Abstract: Objective  To explore the relationship between the levels of serum procalcitonin (PCT) and red blood cell distribution width (RDW) and the pathogen species in peritoneal dialysis-associated peritonitis (PDAP).  Methods  A total of 87 cases with PDAP treated in the Nephrology Department, the Second Affiliated Hospital of Anhui Medical University from January 2018 to January 2022 were retrospectively analyzed. According to the bacterial culture results of outflow dialysate, patients were divided into Gram-negative bacterial infection group (G- group, n=24) and Gram-positive bacterial infection group (G+ group, n=63). Clinical data and laboratory indexes were compared between the two groups. Logistic regression was used to analyze the risk factors for G- bacterial PDAP. ROC curve was used to assess the predictive value of serum PCT and RDW for G- bacterial PDAP.  Results  The predominant species was Staphylococcus epidermidis (36.51%) in the G+ group, and was Escherichia coli (41.67%) in the G- group. The number of nucleated cells (Z=-2.745, P=0.006) and percentage of multinucleated cells in the outflow dialysate (Z=-0.273, P=0.005), serum PCT (Z =-4.345, P＜0.001), serum C-reactive protein (Z=-2.859, P=0.004), RDW (Z=-2.908, P=0.004) and fibrinogen (t=-2.602, P=0.011) were significantly higher in G- group than in G+ group, while serum cholesterol (t=2.091, P=0.040) was significantly lower in G- group than in G+ group. Multivariate logistic regression demonstrated that higher serum PCT (OR=1.034, 95% CI 1.001~1.069, P=0.045) and higher RDW (OR=1.499, 95% CI 1.037~2.167, P=0.031) were the independent risk factors for G- bacterial PDAP. ROC curve showed that serum PCT combined with RDW had the greatest predictive value for the presence of G- bacterial PDAP, with the area under the curve of 0.815 (95% CI 0.717~0.890, P＜0.001).  Conclusion  Higher levels of serum PCT and RDW are the independent risk factors for G- bacterial PDAP. Serum PCT combined with RDW had a better predictive value for the presence of G- bacterial PDAP.

Key words: Procalcitonin, Red blood cell distribution width, Peritoneal dialysis-associated peritonitis, Pathogen species