Staphylococcus lugdunensis Peritoneal Dialysis Related Peritonitis: a Matched Comparative Analysis

Rationale & Objective. Staphylococcus lugdunensis (S.lugdunensis) is a coagulase-negative staphylococcus (CoNS) species that has been increasingly recognized to cause serious infections with virulence resembling staphylococcus aureus (S.aureus). No studies have evaluated the characteristics and outcomes of patients with S.lugdunensis peritoneal dialysis related peritonitis (peritonitis) compared those with S.aureus peritonitis. We aim to evaluate the clinical course of peritonitis as caused by these organisms. Study Design Retrospective matched comparative analysis involving a single tertiary centre between July 2000 and July 2020 Setting & Participants 48 episodes of S.aureus peritonitis were matched to 19 cases of S.lugdunensis peritonitis. Analytical Approach The cases were individually matched for year of the peritonitis, gender, age (±10 years) and Charlson Comorbidity index (±3). A comparative analysis was performed between the two organisms. Outcome includes responses at day 5 of peritonitis and rate of complete response. Results There is a higher predilection of diabetes in those with S.aureus peritonitis than those with S.lugdunensis (64.6% vs 31.6%; p=0.03). Patients with S.aureus peritonitis also have a much higher total cells count at presentation (4463.9±5479.5 vs 1807.9±3322.7; p=0.05); a higher prevalence of poor response at day 5 (50.0% vs 15.8%; p=0.03); lower rate of complete response (64.6% vs 94.7%; p=0.01) and are more prone to relapse with the same organism (29.2% vs 0% respectively; p=0.01) as compared to those with S.lugdunensis. Limitations The result in this small retrospective study involving a single centre may not be generalisable to other centres. There is also no data on other CoNS such as Staphylococcus epidermidis, the same family S.lugdunensis belongs to, for the comparative analysis. Conclusions Although S.aureus peritonitis is more virulent with significant morbidity, S.lugdunensis can cause similarly serious peritonitis. This largest cases series of S.lugdunensis peritonitis enabled better characterisation in the clinical features and outcomes of patients with S.lugdunensis peritonitis.