The effect on peritoneal dialysis pathogens of changing topical antibiotic prophylaxis

Prophylactic gentamicin 0.1% cream has demonstrated efficacy in preventing both exit-site infection (ESI) and peritonitis attributable to gram-positive and gram-negative organisms; however, the effect of this practice on the gentamicin susceptibility patterns of bacterial pathogens isolated from such infections is unknown. We therefore examined the effect of a change in our prophylactic topical antibiotic exit-site protocol (from mupirocin 2% cream to gentamicin 0.1% cream) on infection rates and susceptibility patterns.

This retrospective observational cohort study examined two periods of time: before and after the change in exit-site protocol. Each period was 30 months in duration, with a 2-month implementation period between, during which patient data were excluded. Demographic, clinical, and microbiology data were collected for each patient and episode of infection.

Overall, 377 patients were evaluated. In the mupirocin period (MUP), 145 infections occurred in 79 patients, and in the gentamicin period, 145 infections occurred in 93 patients. No significant effect was found either in overall episodes of infection (0.53 per year) or in episodes of peritonitis (0.429 vs 0.375 per year), but episodes of ESI increased significantly (0.098 vs 0.153 per year; p = 0.024; odds ratio: 1.55; 95% confidence interval: 1.05 to 2.28). Episodes of Staphylococcus aureus peritonitis increased by 38% (0.018 vs 0.025 per year), and episodes of S. aureus ESI increased significantly by 150% (0.022 vs 0.055 per year; p = 0.03; hazard ratio: 3.00; 95% confidence interval: 1.09 to 8.26). Episodes of pseudomonal peritonitis declined by 68% (0.022 vs 0.007 per year), and episodes of pseudomonal ESI increased by 150% (0.007 vs 0.018 per year). The gentamicin susceptibility for gram-positive isolates demonstrated no significant change; however, the gentamicin susceptibility for Enterobacteriaceae decreased by 12% and for Pseudomonas, by 14%.

The significant increase in episodes of ESI and the decrease in susceptibility for both Enterobacteriaceae and Pseudomonas isolates represent a concerning trend. Centers should examine trends in infection rates and in bacterial susceptibilities to determine the most appropriate agent for ESI prophylaxis.