Staphylococcus lugdunensis in blood cultures of dialysis patients: a single-center retrospective observational study of detection rate, antimicrobial susceptibility, and clinical significance

Abstract Background Bloodstream infection is a leading cause of hospitalization and death in maintenance dialysis, with the vascular access and foreign material as principal portals of entry. Staphylococcus lugdunensis is a coagulase-negative staphylococcus resembling Staphylococcus aureus , yet its epidemiology in dialysis patients is unknown. Methods We retrospectively analyzed 5826 blood culture sets from dialysis patients with suspected bacteremia between April 2020 and December 2022 at a hospital managing more than 700 hemodialysis patients. Identification and susceptibility testing used the MicroScan WalkAway system with Clinical and Laboratory Standards Institute breakpoints. Sets, episodes, and patients were analyzed as distinct units. The set-level yearly trend was explored with the Cochran–Armitage test. Results Of the 5826 sets, 980 were culture-positive, and S. lugdunensis was detected in 42 (0.7% of all sets; 4.3% of positive sets), corresponding to 23 episodes in 21 patients. Among the 288 patients with at least one positive set, S. lugdunensis was recovered from 21 (7.3%), and from 12 (4.2%) when required in two or more sets. Three patients died; one death was unrelated, and the organism’s contribution to two deaths from polymicrobial sepsis could not be established. Seven episodes were vascular access infections; foreign material was present in 13 and involved in 7. A single set was positive in ten episodes; in five, a clinically suspected infection at a compatible site was recorded, with local access or graft signs at presentation in four and infective endocarditis diagnosed on subsequent evaluation in one; organism-specific attribution was not confirmed. Penicillin resistance was found in 16 of 23 isolates (69.6%); all isolates were phenotypically methicillin-susceptible. The organism’s share of culture-positive sets rose from 2.1% to 7.2% (exploratory set-level P = 0.003), whereas episodes numbered three, ten, and ten. Conclusions At this dialysis facility, S. lugdunensis accounted for 4.3% of culture-positive sets, was associated with vascular access or involved foreign material in 8 of 23 episodes, and was mostly penicillin-resistant. Whether this proportion exceeds that elsewhere, and whether it is increasing, requires confirmation in other dialysis units. A single positive set should not be dismissed without clinical assessment.