Bacterial biofilm on peritoneal dialysis catheters: A retrospective observational study.

Objective: Biofilm formation significantly impacts infection risks in peritoneal dialysis (PD) patients. However, few studies focused on biofilms on PD catheters. This study aims to explore the formation and characteristics of bacterial biofilm on PD catheters. Methods: A retrospective study was conducted on maintenance PD patients from January 2007 to January 2024. We summarized the general characteristics of the patients, the reasons for catheter removal, scanning electron microscopy (SEM) results of the PD catheter, and bacterial culture results from the PD effluent. The selected patients were divided into two groups: catheter removal due to peritonitis group (20 cases) and catheter removal due to non-peritonitis group (8 cases). Results: (1) The average dialysis duration in catheter removal due to peritonitis group was 84.2 ± 46.6 months, significantly longer than that in catheter removal due to non-peritonitis group (21.8 ± 18.7 months). Thirteen patients (65.5%) in catheter removal due to peritonitis group had a history of peritonitis before the current episode, whereas none in catheter removal due to non-peritonitis group had experienced it previously (p = 0.002). (2) Bacterial biofilm was detected in 20 (71.4%) out of 28 patients. Of these, bacterial biofilm was found in 18 patients (90.0%) in catheter removal due to peritonitis group, compared to only 2 patients (25.0%) in catheter removal due to non-peritonitis group (p = 0.002). SEM revealed that the bacterial biofilm forms present on the PD catheters were exclusively cocci biofilms. The bacterial culture results from the PD fluid of patients in catheter removal due to peritonitis group indicated that the three most prevalent pathogens were Escherichia coli (7/20), methicillin-sensitive Staphylococcus aureus (3/20), and Staphylococcus epidermidis (3/20). Conclusion: Bacterial biofilm formation on PD catheters is common among long-term PD patients. It is important to note that not all PD catheters removed due to peritonitis exhibit bacterial biofilms, and such biofilms may also be present in patients without peritonitis.