Kocuria Rhizophila peritonitis in peritoneal dialysis: About 2 cases and review of the literature

Abstract

Summary

The authors report two clinical cases of peritonitis caused by Kocuria rhizophila, an uncommon but pathogenic bacterium, that occurred in a dialysis center over a three-month period in 2022. These cases required removal of the peritoneal dialysis catheter, illustrating the potential severity of these infections. The authors describe the clinicobiologic features of these peritonitis and highlight the difficulty in distinguishing Kocuria from other gram-positive cocci, such as staphylococci, due to their morphologic similarity and the need for accurate identification for appropriate treatment.

The discussion focuses on the incidence and management of Kocuria peritonitis in France, based on an observational cohort study using data from the Registre de Dialyse Péritonéale de Langue Française (RDPLF) between January 2018 and May 2023. The study found that Kocuria peritonitis accounted for 3.5% of documented peritonitis, with Kocuria rhizophila being the most commonly identified. The study highlights a high recurrence rate and the frequent need for catheter removal, underscoring the severity of these infections.

Conclusion: The authors suggest that rapid catheter removal and replacement should be considered in cases of Kocuria rhizophila peritonitis, given the high rate of relapse. They also call for increased vigilance and close follow-up of patients treated conservatively with antibiotics to minimize the risk of relpase and technical failure, suggesting the need for therapeutic strategies tailored to this specific pathogen.

Introduction

LIST OF ABBREVIATIONS

GPC: Gram-Positive Cocci

AOMI: Obliterative Arteriopathy of the Lower Limbs

CAPD: Continuous Ambulatory Peritoneal Dialysis

APD: Automated Peritoneal Dialysis

IP: Intraperitoneal

NPC:Non-Polymorphonuclear Cells

CRP: Non-Polymorphonuclear Cells

RDPLF: French Language Peritoneal Dialysis Registry

Peritonitis currently represents 14% of the cases necessitating a transition from peritoneal dialysis to hemodialysis in France and accounts for 3% of all mortality rates associated with dialysis[1]. Innovations in both the technical and medical spheres, including the implementation of the «flush before fill» technique, enhanced antisepsis protocols, and the application of mupirocin, in conjunction with the establishment of therapeutic patient education initiatives, have contributed to a decrease in the incidence of peritonitis. This reduction is particularly notable in the case of gram-positive cocci (GPC) infections, which are prevalent among diabetic individuals.

The capacity to identify causative germs is not consistently achievable, with the prevalence of culture-negative peritonitis exhibiting significant variation, ranging from 10% to 50% across different facilities[2]. The process for germ identification necessitates a prompt analysis of the effluent dialysate, which is incubated in blood culture bottles (e.g., BACTEC, Kent, UK) following a minimum dwell time of two hours. Employing an optimal dialysate culture methodology involving centrifugation of the dialysate followed by resuspension of the supernatant in a culture medium should curtail the incidence of undocumented peritonitis to below 10%. Typically, a phenotypic analysis utilizing mass spectrometry (bioMérieux VITEK MS) is conducted initially, with subsequent identification of bacteria through automated biochemical galleries (bioMérieux VITEK 2) in cases where spectrometry is inconclusive.

Staphylococci, encompassing coagulase-positivestaphylococci, such asStaphylococcus aureus, and coagulase-negativestaphylococci, predominantly account for GPC-related peritonitis cases. In both micro and macroscopic evaluations of cultures, it is common to encounter difficulties distinguishing coagulase-negative staphylococci from other GPC species, such asKocuria.

Species within theMicrococcusandKocuria genera, members of theMicrococcaceaefamily, are characterized as cluster or tetrad-forming GPCs. These species are distinguishable fromstaphylococciby their larger size and more pronounced yellow pigmentation under light microscopy. Although typically saprophytic on human skin, mucous membranes, and oropharynx, they can become pathogenic in the context of immunodepression. Concerning peritoneal dialysis, these bacteria have been implicated in cases of peritonitis.

The International Society for Peritoneal Dialysis has issued guidelines for the probabilistic antibiotic treatment of peritonitis, which were recently summarized by Taghavi and Dratwa[3]. These guidelines primarily focus on GPCs and gram-negative bacilli; however, they do not explicitly address peritonitis caused byMicrococcusandKocuriaspecies.

In this report, we present two instances ofKocuria rhizophilaperitonitis identified at our facility within 3 months in 2022, both of which necessitated the removal of the peritoneal dialysis catheter. The objective of this study is to delineate the clinico-biological profiles and outcomes of theseK. rhizophilaperitonitis cases and compare the findings with data recorded in the French Language Peritoneal Dialysis Registry (RDPLF) as well as existing literature on the subject.

Clinical Cases

Case 1

Case 1 involves a 70-year-old male, presenting with chronic renal failure attributed to probable nephroangiosclerosis. His medical history included active smoking, exogenous factors, and endovascular revascularization for stage 3 obliterative arteriopathy of the lower limbs (AOMI). He had been undergoing continuous ambulatory peritoneal dialysis (CAPD) for 5 years, with three daily exchanges. Two years prior, he experiencedStreptococcus salivariusandStreptococcus vestibularisperitonitis, which responded favorably to intraperitoneal (IP) cefazolin.

Upon first evaluation, the patient presented with a compromised infusion line, necessitating its replacement, yet there were no clinical or biological indicators initially suggesting peritonitis. Subsequent routine analysis of his dialysate identified the presence of Micrococcus luteus. This bacterium was interpreted as a contaminant due to its non-pathogenic nature and the absence of increased cellularity in the dialysate, indicating a lack of inflammatory response typically associated with infection.

Despite developing severe abdominal pain, widespread defensiveness, and functional ileus 3 weeks later, the patient remained apyretic and showed no signs of hemodynamic compromise. The effluent appeared turbid, and analysis confirmed peritonitis with a dialysate hypercellularity of 9440 elements/mm3, of which 80% were non-polymorphonuclear cells (NPCs).

The patient’s blood analysis indicated a biological inflammatory syndrome with a C-reactive protein (CRP) level of 125 mg/L, notably without hyperleukocytosis. Plasma albumin concentration was measured at 30 g/L. In accordance with local protocols and International Society for Peritoneal Dialysis recommendations, empiric treatment commenced with IP cefazolin and ceftazidime. Subsequent direct examination detected the presence of GPCs, leading to the discontinuation of ceftazidime and the continuation of cefazolin as monotherapy.

The patient’s condition rapidly improved, as evidenced by diminished pain following lavage and the placement of a nasogastric tube for functional ileus. However, cultures of the dialysate remained positive forK. rhizophilafor 6 days, prompting the substitution of cefazolin with IP vancomycin, pending the results of susceptibility testing. The susceptibility testing revealed a strain responsive to multiple antibiotics. Cultures became sterile after 48 hours of vancomycin therapy, which was extended for a total duration of 21 days. After treatment, the dialysate analysis showed no microbial growth and normalization of peritoneal cellularity to 17 elements/mm3, albeit with a predominance of 68% NPCs. The CRP level remained mildly elevated at 40 mg/L.

Ten days post-antibiotic therapy, the patient experienced severe abdominal pain and diffuse tenderness. The dialysate appeared cloudy, and analysis confirmed a recurrence of peritonitis, with 5760 nucleated cells/mm3, including 89% NPCs. Blood tests indicated an elevated inflammatory response, with a CRP level

.....