Predictors and outcomes of fungal peritonitis in peritoneal dialysis patients

A case of recurrent peritoneal dialysis-related peritonitis caused by Stenotrophomonas maltophilia during ongoing antibiotic treatment for Enterococcus faecalis-induced peritonitis

Recurrent peritonitis is a serious complication of peritoneal dialysis (PD), which could result in PD withdrawal and mortality. However, cases of recurrent peritonitis occurring during ongoing antimicrobial therapy are rarely reported. Herein, we present a 71-year-old man who experienced initial peritonitis due to Enterococcus faecalis. Despite effective antimicrobial therapy, he developed recurrent peritonitis while on antimicrobial therapy. PD fluid culture analysis yielded Stenotrophomonas maltophilia (S. maltophilia). He was treated with multiple antimicrobials, and the peritoneal catheter was removed. To the best of our knowledge, this is the first case of recurrent peritonitis caused by S. maltophilia, which was developed during antimicrobial treatment. Our report findings suggest the importance of considering S. maltophilia infection in an atypical case of very early recurrent peritonitis.

Unusual and complicated peritonitis: Your questions answered

Effective treatment of infections is a growing challenge owing to antimicrobial resistance. Peritoneal dialysis (PD) patients experience more frequent hospitalisations than the general population and have greater exposure to antibiotics, making them particularly vulnerable to this threat. Over the last decade, we have noted a surge in cases of complicated peritoneal dialysis-associated peritonitis (PD peritonitis) caused by antimicrobial-resistant organisms, including extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase-producing Enterobacterales, Pseudomonas aeruginosa and fungi. Practitioners must be alert to these organisms, seek early recognition of these resistance patterns and make timely adjustments in order to avoid delay in treatment that may increase risk of PD catheter removal and technique failure. We present a case of successful treatment of ESBL peritonitis, highlight its challenges, while providing guidance on management of other unusual and complicated PD peritonitis.

The efficacy of fluconazole for anti-fungal prophylaxis in peritoneal dialysis patients: A systematic review and meta-analysis

INTRODUCTION AND OBJECTIVES

The efficacy of fluconazole as a prophylactic strategy in patients with chronic kidney disease (CKD) on peritoneal dialysis (PD) with prior antibiotic exposure is controversial in the current literature. This study aimed to compare a strategy of fluconazole prophylaxis versus no-prophylaxis for patients in PD on antibiotics for previous episodes of peritonitis.

MATERIALS AND METHODS

We performed a systematic review and meta-analysis of observational studies and randomized controlled trials (RCTs) comparing fluconazole prophylaxis with no prophylaxis for PD-related peritonitis. The search was conducted on PubMed, EMBASE, and Cochrane Central in January 23, 2023. The outcome of interest was the occurrence of fungal peritonitis (FP).

RESULTS

We included six studies (1 RCT, 5 observational) with 4515 occurrences of peritonitis, of which 1098 (24.8%) received fluconazole prophylaxis in variable doses, whereas 3417 (75.6%) did not receive prophylaxis during peritonitis episodes. Overall, fluconazole prophylaxis was associated with a lower incidence of FP (OR 0.22; 95% CI 0.12-0.41; p<0.001; I2=0%). Subgroup analysis of studies that administered daily doses of fluconazole also demonstrated a reduced incidence of FP in patients who received antifungal prophylaxis (OR 0.31; CI 0.14-0.69; p=0.004; I2=0%).

CONCLUSIONS

In this meta-analysis of 4515 episodes of PD-related peritonitis, prophylaxis with fluconazole significantly reduced episodes of FP as compared with no antifungal prophylaxis.

Protection against lethal sepsis following immunization with Candida species varies by isolate and inversely correlates with bone marrow tissue damage

Protection against lethal Candida albicans (Ca)/Staphylococcus aureus (Sa) intra-abdominal infection (IAI)-mediated sepsis can be achieved by a novel form of trained innate immunity (TII) involving Gr-1+ myeloid-derived suppressor cells (MDSCs) that are induced by inoculation (immunization) with low virulence Candida species [i.e., Candida dubliniensis (Cd)] that infiltrate the bone marrow (BM). In contrast, more virulent Candida species (i.e., C. albicans), even at sub-lethal inocula, fail to induce similar levels of protection. The purpose of the present study was to test the hypothesis that the level of TII-mediated protection induced by Ca strains inversely correlates with damage in the BM as a reflection of virulence. Mice were immunized by intraperitoneal inoculation with several parental and mutant strains of C. albicans deficient in virulence factors (hyphal formation and candidalysin production), followed by an intraperitoneal Ca/Sa challenge 14 d later and monitored for sepsis and mortality. Whole femur bones were collected 24 h and 13 d after immunization and assessed for BM tissue/cellular damage via ferroptosis and histology. While immunization with standard but not sub-lethal inocula of most wild-type C. albicans strains resulted in considerable mortality, protection against lethal Ca/Sa IAI challenge varied by strain was usually less than that for C. dubliniensis, with no differences observed between parental and corresponding mutants. Finally, levels of protection afforded by the Ca strains were inversely correlated with BM tissue damage (R 2 = -0.773). TII-mediated protection against lethal Ca/Sa sepsis induced by Candida strain immunization inversely correlates with BM tissue/cellular damage as a reflection of localized virulence.

Peritoneal Dialysis in Critically Ill Patients: Time for a Critical Reevaluation?

Peritoneal dialysis (PD) as an AKI treatment in adults was widely accepted in critical care settings well into the 1980s. The advent of extracorporeal continuous KRT led to widespread decline in the use of PD for AKI across high-income countries. The lack of familiarity and comfort with the use of PD in critical care settings has also led to lack of use even among those receiving maintenance PD. Many critical care units reflexively convert patients receiving maintenance PD to alternative dialysis therapies at admission. Renewed interest in the use of PD for AKI therapy has emerged due to its increasing use in low- and middle-income countries. In high-income countries, the coronavirus disease 2019 (COVID-19) pandemic, saw PD for AKI used early on, where many critical care units were in crisis and relied on PD use when resources for other AKI therapy modalities were limited. In this review, we highlight advantages and disadvantages of PD in critical care settings and indications and contraindications for its use. We provide an overview of literature to support both PD treatment during AKI and its continuation as a maintenance therapy during critical illness. For AKI therapy, we further discuss establishment of PD access, PD prescription management, and complication monitoring and treatment. Finally, we discuss expansion in the use of PD for AKI therapy extending beyond its role during times of resource constraints.

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.

Novel Aspects of the Immune Response Involved in the Peritoneal Damage in Chronic Kidney Disease Patients under Dialysis

Chronic kidney disease (CKD) incidence is growing worldwide, with a significant percentage of CKD patients reaching end-stage renal disease (ESRD) and requiring kidney replacement therapies (KRT). Peritoneal dialysis (PD) is a convenient KRT presenting benefices as home therapy. In PD patients, the peritoneum is chronically exposed to PD fluids containing supraphysiologic concentrations of glucose or other osmotic agents, leading to the activation of cellular and molecular processes of damage, including inflammation and fibrosis. Importantly, peritonitis episodes enhance peritoneum inflammation status and accelerate peritoneal injury. Here, we review the role of immune cells in the damage of the peritoneal membrane (PM) by repeated exposure to PD fluids during KRT as well as by bacterial or viral infections. We also discuss the anti-inflammatory properties of current clinical treatments of CKD patients in KRT and their potential effect on preserving PM integrity. Finally, given the current importance of coronavirus disease 2019 (COVID-19) disease, we also analyze here the implications of this disease in CKD and KRT.

Treatment and outcomes of peritonitis due to Rothia species in patients on peritoneal dialysis: A systematic review and multicentre registry analysis

Peritoneal dialysis (PD)-associated peritonitis remains a severe complication of PD. Although peritonitis due to Rothia spp. is rare, the treatment recommendations and outcomes are uncertain. Our study aims to review (1) published literature on peritonitis caused by Rothia spp. and (2) reported cases of peritonitis due to Rothia spp. in patients on PD in Australia and New Zealand. A literature search of PubMed, Scopus, Embase and Google Scholar for articles published between January 1949 and February 2022 was conducted. To be eligible, articles had to describe antibiotic therapy and treatment outcomes in all PD patients for peritonitis caused by Rothia or Stomatococcus spp. Data from the Australia and New Zealand Dialysis and Transplant (ANZDATA) registry of PD patients who developed peritonitis due to Rothia spp. between July 2011 and May 2020 were also reviewed. A total of 12 articles and 28 episodes were identified from the literature search and ANZDATA registry analysis, respectively. Over 60% of the peritonitis cases due to Rothia spp. were from the Rothia mucilaginosa species (8/12 and 17/28, respectively), while Rothia dentocariosa was the second most commonly identified species in both the literature search and the ANZDATA registry analysis (4/12 and 5/28, respectively). A majority 8 (66.7%) of the articles in the literature search employed a combination antibiotic regimen, while the remaining 4 (33.3%) used a single antibiotic regimen. In contrast, most of the episodes, 22 (78.6%) described in the ANZDATA registry analysis, employed a single antibiotic regimen, and only 6 (21.4%) episodes were treated with a combination antibiotic regimen. The duration of antibiotic therapy ranged from 2 to 3 weeks in the literature search, and 1 to 3 weeks in the ANZDATA registry. While no deaths within 30 days of developing peritonitis were reported, catheter removal was reported in three (25%) and two (7.1%) episodes in both the literature search and the ANZDATA registry analysis, respectively, of which the majority occurred in patients treated for ≤2 weeks. PD-associated peritonitis due to Rothia spp. is uncommon and associated with relatively good outcomes. Antibiotic treatment for 3 weeks is associated with better outcomes.

A case of Moesziomyces antarcticus peritonitis in a patient undergoing peritoneal dialysis

Background

Fungal peritonitis is a common and serious complication associated with peritoneal dialysis (PD), and it is often refractory to treatment.

Case presentation

A 70-year-old patient undergoing peritoneal dialysis was admitted to our hospital with fever and cloudy PD fluid. A diagnosis of yeast-like fungal peritonitis was made by examining the PD fluid. After starting intravenous caspofungin acetate, the PD catheter was removed. A fungal pathogen was isolated from the peritoneal fluid and identified as Cryptococcus sp. Based on the results of antifungal susceptibility testing, the treatment was changed to oral voriconazole and continued for 6 weeks. However, because of the discrepancy between the morphological findings and culture results, we performed genetic analysis, which uncovered Moesziomyces antarcticus. This patient was diagnosed with PD-related peritonitis caused by M. antarcticus and was successfully treated with voriconazole and removal of the PD catheter.

Conclusions

Reports of human infection by M. antarcticus are rare, and only two cases have been recognized. This may be the first case of infection detected in PD fluid.

Fungal Peritonitis Associated With Peritoneal Dialysis Due to Non-Albicans Candida: A Case Series

Fungal peritonitis secondary to non-albicans Candida is reported less frequently. There are uncertainties regarding the treatment of non-albicans Candida infection (i.e., preferred route or initial drug). The objective of this study is to determine the clinical characteristics and treatment used in cases of peritoneal dialysis associated fungal peritonitis secondary to non-albicans Candida. We report four cases with different clinical characteristics and different routes of administration of the antifungal drug, with no deaths. In all four patients, there were risk factors similar to those reported worldwide, without presenting the route of administration of the antifungal drug as a risk factor, suggesting that the mainstay of treatment is early initiation of the antifungal drug and early removal of the catheter.

Efficacy of Candida dubliniensis and Fungal β-Glucans in Inducing Trained Innate Immune Protection Against Inducers of Sepsis

Fungal-bacterial intra-abdominal infections (IAI) can lead to sepsis with significant morbidity and mortality. We have established a murine model of Candida albicans (Ca) and Staphylococcus aureus (Sa) IAI that results in acute lethal sepsis. Prior intraperitoneal or intravenous inoculation with low virulence Candida dubliniensis (Cd) confers high level protection against lethal Ca/Sa IAI and sepsis. Protection via Cd immunization is associated with decreased pro-inflammatory cytokines and mediated by Gr-1⁺ putative myeloid-derived suppressor cells (MDSCs) representing a novel form of trained innate immunity (TII). The objective of these studies was to determine the extent of Cd-mediated TII against sepsis of broad origin and explore the potential of fungal cell wall components as abiotic immunogen alternatives to induce TII, including zymosan depleted of TLR2 activity (d-zymosan), or purified preparations of β-glucan. Immunized mice were challenged 14 days post-immunization with a lethal array of live or abiotic inducers of sepsis, including Ca/Sa, Ca/Escherichia coli (Ca/Ec), LPS or untreated zymosan. Results showed that live Cd immunization was protective against sepsis induced by Ca/Ec and zymosan, but not LPS. Similar to protection against Ca/Sa, survival was dependent on Gr-1+ cells with no role for macrophages. Among the fungal cell wall compounds as immunogens, immunization with d-zymosan and an alkali-treated form of β-glucan also resulted in significant protection against sepsis induced by Ca/Sa or Ca/Ec, but not LPS sepsis. Again, there was a strong dependence on Gr-1+ cells for protection with one exception, an added role for macrophages in the case of protection induced by alkali-treated β-glucan. Overall, these results demonstrate that immunization with Cd as well as abiotic fungal cell components are capable of Gr-1+ cell-mediated trained innate immune protection against sepsis of broad microbial origin. In addition, abiotic β-glucans represent potential alternatives to live Cd for protection against lethal polymicrobial sepsis.

Predictors and outcomes of peritoneal dialysis-related infections due to filamentous molds (MycoPDICS)

Introduction

We sought to evaluate the predictors and outcomes of mold peritonitis in patients with peritoneal dialysis (PD).

Methods

This cohort study included PD patients from the MycoPDICS database who had fungal peritonitis between July 2015-June 2020. Patient outcomes were analyzed by Kaplan Meier curves and the Log-rank test. Multivariable Cox proportional hazards model regression was used to estimating associations between fungal types and patients’ outcomes.

Results

The study included 304 fungal peritonitis episodes (yeasts n = 129, hyaline molds n = 122, non-hyaline molds n = 44, and mixed fungi n = 9) in 303 patients. Fungal infections were common during the wet season (p <0.001). Mold peritonitis was significantly more frequent in patients with higher hemoglobin levels, presentations with catheter problems, and positive galactomannan (a fungal cell wall component) tests. Patient survival rates were lowest for non-hyaline mold peritonitis. A higher hazard of death was significantly associated with leaving the catheter in-situ (adjusted hazard ratio [HR] = 6.15, 95%confidence interval [CI]: 2.86–13.23) or delaying catheter removal after the diagnosis of fungal peritonitis (HR = 1.56, 95%CI: 1.00–2.44), as well as not receiving antifungal treatment (HR = 2.23, 95%CI: 1.25–4.01) or receiving it for less than 2 weeks (HR = 2.13, 95%CI: 1.33–3.43). Each additional day of antifungal therapy beyond the minimum 14-day duration was associated with a 2% lower risk of death (HR = 0.98, 95%CI: 0.95–0.999).

Conclusion

Non-hyaline-mold peritonitis had worse survival. Longer duration and higher daily dosage of antifungal treatment were associated with better survival. Deviations from the 2016 ISPD Peritonitis Guideline recommendations concerning treatment duration and catheter removal timing were independently associated with higher mortality.

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.

COVID 19 Pneumonia and a Rare Form of Fungal Peritonitis in a Patient Survivor on Peritoneal Dialysis

Peritoneal dialysis (PD) related peritonitis is usually caused by bacteria, but viruses and fungi could also affect the peritoneal membrane and cause cloudy effluent with negative bacterial cultures. We present a case of a PD patient who survived fungal peritonitis caused by Geotrichum klebahnii (March 2015) and COVID-19 pneumonia (April 2021) with peritonitis probably caused by the SARS-CoV-2 virus. The fungal peritonitis followed one episode of exit-site infection and two episodes of bacterial peritonitis treated with a wide-spectrum antibiotic. The patient's PD catheter was removed immediately upon the diagnosis of fungal peritonitis, and an antifungal treatment was continued for 3 weeks after catheter removal. The new peritoneal catheter was reinserted 8 weeks after complete resolution of peritonitis, and the patient continued treatment with PD. The patient developed severe Covid-19 pneumonia with a sudden appearance of cloudy peritoneal effluent. There was no bacterial or fungal growth on the effluent culture. A PCR test for SARS-CoV-2 in peritoneal effluent was not performed. The peritoneal effluent became transparent with the resolution of the severe symptoms of Covid-19 pneumonia.

The effect of radiological imaging on treatment delay and hospitalisation in patients with peritoneal dialysis-related peritonitis: A secondary analysis of the PROMPT study

BACKGROUND

In peritoneal dialysis-related peritonitis (peritonitis), delayed antibiotic therapy is associated with adverse outcomes. Identifying barriers to timely treatment may improve outcomes.

AIM

To determine the impact of radiological investigations on treatment delay and predictors of hospitalisation and length of stay (LOS).

METHODS

Retrospective review of patients with presumed peritonitis in Western Australia.

RESULTS

In 153 episodes of peritonitis, 79 (51.6%) resulted in admission with a median LOS of 3 days (Q1, Q3: 1, 6). In a multivariable model, significant predictors of admission were abnormal exit-site (odds ration (OR) 5.7; 95% confidence interval (CI): 1.4, 23.6; p = 0.02), failure to detect a cloudy bag (OR 11.9; 95%CI: 3.2, 44.7; p < 0.001), female sex (OR 3.3; 95% CI: 1.4, 9.7; p = 0.027), radiological imaging within 24 h (OR 8.8; 95% CI: 2.2, 34.8; p = 0.002) and contact with ambulant care facility (OR 0.32, 95% CI: 0.11, 0.98; p = 0.04). Imaging within 24 h of presentation occurred in 41 (27%) episodes of peritonitis, mostly plain X-rays (91%), of which 83% were clinically irrelevant. Imaging performed within 24 h of presentation increased the median time to antibiotic treatment (2.9 h (Q1, Q3: 1.6, 6.4) vs 2.0 h (Q1, Q3: 1, 3.8; p = 0.046)). Imaging performed prior to administering antibiotics significantly increased the median time to treatment (4.7 h (Q1, Q3: 2.9, 25) vs 1.5 h (Q1, Q3: 0.75, 2.5; p < 0.001)) in those where imaging followed antibiotic treatment.

CONCLUSIONS

Half of all presentations with peritonitis result in hospital admission. Radiological imaging was associated with an increased risk of hospitalisation, potentially contributes to treatment delay, and was mostly clinically unnecessary. When required, imaging should follow antibiotic therapy.

Continuous Ambulatory Peritoneal Dialysis Peritonitis Guidelines - Consensus Statement of Peritoneal Dialysis Society of India - 2020

Continuous ambulatory peritoneal dialysis (CAPD) related peritonitis is a major cause of technique failure, morbidity, and mortality in patients on CAPD. Its prevention and management is key to success of CAPD program. Due to variability in practice, microbiological trends and sensitivity towards antibiotics, there is a need for customized guidelines for management of CAPD related peritonitis (CAPDRP) in India. With this need, Peritoneal Dialysis Society of India (PDSI) organized a structured meeting to discuss various aspects of management of CAPDRP and formulated a consensus agreement which will help in management of patients with CAPDRP.

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.

Two decades of analysis of peritonitis in peritoneal dialysis in Andalusia: Epidemiological, clinical, microbiological and progression aspects

BACKGROUND

This study focuses on the main complication associated with peritoneal dialysis, peritonitis. Its relevance derives from its high morbidity, the negative effect it has on the peritoneum as a dialysis membrane and its financial cost.

METHODS

Analytical, non-interventional, observational cohort study, whose main objective is the analysis of peritonitis in patients on peritoneal dialysis in Andalusia from 1 January 1999 to 31 December 2017, with a total of 2904 peritonitis cases. The database used is the Andalusian Autonomous Transplant Coordination Information System (SICATA).

OBJECTIVES

To ascertain how the rate of peritonitis is evolving in our community, analyse descriptive data pertaining to patients and peritonitis, ascertain the course of these infectious complications and analyse the factors that influence these cases of peritonitis and their outcomes: germ, hospitalisation and date.

RESULTS

The rate of peritonitis decreased progressively during the study period, from 0.7 peritonitis per patient in 1999 to 0.33 at the end of the period. Most infections were treated on an outpatient basis (72.5%). The most common germs were Gram-positive (55.9%), including coagulase-negative staphylococci (28.1%). Most cases of peritonitis progressed to healing (77.8%). The factors that significantly influence the need for hospitalisation and peritonitis progression were the causative germ and associated exit site infection.

CONCLUSIONS

In our population, the rate of peritonitis decreased progressively during the study period, meeting guideline recommendations.

Mechanisms of Peritoneal Fibrosis: Focus on Immune Cells-Peritoneal Stroma Interactions

Peritoneal fibrosis is characterized by abnormal production of extracellular matrix proteins leading to progressive thickening of the submesothelial compact zone of the peritoneal membrane. This process may be caused by a number of insults including pathological conditions linked to clinical practice, such as peritoneal dialysis, abdominal surgery, hemoperitoneum, and infectious peritonitis. All these events may cause acute/chronic inflammation and injury to the peritoneal membrane, which undergoes progressive fibrosis, angiogenesis, and vasculopathy. Among the cellular processes implicated in these peritoneal alterations is the generation of myofibroblasts from mesothelial cells and other cellular sources that are central in the induction of fibrosis and in the subsequent functional deterioration of the peritoneal membrane. Myofibroblast generation and activity is actually integrated in a complex network of extracellular signals generated by the various cellular types, including leukocytes, stably residing or recirculating along the peritoneal membrane. Here, the main extracellular factors and the cellular players are described with emphasis on the cross-talk between immune system and cells of the peritoneal stroma. The understanding of cellular and molecular mechanisms underlying fibrosis of the peritoneal membrane has both a basic and a translational relevance, since it may be useful for setup of therapies aimed at counteracting the deterioration as well as restoring the homeostasis of the peritoneal membrane.

Multicentre registry data analysis comparing outcomes of culture-negative peritonitis and different subtypes of culture-positive peritonitis in peritoneal dialysis patients

BACKGROUND

The outcomes of culture-negative peritonitis in peritoneal dialysis (PD) patients have been reported to be superior to those of culture-positive peritonitis. The current study aimed to examine whether this observation also applied to different subtypes of culture-positive peritonitis.

METHODS

This multicentre registry study included all episodes of peritonitis in adult PD patients in Australia between 2004 and 2014. The primary outcome was medical cure. Secondary outcomes were catheter removal, hemodialysis transfer, relapsing/recurrent peritonitis and peritonitis-related death. These outcomes were analyzed using mixed effects logistic regression.

RESULTS

Overall, 11,122 episodes of peritonitis occurring in 5367 patients were included. A total of 1760 (16%) episodes were culture-negative, of which 77% were medically cured. Compared with culture-negative peritonitis, the odds of medical cure were lower in peritonitis caused by Staphylococcus aureus (adjusted odds ratio (OR) 0.62, 95% confidence interval (CI) 0.52-0.73), Pseudomonas species (OR 0.20, 95% CI 0.16-0.26), other gram-negative organisms (OR 0.48, 95% CI 0.41-0.56), polymicrobial organisms (OR 0.30, 95% CI 0.25-0.35), fungi (OR 0.02, 95% CI 0.01-0.03), and other organisms (OR 0.61, 95% CI 0.49-0.76), while the odds were similar in other (non-staphylococcal) gram-positive organisms (OR 1.11, 95% CI 0.97-1.28). Similar results were observed for catheter removal and hemodialysis transfer. Compared with culture-negative peritonitis, peritonitis-related mortality was significantly higher in culture-positive peritonitis except that due to other gram-positive organisms. There was no difference in the odds of relapsing/recurrent peritonitis between culture-negative and culture-positive peritonitis.

CONCLUSION

Culture-negative peritonitis had superior outcomes compared to culture-positive peritonitis except for non-staphylococcal gram-positive peritonitis.

Longer antibiotic durations for treating peritoneal dialysis-associated peritonitis: helpful or harmful?

Relapsing, recurrent or repeat peritonitis is a devastating complication for peritoneal dialysis (PD) patients and is usually associated with poor outcomes including prolonged hospitalization, catheter removal, hemodialysis transfer and even death. Despite its critical importance and frequent occurrence, there is limited available evidence to facilitate evidence-informed treatment of PD peritonitis. This editorial comments on the findings and limitations of a randomized controlled study published in this journal, which reported that extending antibiotic treatment duration for an additional week beyond that recommended by the International Society for PD did not reduce the risk of relapsing, recurrent or repeat peritonitis, and may have increased the risk of repeat peritonitis. These results are explored in the context of the existing literature and recommendations for practice and research are provided.

Two decades of analysis of peritonitis in peritoneal dialysis in Andalusia: Epidemiological, clinical, microbiological and progression aspects

BACKGROUND

This study focuses on the main complication associated with peritoneal dialysis, peritonitis. Its relevance derives from its high morbidity, the negative effect it has on the peritoneum as a dialysis membrane and its financial cost.

METHODS

Analytical, non-interventional, observational cohort study, whose main objective is the analysis of peritonitis in patients on peritoneal dialysis in Andalusia from 1 January 1999 to 31 December 2017, with a total of 2,904 peritonitis cases. The database used is the Andalusian Autonomous Transplant Coordination Information System (SICATA).

OBJECTIVES

To ascertain how the rate of peritonitis is evolving in our community, analyse descriptive data pertaining to patients and peritonitis, ascertain the course of these infectious complications and analyse the factors that influence these cases of peritonitis and their outcomes: germ, hospitalisation and date.

RESULTS

The rate of peritonitis decreased progressively during the study period, from 0.7 peritonitis per patient in 1999 to 0.33 at the end of the period. Most infections were treated on an outpatient basis (72.5%). The most common germs were Gram-positive (55.9%), including coagulase-negative staphylococci (28.1%). Most cases of peritonitis progressed to healing (77.8%). The factors that significantly influence the need for hospitalisation and peritonitis progression were the causative germ and associated exit site infection.

CONCLUSIONS

In our population, the rate of peritonitis decreased progressively during the study period, meeting guideline recommendations.

Clinical Features and Risk Factors of Fungal Peritonitis in Children on Peritoneal Dialysis

Objective: To analyse the clinical manifestations, aetiology, prognosis, and risk factors of fungal peritonitis (FP) in children on peritoneal dialysis (PD). Methods: Among 322 children undergoing PD at Children's Hospital of Fudan University, between January 2001 and December 2019, FP cases were retrospectively analysed and compared with those of bacterial peritonitis (BP) to analyse the risk factors of FP. Results: A total of 124 cases of peritonitis were treated, including 11 FP cases in 11 children (0.0019 episodes/patient^*month) and 113 BP cases in 64 children (0.02 episodes/patient^*month). Among the 11 FP cases, 7 cases (63.64%) were caused by Candida and Candida parapsilosis (5/7) was the most common pathogen of Candida. All FP patients were converted to haemodialysis (HD) and did not resume PD during follow-up. Two patients (18.2%) died after 6 months of HD due to heart failure, 2 patients underwent kidney transplant after 2 years of infection, and the other 7 patients were still on HD. The univariate analysis showed the usage rate of antibiotics in the month before the onset of peritonitis was higher (45.45 vs. 15.93%) and the mean serum albumin was lower (31.4 vs. 34.4 g/L) in the FP group when compared with BP group (P < 0.05), while multivariate analysis showed that serum albumin ≤ 30 g/L was an independent risk factor for FP (odds ratio 4.896, 95% confidence interval 1.335-17.961). Conclusion: FP is a rare complication of PD in children, but it is associated with high technique failure. Attention should be paid to hypoproteinaemia and antibiotic use in children on PD.

Promising effect of in-situ lyticase enzyme therapy on peritoneal dialysis catheter obstruction from Acremonium fungal biofilm: A case report

We reported the first clinical use of lyticase enzyme in salvaging the peritoneal dialysis (PD) catheter obstruction from Acremonium fungal biofilm during the COVID-19 pandemic era with an impressive result in PD patient presenting with fungal peritonitis and ultrafiltration failure. The organism species was disclosed from PD effluent and catheter cultures. Adjuvant treatment with in-situ lyticase may be considered for catheter salvage therapy if the catheter could not promptly removed in time.

Along came a spider: an unusual organism identified in a peritoneal dialysis patient, a case report and literature review

Background

Peritoneal dialysis-associated peritonitis can uncommonly be caused by fungal infections. When they do present, they are associated with significant mortality and morbidity. We describe a case where a sample of peritoneal dialysate fluid grew Rhodotorula muciliginosa, a yeast organism present in the normal environment which has previously been reported as rarely causing peritonitis. We believe this is the first case where the Rhodotorula spp. and its origin has been identified.

Case presentation

A 20 year old male grew Rhodotorula muciliginosa from his peritoneal dialysis fluid on three separate occasions when a fluid sample was sent following a disconnection and subsequent set change. He was not systemically unwell and his peritoneal dialysate was clear. As Rhodotorula spp. is exceedingly difficult to treat our patient had his Tenchkoff catheter removed. Subsequent samples of soil and sand from his bearded dragon and Chilean tarantula cases, kept in his bedroom where dialysis occurred, were tested. The tarantula sand was identified as the source of the Rhodotorula spp. Of note, Candida was isolated from sand from the bearded dragon case. Once his Tenchkoff was removed he was treated with an intravenous course of antifungal therapy. He has since had a new Tenchkoff catheter inserted and recommenced PD following education around pets and hygiene.

Conclusions

In this era where people are keeping increasingly rare and unusual wildlife in their homes, this case highlights the need for clinician and nursing staff awareness of a patient’s home environment and hobbies when they are undergoing peritoneal dialysis. Sand from our patient’s tarantula case grew the colonising organism but interestingly soil from his bearded dragon case also isolated candida. This can also cause difficult to treat peritonitis.

Continuous ambulatory peritoneal dialysis-associated Histoplasma capsulatum peritonitis: a case report and literature review

Background

Fungal peritonitis (FP) is a rare complication of peritoneal dialysis. We herein describe the second case in Asia of Histoplasma capsulatum peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD).

Case presentation

An 85-year-old woman with end-stage renal disease (ESRD) who had been on CAPD for 3 years and who had a history of 3 prior episodes of peritonitis presented with intermittent abdominal pain for 2 weeks and high-grade fever for 3 days. Elevated white blood cell (WBC) count and rare small oval budding yeasts were found in her peritoneal dialysis (PD) fluid. From this fluid, a white mold colony was observed macroscopically after 7 days of incubation, and numerous large, round with rough-walled tuberculate macroconidia along with small smooth-walled microconidia were observed microscopically upon tease slide preparation, which is consistent with H. capsulatum. The peritoneal dialysis (PD) catheter was then removed, and it also grew H. capsulatum after 20 days of incubation. The patient was switched from CAPD to hemodialysis. The patient was successfully treated with intravenous amphotericin B deoxycholate (AmBD) for 2 weeks, followed by oral itraconazole for 6 months with satisfactory result. The patient remains on hemodialysis and continues to be clinically stable.

Conclusion

H. capsulatum peritonitis is an extremely rare condition that is associated with high morbidity and mortality. Demonstration of small yeasts upon staining of PD fluid, and isolation of slow growing mold in the culture of clinical specimen should provide important clues for diagnosis of H. capsulatum peritonitis. Prompt removal of the PD catheter and empirical treatment with amphotericin B or itraconazole is recommended until the culture results are known.

Peritoneal Dialysis-Associated Peritonitis: Suggestions for Management and Mistakes to Avoid

Peritonitis is a common complication of peritoneal dialysis that is associated with substantial morbidity and mortality. Peritonitis increases treatment costs and hospitalization events and is the most common reason for transfer to hemodialysis. Although there is much focus on preventing peritoneal dialysis–associated peritonitis, equally as important is appropriate management to minimize the morbidity of a peritonitis episode when it has occurred. Despite the presence of international guidelines on peritonitis treatment, the evidence base to support optimal peritonitis treatment practices is lacking, leaving the practitioner to rely on clinical experience and extrapolate from across other infection treatment practices. This article reviews common mistakes and misconceptions that we have observed in the management of peritonitis that may compromise treatment success. It also provides suggestions on common controversial aspects of peritonitis management based on the best available literature. Although the use of the word mistakes is somewhat controversial and subjective, we acknowledge that evidence is lacking and have based many of our suggestions on clinical judgment, experience, and available data.

Regional variation in the treatment and prevention of peritoneal dialysis-related infections in the Peritoneal Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Peritoneal dialysis (PD)-related infections lead to significant morbidity. The International Society for Peritoneal Dialysis (ISPD) guidelines for the prevention and treatment of PD-related infections are based on variable evidence. We describe practice patterns across facilities participating in the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS).

METHODS

PDOPPS, a prospective cohort study, enrolled nationally representative samples of PD patients in Australia/New Zealand (ANZ), Canada, Thailand, Japan, the UK and the USA. Data on PD-related infection prevention and treatment practices across facilities were obtained from a survey of medical directors'.

RESULTS

A total of 170 centers, caring for >11 000 patients, were included. The proportion of facilities reporting antibiotic administration at the time of PD catheter insertion was lowest in the USA (63%) and highest in Canada and the UK (100%). Exit-site antimicrobial prophylaxis was variably used across countries, with Japan (4%) and Thailand (28%) having the lowest proportions. Exit-site mupirocin was the predominant exit-site prophylactic strategy in ANZ (56%), Canada (50%) and the UK (47%), while exit-site aminoglycosides were more common in the USA (72%). Empiric Gram-positive peritonitis treatment with vancomycin was most common in the UK (88%) and USA (83%) compared with 10-45% elsewhere. Empiric Gram-negative peritonitis treatment with aminoglycoside therapy was highest in ANZ (72%) and the UK (77%) compared with 10-45% elsewhere.

CONCLUSIONS

Variation in PD-related infection prevention and treatment strategies exist across countries with limited uptake of ISPD guideline recommendations. Further work will aim to understand the impact these differences have on the wide variation in infection risk between facilities and other clinically relevant PD outcomes.

Infection Prophylaxis in Peritoneal Dialysis Patients: Results from an Australia/New Zealand Survey

Background

Clinical practice guidelines aim to reduce the rates of peritoneal dialysis (PD)-related infections, a common complication of PD in end-stage kidney disease patients. We describe the clinical practices used by Australian and New Zealand nephrologists to prevent PD-related infections in PD patients.

Methods

A survey of PD practices in relation to the use of antibiotic and antifungal prophylaxis in PD patients was conducted of practicing nephrologists identified via the Australia and New Zealand Society of Nephrology (ANZSN) membership in 2013.

Results

Of 333 nephrologists approached, 133 (39.9%) participated. Overall, 127 (95.5%) nephrologists prescribed antibiotics at the time of Tenckhoff catheter insertion, 85 (63.9%) routinely screened for nasal S. aureus carriage, with 76 (88.4%) reporting they treated S. aureus carriers with mupirocin ointment. Following Tenckhoff catheter insertion, 79 (59.4%) prescribed mupirocin ointment at the exit site or intranasally, and 93 (69.9%) nephrologists routinely prescribed a course of oral antifungal agent whenever their PD patients were given a course of antibiotics.

Conclusions

Although the majority of nephrologists prescribe antibiotics at the time of Tenckhoff catheter insertion, less than 70% routinely prescribe mupirocin ointment and/or prophylactic antifungal therapy. This variation in practice in Australia and New Zealand may contribute to the disparity in PD-related infection rates that is seen between units.

Polymicrobial interactions involving fungi and their importance for the environment and in human disease

Understanding polymicrobial interactions involving fungi in the environment and the human mycobiome is necessary to address environmental and medically related problems such as drought or antimicrobial resistance. The diversity of these interactions highlights the complexity of fungi, considering how some interactions can be antagonistic, while others synergistic. Over the years, an increase in studies on the mycobiome have revealed similarities between the human and environmental hosts. More recently, studies have focused on microbial commensal relationships and identifying causative agents of human disease. The overlap of some of these interactions is impossible to ignore, indicating that there are areas for medical exploitation that need to be further investigated. This review provides the latest advances in polymicrobial interactions involving fungi and discusses the importance of the fungal lifestyle in the environment and in human disease.

Spectrum of Trained Innate Immunity Induced by Low-Virulence Candida Species against Lethal Polymicrobial Intra-abdominal Infection

Polymicrobial intra-abdominal infections (IAI) are clinically prevalent and cause significant morbidity and mortality, especially those involving fungi. Our laboratory developed a mouse model of polymicrobial IAI and demonstrated that coinfection with Candida albicans and Staphylococcus aureus (C. albicans/S. aureus) results in 80 to 90% mortality in 48 to 72 h due to robust local and systemic inflammation.

Polymicrobial intra-abdominal infections (IAI) are clinically prevalent and cause significant morbidity and mortality, especially those involving fungi. Our laboratory developed a mouse model of polymicrobial IAI and demonstrated that coinfection with Candida albicans and Staphylococcus aureus (C. albicans/S. aureus) results in 80 to 90% mortality in 48 to 72 h due to robust local and systemic inflammation. Surprisingly, inoculation with Candida dubliniensis and S. aureus resulted in minimal mortality, and rechallenge of mice with lethal C. albicans/S. aureus conferred >90% protection up to 60 days postinoculation. Protection was mediated by Gr-1⁺ polymorphonuclear leukocytes, indicating a novel form of trained innate immunity (TII). The purpose of this study was to determine the microbial requirements and spectrum of innate-mediated protection. In addition to Candida dubliniensis, several other low-virulence Candida species (C. glabrata, C. auris, and C. albicansefg1Δ/Δ cph1Δ/Δ) and Saccharomyces cerevisiae conferred significant protection with or without S. aureus. For C. dubliniensis-mediated protection, hyphal formation was not required, with protection conferred as early as 7 days after primary challenge but not at 120 days, and also following multiple lethal C. albicans/S. aureus rechallenges. This protection also extended to a lethal intravenous (i.v.) C. albicans challenge but had no effect in the C. albicans vaginitis model. Finally, studies revealed the ability of the low-virulence Candida species that conferred protection to invade the bone marrow by 24 h post-primary challenge, with a positive correlation between femoral bone marrow fungal infiltration at 48 h and protection upon rechallenge. These results support and further extend the characterization of this novel TII in protection against lethal fungal-bacterial IAI and sepsis.

Candida/Staphylococcal Polymicrobial Intra-Abdominal Infection: Pathogenesis and Perspectives for a Novel Form of Trained Innate Immunity

Polymicrobial sepsis is difficult to diagnose and treat and causes significant morbidity and mortality, especially when fungi are involved. In vitro, synergism between Candida albicans and various bacterial species has been described for many years. Our laboratory has developed a murine model of polymicrobial intra-abdominal infection with Candida albicans and Staphylococcus aureus, demonstrating that polymicrobial infections cause high levels of mortality, while monoinfections do not. By contrast, closely related Candida dubliniensis does not cause synergistic lethality and rather provides protection against lethal polymicrobial infection. This protection is thought to be driven by a novel form of trained innate immunity mediated by myeloid-derived suppressor cells (MDSCs), which we are proposing to call "trained tolerogenic immunity". MDSC accumulation has been described in patients with sepsis, as well as in in vivo sepsis models. However, clinically, MDSCs are considered detrimental in sepsis, while their role in in vivo models differs depending on the sepsis model and timing. In this review, we will discuss the role of MDSCs in sepsis and infection and summarize our perspectives on their development and function in the spectrum of trained innate immune protection against fungal-bacterial sepsis.

Intracatheter Antifungal Lock Leading to Detrimental Complications

As peritoneal dialysis (PD)-related fungal infection is associated with a high mortality rate, the international guidelines recommend immediate removal of the PD catheter in conjunction with at least 2-weeks of antifungal treatment. Some authors have reported successful management of such cases without removing the PD catheter - by instilling an antifungal lock into the retained PD catheter. However, the use of antifungal locks has generally not been well accepted as the standard treatment for fungal peritonitis in PD patients. We report two cases where antifungal lock were performed in PD patients presented with PD-related fungal infection that not only had no effect on abating the infection but also causing paradoxical outcomes.

Fungal peritonitis in peritoneal dialysis: 5-year review from a North China center

PURPOSE

Fungal peritonitis (FP) is a rare but devastating complication in peritoneal dialysis (PD), accounting for high rates of technique failure, morbidity and mortality. This study was conducted to investigate FPs with regard to peritonitis rate, microbiology testing, patient characteristics, clinical features, antifungal treatments, and clinical outcomes in patients on PD.

METHODS

This single-center study retrospectively reviewed all FP episodes diagnosed from June 1, 2012 to June, 2017. All FPs were matched in a 1:5 ratio with PD patients diagnosed with bacterial peritonitis. Clinical, biochemical characteristics and detailed data on peritonitis episodes were recorded.

RESULTS

Eleven fungal peritonitis episodes (rate of 0.0067 episodes per patient-year on dialysis) were identified. All FPs were caused by Candida species (identification and antifungal susceptibility testing were performed with VITEK 2^® compact system), including C. albicans (6/11), C. parapsilosis (4/11) and C. krusei (1/11). Except C. krusei, no Candida resistance to fluconazole was detected. Compared to bacterial peritonitis (matched cases, n = 55), FP group showed higher rate of previous antibiotic use (p = 0.002), higher total effluent cell count (p = 0.007), and lower serum albumin (p = 0.01), higher rate of infection-related surgery (p < 0.001), HD transfer (p = 0.001), and all-cause death (p = 0.006). High prevalence (≥ 50%) of female gender, anuria, CCI ≥ 4, hypoalbuminemia, anemia, and hypokalemia were also observed in FP patients. More than half of the FP patients presented gastrointestinal symptoms (7/11) and extraperitoneal infection (6/11). Eight (72.7%) patients had catheter surgically removed with a median 5.5 lag days, four (36.4%) patients died within 3 months and six (54.5%) cases led to technique failure.

CONCLUSIONS

FP results in high rates of catheter loss and all-cause mortality in 3 months of follow-up, candida species were the commonest pathogens in our center. Variations of clinical features and susceptibility patterns were observed. Gastrointestinal disorders maybe a potential risk factor for FP.

Fungal peritonitis in peritoneal dialysis: a 34-year single centre evaluation

Backgound

Fungal peritonitis (FP) is one of the most important causes of peritoneal dialysis (PD) failure, often burdened by increased morbility and mortality. This study evaluates the clinical course of FP cases that arose between 1983 and 2016 in a single PD unit.

Methods

We conducted a retrospective observational analysis of FP episodes recorded in the Baxter POET (Peritonitis Organism Exit sites Tunnel infections) registry and clinical records. FP incidence rate, PD and patients’ survival and clinical characteristics of the study population were analysed, taking into account the evolution of clinical practice during the study period as a result of technical innovation, scientific evidence and guideline history.

Results

Fourteen FP cases (2.8%) were detected. The overall incidence of PD peritonitis was one episode/27 patient-months. Candida parapsilosis was the most frequently (50%) detected yeast. Seventy-five per cent of cases were considered secondary FP. This group experienced 2.6±1.7 bacterial peritonitis before FP, most frequently due to Staphylococcus and Enterococcus species. Most patients were treated with fluconazole for ≥8 days. All subjects were hospitalized for a median time of 25 days. Tenckhoff catheter removal occurred in all cases of FP and all patients were transferred to haemodialysis. Two patients died. From December 2010 to December 2016, no FP episodes were recorded.

Conclusions

FP is confirmed as a significant cause of PD drop out and increases patients’ mortality risk. Prompt diagnosis of FP, targeted antifugal therapy and rapid PD catheter removal are essential strategies for improved patient and PD survival.

Identification of Specific Components of the Eicosanoid Biosynthetic and Signaling Pathway Involved in Pathological Inflammation during Intra-abdominal Infection with Candida albicans and Staphylococcus aureus

Polymicrobial intra-abdominal infections (IAIs) are a significant cause of morbidity and mortality, particularly when fungal pathogens are involved. Our experimental murine model of IAI involving intraperitoneal inoculation of Candida albicans and Staphylococcus aureus results in synergistic lethality (∼80%) due to exacerbated inflammation. Monomicrobial infection results in no mortality, despite a microbial burden and dissemination similar to those in a coinfection. In the coinfection model, the immunomodulatory eicosanoid prostaglandin E₂ (PGE₂) was determined to be necessary and sufficient to induce mortality, implicating PGE₂ as the central mediator of the amplified inflammatory response. The aim of this study was to identify key components of the PGE₂ biosynthetic and signaling pathway involved in the inflammatory response and explore whether these can be targeted to prevent or reduce mortality. Using selective pharmacological inhibitors of cyclooxygenases (COX) or PGE₂ receptor antagonists in the C. albicans-S. aureus IAI mouse model, we found that inhibition of COX and/or blocking of PGE₂ receptor 1 (EP1) or PGE₂ receptor 3 (EP3) signaling reduced proinflammatory cytokine production, promoted interleukin-10 production, reduced cellular damage in the peritoneal cavity, and, most importantly, significantly improved survival. The greatest effect on survival was obtained by the simultaneous inhibition of COX-1 activity and EP1 and EP3 receptor signaling. Importantly, early inhibition of PGE₂ pathways dramatically improved the survival of fluconazole-treated mice compared with that achieved with fluconazole treatment alone. These findings indicate that COX-1 and the EP1 and EP3 receptors mediate the downstream pathological effects of PGE₂ during polymicrobial IAI and may serve as effective therapeutic targets.

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.

Immune Protection against Lethal Fungal-Bacterial Intra-Abdominal Infections

Polymicrobial intra-abdominal infections (IAIs) are clinically prevalent and cause significant morbidity and mortality, especially those involving fungi. Our laboratory developed a mouse model of IAI and demonstrated that intraperitoneal inoculation with Candida albicans or other virulent non-albicans Candida (NAC) species plus Staphylococcus aureus resulted in 70 to 80% mortality in 48 to 72 h due to robust local and systemic inflammation (sepsis). Surprisingly, inoculation with Candida dubliniensis or Candida glabrata with S. aureus resulted in minimal mortality, and rechallenge of these mice with lethal C. albicans/S. aureus (i.e., coninfection) resulted in >90% protection. The purpose of this study was to define requirements for C. dubliniensis/S. aureus-mediated protection and interrogate the mechanism of the protective response. Protection was conferred by C. dubliniensis alone or by killed C. dubliniensis plus live S. aureus. S. aureus alone was not protective, and killed S. aureus compromised C. dubliniensis-induced protection. C. dubliniensis/S. aureus also protected against lethal challenge by NAC plus S. aureus and could protect for a long-term duration (60 days between primary challenge and C. albicans/S. aureus rechallenge). Unexpectedly, mice deficient in T and B cells (Rag-1 knockouts [KO]) survived both the initial C. dubliniensis/S. aureus challenge and the C. albicans/S. aureus rechallenge, indicating that adaptive immunity did not play a role. Similarly, mice depleted of macrophages prior to rechallenge were also protected. In contrast, protection was associated with high numbers of Gr-1^hi polymorphonuclear leukocytes (PMNLs) in peritoneal lavage fluid within 4 h of rechallenge, and in vivo depletion of Gr-1⁺ cells prior to rechallenge abrogated protection. These results suggest that Candida species can induce protection against a lethal C. albicans/S. aureus IAI that is mediated by PMNLs and postulated to be a unique form of trained innate immunity.

Polymicrobial intra-abdominal infections are clinically devastating infections with high mortality rates, particularly those involving fungal pathogens, including Candida species. Even in patients receiving aggressive antimicrobial therapy, mortality rates remain unacceptably high. There are no available vaccines against IAI, which is complicated by the polymicrobial nature of the infection. IAI leads to lethal systemic inflammation (sepsis), which is difficult to target pharmacologically, as components of the inflammatory response are also needed to control the infection. Our studies demonstrate that prior inoculation with low-virulence Candida species provides strong protection against subsequent lethal infection with C. albicans and S. aureus. Surprisingly, protection is long-lived but not mediated by adaptive (specific) immunity. Instead, protection is dependent on cells of the innate immune system (nonspecific immunity) and provides protection against other virulent Candida species. This discovery implies that a form of trained innate immunity may be clinically effective against polymicrobial IAI.

Center Effects and Peritoneal Dialysis Peritonitis Outcomes: Analysis of a National Registry

BACKGROUND

Peritonitis is a common cause of technique failure in peritoneal dialysis (PD). Dialysis center-level characteristics may influence PD peritonitis outcomes independent of patient-level characteristics.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Using Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) data, all incident Australian PD patients who had peritonitis from 2004 through 2014 were included.

PREDICTORS

Patient- (including demographic data, causal organisms, and comorbid conditions) and center- (including center size, proportion of patients treated with PD, and summary measures related to type, cause, and outcome of peritonitis episodes) level predictors.

OUTCOMES & MEASUREMENT

The primary outcome was cure of peritonitis with antibiotics. Secondary outcomes were peritonitis-related catheter removal, hemodialysis therapy transfer, peritonitis relapse/recurrence, hospitalization, and mortality. Outcomes were analyzed using multilevel mixed logistic regression.

RESULTS

The study included 9,100 episodes of peritonitis among 4,428 patients across 51 centers. Cure with antibiotics was achieved in 6,285 (69%) peritonitis episodes and varied between 38% and 86% across centers. Centers with higher proportions of dialysis patients treated with PD (>29%) had significantly higher odds of peritonitis cure (adjusted OR, 1.21; 95% CI, 1.04-1.40) and lower odds of catheter removal (OR, 0.78; 95% CI, 0.62-0.97), hemodialysis therapy transfer (OR, 0.78; 95% CI, 0.62-0.97), and peritonitis relapse/recurrence (OR, 0.68; 95% CI, 0.48-0.98). Centers with higher proportions of peritonitis episodes receiving empirical antibiotics covering both Gram-positive and Gram-negative organisms had higher odds of cure with antibiotics (OR, 1.22; 95% CI, 1.06-1.42). Patient-level characteristics associated with higher odds of cure were younger age and less virulent causative organisms (coagulase-negative staphylococci, streptococci, and culture negative). The variation in odds of cure across centers was 9% higher after adjustment for patient-level characteristics, but 66% lower after adjustment for center-level characteristics.

LIMITATIONS

Retrospective study design using registry data.

CONCLUSIONS

These results suggest that center effects contribute substantially to the appreciable variation in PD peritonitis outcomes that exist across PD centers within Australia.

Oral Yeast Colonization and Fungal Infections in Peritoneal Dialysis Patients: A Pilot Study

Peritonitis and exit-site infections are important complications in peritoneal dialysis (PD) patients that are occasionally caused by opportunistic fungi inhabiting distant body sites. In this study, the oral yeast colonization of PD patients and the antifungal susceptibility profile of the isolated yeasts were accessed and correlated with fungal infection episodes in the following 4 years. Saliva yeast colonization was accessed in 21 PD patients and 27 healthy controls by growth in CHROMagar-Candida® and 18S rRNA/ITS sequencing. PD patients presented a lower oral yeast prevalence when compared to controls, namely, Candida albicans. Other species were also isolated, Candida glabrata and Candida carpophila. The antifungal susceptibility profiles of these isolates revealed resistance to itraconazole, variable susceptibility to caspofungin, and higher MIC values of posaconazole compared to previous reports. The 4-year longitudinal evaluation of these patients revealed Candida parapsilosis and Candida zeylanoides as PD-related exit-site infectious agents, but no correlation was found with oral yeast colonization. This pilot study suggests that oral yeast colonization may represent a limited risk for fungal infection development in PD patients. Oral yeast isolates presented a variable antifungal susceptibility profile, which may suggest resistance to some second-line drugs, highlighting the importance of antifungal susceptibility assessment in the clinical practice.

Apoptosis inhibitor of macrophage ameliorates fungus-induced peritoneal injury model in mice

Fungal peritonitis in a patient on peritoneal dialysis (PD) is a refractory injury accompanied by severe inflammation, predisposing patients to a poor prognosis. Defective clearance of necrotic tissue interferes with amelioration of tissue injury and induces abnormal tissue remodeling. In the recent reports, apoptosis inhibitor of macrophage (AIM, also called CD5L) prevents obesity, hepatocellular carcinoma and acute kidney injury. Here, we investigated potential roles of AIM in prevention of progression of fungal peritonitis models. AIM^−/− mice subjected to zymosan-induced peritonitis exhibited progressive inflammation and sustained peritoneal necrosis tissue on day 28 after the disease induction, whereas there was an improvement in AIM^+/+ mice. This appeared to be caused by deposition of AIM at the necrotic peritoneum in AIM^+/+ mice. In vitro, AIM enhanced the engulfment of necrotic debris by macrophages derived from zymosan-induced peritonitis, M1- and M2a-like bone marrow derived macrophages, as well as by mesothelial cells. In addition, administration of recombinant AIM dramatically ameliorated severe inflammation associated with necrosis in zymosan-induced peritonitis of AIM^−/− mice. Our observations suggest that AIM appears to be involved in the repair process of zymosan-induced peritonitis, and thus, could be the basis of development of new therapeutic strategies for PD-related fungal peritonitis.

Cryptococcosis in HIV-negative Patients with Renal Dialysis: A Retrospective Analysis of Pooled Cases

Cryptococcosis is a lethal fungal infection mainly caused by Cryptococcus neoformans/C. gattii species. Currently, our understanding of cryptococcosis episodes in HIV-negative patients during renal dialysis remains scarce and fragmented. Here, we performed an analysis of pooled cases to systemically summarize the epidemiology and clinical characteristics of cryptococcosis among HIV-negative patients with renal dialysis. Using pooled data from our hospital and studies identified in four medical databases, 18 cases were identified and analyzed. The median duration time of renal dialysis for peritoneal renal dialysis and hemodialysis cases was 8 months and 36 months, respectively. Several non-neoformans/gattii species were identified among the renal dialysis recipients with cryptococcosis, particularly Cryptococcus laurentii and Cryptococcus albidus, which share similar clinical manifestations as those caused by C. neoformans and C. gattii. Our analyses suggest that physicians should consider the possibility of the occurrence of cryptococcosis among renal dialysis recipients even when cryptococcal antigen test result is negative. The timely removal of the catheter is crucial for peritoneal dialysis patients with cryptococcosis. In addition, there is a need for optimized antifungal treatment strategy in renal dialysis recipients with cryptococcal infections.