUND

Data on obesity as a risk factor for peritonitis and catheter infections among peritoneal dialysis (PD) patients are limited. Furthermore, little is known about the microbiology of PD-related infections among patients with a high body mass index (BMI).

METHODS

Using a cohort that included all adult patients residing in the province of Manitoba who received PD during the period 1997 - 2007, we studied the relationship between BMI and PD-related infections. After categorizing patients into quartiles of BMI, a multivariate Cox regression model was used to determine the independent relationship between BMI and peritonitis or exit-site infection (ESI). We also studied whether increasing BMI was associated with a propensity to infections with particular organisms.

RESULTS

Among 990 PD patients, 938 (95%) had accurate BMI data available. Those 938 patients experienced 1338 peritonitis episodes and 1194 exit-site infections. In unadjusted analyses, patients in the highest BMI quartile (median: 33.5; interquartile range: 31.9 - 36.4) had an increased risk of peritonitis overall, and also an increased risk of peritonitis with gram-positive organisms and coagulase-negative Staphylococcus (CNS). After multivariate adjustment for age, sex, diabetes, cause of renal disease, Aboriginal race, PD modality, and S. aureus nasal carriage, the relationship between overall peritonitis risk and BMI disappeared, but the increased risk of CNS peritonitis among patients in the highest BMI quartile persisted (hazard ratio: 1.80; 95% confidence interval: 1.06 to 3.06; p = 0.03). There was no increased risk of ESI among patients in the highest BMI quartile on univariate analysis or after multivariate adjustment.

CONCLUSIONS

Among Canadian PD patients, obesity was not associated with an increased risk of peritonitis overall, but may be associated with a higher risk of CNS peritonitis.

Effects of climatic region on peritonitis risk, microbiology, treatment, and outcomes: a multicenter registry study

BACKGROUND

The impact of climatic variations on peritoneal dialysis (PD)-related peritonitis has not been studied in detail. The aim of the current study was to determine whether various climatic zones influenced the probability of occurrence or the clinical outcomes of peritonitis.

METHODS

Using ANZDATA registry data, the study included all Australian patients receiving PD between 1 October 2003 and 31 December 2008. Climatic regions were defined according to the Köppen classification.

RESULTS

The overall peritonitis rate was 0.59 episodes per patient-year. Most of the patients lived in Temperate regions (65%), with others residing in Subtropical (26%), Tropical (6%), and Other climatic regions (Desert, 0.6%; Grassland, 2.3%). Compared with patients in Temperate regions, those in Tropical regions demonstrated significantly higher overall peritonitis rates and a shorter time to a first peritonitis episode [adjusted hazard ratio: 1.15; 95% confidence interval (CI): 1.01 to 1.31]. Culture-negative peritonitis was significantly less likely in Tropical regions [adjusted odds ratio (OR): 0.42; 95% CI: 0.25 to 0.73]; its occurrence in Subtropical and Other regions was comparable to that in Temperate regions. Fungal peritonitis was independently associated with Tropical regions (OR: 2.18; 95% CI: 1.22 to 3.90) and Other regions (OR: 3.46; 95% CI: 1.73 to 6.91), where rates of antifungal prophylaxis were also lower. Outcomes after first peritonitis episodes were comparable in all groups.

CONCLUSIONS

Tropical regions were associated with a higher overall peritonitis rate (including fungal peritonitis) and a shorter time to a first peritonitis episode. Augmented peritonitis prophylactic measures such as antifungal therapy and exit-site care should be considered in PD patients residing in Tropical climates.

The effects of living distantly from peritoneal dialysis units on peritonitis risk, microbiology, treatment and outcomes: a multi-centre registry study

Background

The aim of the study was to determine whether distance between residence and peritoneal dialysis (PD) unit influenced peritonitis occurrence, microbiology, treatment and outcomes.

Methods

The study included all patients receiving PD between 1/10/2003 and 31/12/2008, using ANZDATA Registry data.

Results

365 (6%) patients lived ≥100 km from their nearest PD unit (distant group), while 6183 (94%) lived <100 km (local group). Median time to first peritonitis in distant patients (1.34 years, 95% CI 1.07-1.61) was significantly shorter than in local patients (1.68 years, 95% CI 1.59-1.77, p = 0.001), whilst overall peritonitis rates were higher in distant patients (incidence rate ratio 1.32, 95% CI 1.20-1.46). Living ≥100 km away from a PD unit was independently associated with a higher risk of S. aureus peritonitis (adjusted odds ratio [OR] 1.64, 95% CI 1.09-2.47). Distant patients with first peritonitis episodes were less likely to be hospitalised (64% vs 73%, p = 0.008) and receive antifungal prophylaxis (4% vs 10%, p = 0.01), but more likely to receive vancomycin-based antibiotic regimens (52% vs 42%, p < 0.001). Using multivariable logistic regression analysis of peritonitis outcomes, distant patients were more likely to be cured with antibiotics alone (OR 1.55, 95% CI 1.03-2.24). All other outcomes were comparable between the two groups.

Conclusions

Living ≥100 km away from a PD unit was associated with increased risk of S. aureus peritonitis, modified approaches to peritonitis treatment and peritonitis outcomes that were comparable to, or better than patients living closer to a PD unit. Staphylococcal decolonisation should receive particular consideration in remote living patients.

Recent peritonitis associates with mortality among patients treated with peritoneal dialysis

Peritonitis is a major complication of peritoneal dialysis, but the relationship between peritonitis and mortality among these patients is not well understood. In this case-crossover study, we included the 1316 patients who received peritoneal dialysis in Australia and New Zealand from May 2004 through December 2009 and either died on peritoneal dialysis or within 30 days of transfer to hemodialysis. Each patient served as his or her own control. The mean age was 70 years, and the mean time receiving peritoneal dialysis was 3 years. In total, there were 1446 reported episodes of peritonitis with 27% of patients having ≥ 2 episodes. Compared with the rest of the year, there were significantly increased odds of peritonitis during the 120 days before death, although the magnitude of this association was much greater during the 30 days before death. Compared with a 30-day window 6 months before death, the odds for peritonitis was six-fold higher during the 30 days immediately before death (odds ratio, 6.2; 95% confidence interval, 4.4-8.7). In conclusion, peritonitis significantly associates with mortality in peritoneal dialysis patients. The increased odds extend up to 120 days after an episode of peritonitis but the magnitude is greater during the initial 30 days.

Temporal trends in peritonitis rates, microbiology and outcomes: the major clinical complication of peritoneal dialysis

Peritonitis remains a common complication of peritoneal dialysis (PD). The aim of this study was to analyze, in a PD center, long-term temporal trends in peritonitis rates, microbiology and outcomes. We treated 588 cases of peritonitis that occurred during 11,833.6 months at risk. Y-set and twin-bag disconnecting systems were introduced in 1990, mupirocin at the exit site in 2000 and fluconazole prophylaxis in 2005. Vancomycin and ceftazidime were the empiric protocol. Global and 5-year cohort rates were expressed as episodes/patient-year (ep/p-y). A global peritonitis rate reduction was found from 1.02 to 0.47 ep/p-y (p = 0.008). Poisson analyses performed in each of the subgroups of Gram-positive and Gram-negative peritonitis revealed no significant changes over time. No case of vancomycin resistance was identified. There was a downward trend in peritonitis-related hospitalization over time to 0.11 ep/p-y (p ≤ 0.001). Trend analysis showed a favorable, but changing evolution, highlighting the importance of accurate longitudinal PD center registry data and quality control.

Weekend compared with weekday presentations of peritoneal dialysis-associated peritonitis

OBJECTIVE

Management of peritoneal dialysis (PD)-associated peritonitis requires timely intervention by experienced staff, which may not be uniformly available throughout the week. The aim of the present study was to examine the effects of weekend compared with weekday presentation on peritonitis outcomes.

METHODS

The study, which used data from the Australia and New Zealand Dialysis and Transplant Registry, included all Australian patients receiving PD between 1 October 2003 and 31 December 2008. The independent predictors of weekend presentation and subsequent peritonitis outcomes were assessed by multivariate logistic regression.

RESULTS

Peritonitis presentation rates were significantly lower on Saturdays [0.46 episodes per year; 95% confidence interval (CI): 0.42 to 0.49 episodes per year] and on Sundays (0.43 episodes per year; 95% CI: 0.40 to 0.47 episodes per year) than all other weekdays; they peaked on Mondays (0.76 episodes per year; 95% CI: 0.72 to 0.81 episodes per year). Weekend presentation with a first episode of peritonitis was independently associated with lower body mass index and residence less than 100 km away from the nearest PD unit. Patients presenting with peritonitis on the weekend were significantly more likely to be hospitalized [adjusted odds ratio (OR): 2.32; 95% CI: 1.85 to 2.90], although microbial profiles and empiric antimicrobial treatments were comparable between the weekend and weekday groups. Antimicrobial cure rates were also comparable (79% vs 79%, p = 0.9), with the exception of cure rates for culture-negative peritonitis, which were lower on the weekend (80% vs 88%, p = 0.047). Antifungal prophylaxis was less likely to be co-prescribed for first peritonitis episodes presenting on weekdays (OR: 0.68; 95% CI: 0.05 to 0.89).

CONCLUSIONS

Patients on PD are less likely to present with peritonitis on the weekend. Nevertheless, the microbiology, treatment, and outcomes of weekend and weekday PD peritonitis presentations are remarkably similar. Exceptions include the associations of weekend presentation with a higher hospitalization rate and a lower cure rate in culture-negative infection.

Microbiology of peritonitis in peritoneal dialysis patients with multiple episodes

BACKGROUND

Peritoneal dialysis (PD)-associated peritonitis clusters within patients. Patient factors contribute to peritonitis risk, but there is also entrapment of organisms within the biofilm that forms on PD catheters. It is hypothesized that this biofilm may prevent complete eradication of organisms, predisposing to multiple infections with the same organism.

METHODS

Using data collected in the Canadian multicenter Baxter POET (Peritonitis, Organism, Exit sites, Tunnel infections) database from 1996 to 2005, we studied incident PD patients with 2 or more peritonitis episodes. We determined the proportion of patients with 2 or more episodes caused by the same organism. In addition, using a multivariate logistic regression model, we tested whether prior peritonitis with a given organism predicted the occurrence of a subsequent episode with the same organism.

RESULTS

During their time on PD, 558 patients experienced 2 or more peritonitis episodes. Of those 558 patients, 181 (32%) had at least 2 episodes with the same organism. The organism most commonly causing repeat infection was coagulase-negative Staphylococcus (CNS), accounting for 65.7% of cases. Compared with peritonitis caused by other organisms, a first CNS peritonitis episode was associated with an increased risk of subsequent CNS peritonitis within 1 year (odds ratio: 2.1; 95% confidence interval: 1.5 to 2.8; p < 0.001). Among patients with repeat CNS peritonitis, 48% of repeat episodes occurred within 6 months of the earlier episode.

CONCLUSIONS

In contrast to previous data, we did not find a high proportion of patients with multiple peritonitis episodes caused by the same organism. Coagulase-negative Staphylococcus was the organism most likely to cause peritonitis more than once in a given patient, and a prior CNS peritonitis was associated with an increased risk of CNS peritonitis within the subsequent year.

Infectious complications in dialysis--epidemiology and outcomes

This Review focuses on the changing epidemiology of infections among patients with end-stage renal disease who are undergoing dialysis. In particular, bloodstream infections related to vascular access in patients undergoing hemodialysis, and peritonitis in patients undergoing peritoneal dialysis, are highlighted. Gram-positive (staphylococcal and enterococcal) bloodstream infections and Gram-negative peritonitis (especially extended-spectrum β-lactamase-producing organisms) contribute substantially to excess health-care use owing to infection caused by dialysis access. Although the management of peritoneal-dialysis-related peritonitis has been hampered by a dearth of randomized, controlled studies, epidemiological data have provided useful information. To overcome the problem of differing methods used to monitor infections within various dialysis centers, uniform reporting systems for vascular-access-related infection and peritoneal-dialysis-related peritonitis, as recommended by the Centers for Disease Control and Prevention and the International Society for Peritoneal Dialysis, respectively, are discussed. Infections unrelated to the port of entry for dialysis are also examined, namely hepatitis and respiratory infection. To address the disease burden, we examine the infection-related mortality as well as the implications for subsequent cardiovascular mortality.

Seasonal variation in peritoneal dialysis-associated peritonitis: a multi-centre registry study

BACKGROUND

The role of seasonal variation in peritoneal dialysis (PD)-related peritonitis has been limited to a few small single-centre studies.

METHODS

Using all 6610 Australian patients receiving PD between 1 October 2003 and 31 December 2008, we evaluated the influence of seasons on peritonitis rates (Poisson regression) and outcomes (multivariable logistic regression).

RESULTS

The overall rate of peritonitis was 0.59 episodes per patient-year of treatment. Using winter as the reference season, the peritonitis incidence rate ratios (95% confidence interval) for summer, autumn and spring were 1.02 (0.95-1.09), 1.01 (0.94-1.08) and 0.99 (0.92-1.06), respectively. Significant seasonal variations were observed in the rates of peritonitis caused by coagulase-negative Staphylococci (spring and summer peaks), corynebacteria (winter peak) and Gram-negative organisms (summer and autumn peaks). There were trends to seasonal variations in fungal peritonitis (summer and autumn peaks) and pseudomonas peritonitis (summer peak). No significant seasonal variations were observed for other organisms. Peritonitis outcomes did not significantly vary according to season.

CONCLUSIONS

Seasonal variation has no appreciable influence on overall PD peritonitis rates or clinical outcomes. Nevertheless, significant seasonal variations were observed in the rates of peritonitis due to specific microorganisms, which may allow institutions to more precisely target infection control strategies prior to higher risk seasons.

Repeated peritoneal dialysis-associated peritonitis: a multicenter registry study

BACKGROUND

Determinants and outcomes of peritoneal dialysis (PD)-associated peritonitis occurring within 4 weeks of completion of therapy of a prior episode caused by the same (relapse) or different organism (recurrence) recently have been characterized. However, determinants and outcomes of peritonitis occurring more than 4 weeks after treatment of a prior episode caused by the same (repeated) or different organism (nonrepeated) are poorly understood.

STUDY DESIGN

Observational cohort study using Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) data.

SETTING & PARTICIPANTS

All Australian PD patients between October 1, 2003, and December 31, 2007, with first episodes of repeated or nonrepeated peritonitis.

PREDICTORS

Repeated versus nonrepeated peritonitis, according to International Society of PD (ISPD) criteria.

OUTCOMES & MEASUREMENTS

Relapse, hospitalization, catheter removal, hemodialysis transfer, and death.

RESULTS

After a peritonitis episode, the probability that a subsequent episode represented repeated rather than nonrepeated peritonitis was highest in the second month (41%), then progressively decreased to a stable level of 14% from 6 months onward. When first episodes of repeated (n = 245) or nonrepeated peritonitis (n = 824) were analyzed, repeated peritonitis was predicted independently by a shorter elapsed time from the prior episode (adjusted OR per day elapsed, 0.91; 95% CI, 0.88-0.94). Staphylococcus aureus and coagulase-negative staphylococcus were isolated more frequently in repeated peritonitis, whereas Gram-negative, streptococcal, and fungal organisms were recovered more frequently in nonrepeated peritonitis. Using multivariate logistic regression, repeated peritonitis was associated independently with higher relapse (OR, 5.41; 95% CI, 3.72-7.89) and lower hospitalization rates (OR, 0.63; 95% CI, 0.46-0.85), but catheter removal, hemodialysis transfer, and death rates similar to nonrepeated peritonitis.

LIMITATIONS

Limited covariate adjustment. Residual confounding and coding bias could not be excluded.

CONCLUSIONS

Repeated and nonrepeated peritonitis episodes are caused by different spectra of micro-organisms and have different outcomes. Study findings suggest that the ISPD definition for repeated peritonitis should be limited to 6 months.

Microbiology and outcomes of peritonitis in Australian peritoneal dialysis patients

We analyzed data from the Australia and New Zealand Dialysis and Transplant Registry for 1 October 2003 to 31 December 2008 with the aim of describing the nature of peritonitis, therapies, and outcomes in patients on peritoneal dialysis (PD) in Australia. At least 1 episode of PD was observed in 6639 patients. The overall peritonitis rate was 0.60 episodes per patient-year (95% confidence interval: 0.59 to 0.62 episodes), with 6229 peritonitis episodes occurring in 3136 patients. Of those episodes, 13% were culture-negative, and 11% were polymicrobial. Gram-positive organisms were isolated in 53.4% of single-organism peritonitis episodes, and gram-negative organisms, in 23.6%. Mycobacterial and fungal peritonitis episodes were rare. Initial antibiotic therapy for most peritonitis episodes used 2 agents (most commonly vancomycin and an aminoglycoside); in 77.2% of episodes, therapy was subsequently changed to a single agent. Tenckhoff catheter removal was required in 20.4% of cases at a median of 6 days, and catheter removal was more common in fungal, mycobacterial, and anaerobic infections, with a median time to removal of 4 - 5 days. Peritonitis was the cause of death in 2.6% of patients. Transfer to hemodialysis and hospitalization were frequent outcomes of peritonitis. There was no relationship between center size and peritonitis rate. The peritonitis rate in Australia between 2003 and 2008 was higher than that reported in many other countries, with a particularly higher rate of gram-negative peritonitis.

Relapsing and recurrent peritoneal dialysis-associated peritonitis: a multicenter registry study

BACKGROUND

The causes, predictors, treatment, and outcomes of relapsed and recurrent peritoneal dialysis (PD)-associated peritonitis are poorly understood.

STUDY DESIGN

Observational cohort study using Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry data.

SETTING & PARTICIPANTS

All Australian PD patients between October 1, 2003, and December 31, 2007, with first episodes of peritonitis.

PREDICTORS

Demographic, clinical, and facility variables and type of peritonitis; relapse (same organism or culture-negative episode occurring within 4 weeks of completion of therapy of a prior episode or 5 weeks if vancomycin used); recurrence (different organism occurring within 4 weeks of completion of therapy of a prior episode or 5 weeks if vancomycin used); control (first peritonitis episode without relapse or recurrence).

OUTCOMES & MEASUREMENTS

Hospitalization, catheter removal, hemodialysis therapy transfer, death.

RESULTS

Of 6,024 PD patients studied, first episodes of relapsed, recurrent, and control peritonitis occurred in 356, 165, and 2,021 patients, respectively. Coagulase-negative staphylococci and Staphylococcus aureus accounted for 48% of relapsing peritonitis (adjusted OR, 1.26 [95% CI, 0.94-1.70] and 1.54 [95% CI, 1.08-2.19], respectively), but were much less likely to be isolated in recurrent peritonitis. Recurrent peritonitis was associated more frequently with fungi (13%; OR, 2.16; 95% CI, 1.12-4.17). The empirical antimicrobial approaches to relapsing and recurrent peritonitis were similar and their subsequent clinical outcomes were comparable. Compared with uncomplicated peritonitis, relapsed and recurrent peritonitis were associated with higher rates of catheter removal (22% vs 30% vs 37%, respectively; P < 0.001) and permanent hemodialysis therapy transfer (20% vs 25% vs 32%; P < 0.001), but similar rates of hospitalization (73% vs 70% vs 70%) and death (2.8% vs 2.0% vs 1.2%).

LIMITATIONS

Limited covariate adjustment. Residual confounding and coding bias could not be excluded.

CONCLUSIONS

Relapsed and recurrent peritonitis are caused by different spectra of micro-organisms, but are not readily clinically distinguishable at presentation. Empirical treatment with broad-spectrum antibiotics and subsequent adjustment according to antimicrobial susceptibilities results in similar clinical outcomes, albeit with appreciably higher rates of catheter removal and hemodialysis therapy transfer than for uncomplicated peritonitis.

Repeat peritonitis in peritoneal dialysis: retrospective review of 181 consecutive cases

BACKGROUND AND OBJECTIVES

The clinical behavior of repeat-peritonitis episodes, defined as peritonitis with the same organism occurring more than 4 weeks after completion of therapy for a prior episode, is poorly understood.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We compared outcomes of 181 episodes of repeat peritonitis from 1995 to 2009 (Repeat Group) with 91 episodes of relapsing peritonitis (Relapsing Group) and 125 episodes of peritonitis preceded 4 weeks or longer by another episode with a different organism (Control Group).

RESULTS

In Repeat Group, 24% were due to Staphylococcus aureus, as compared with 5.5% in Relapsing Group and 15% in Control Group. The majority of the organisms causing relapsing peritonitis were Gram negative (62%), whereas the majority of that in Repeat Group were Gram positive (56%). Repeat Group had a lower complete-cure rate (70.7% versus 54.9%) than Relapsing Group, but rates of primary response, catheter removal, and mortality were similar. Repeat Group had a higher primary response rate (89.0% versus 73.6%) and a lower rate of catheter removal (6.1% versus 15.2%) than Control Group, whereas the complete-cure rate and mortality were similar. Repeat Group had a higher risk of developing relapsing (14.3% versus 2.2%) and repeat peritonitis (26.1% versus 5.4%) than Control Group, whereas the risk of recurrent peritonitis was similar.

CONCLUSIONS

Repeat peritonitis is a distinct clinical entity. Although repeat-peritonitis episodes generally have a satisfactory response to antibiotic, they have a substantial risk of developing further relapsing or repeat peritonitis.