Circulating bacterial-derived DNA fragments as a marker of systemic inflammation in peritoneal dialysis

Endotoxemia is common in peritoneal dialysis (PD) patients, and circulating lipopolysaccharide (LPS) level is related to the degree of systemic inflammation and atherosclerosis. We hypothesize that circulating bacterial DNA, another microbial component, correlates with the degree of systemic inflammation and predicts the survival of new PD patients.

We measured the plasma bacterial DNA level in the archive blood samples of 300 consecutive new PD patients. The result was compared with serum C-reactive protein (CRP) level, patient survival and peritonitis-free survival.

The average age was 57.8 ± 12.1 years, average plasma bacterial DNA level 34.3 ± 1.3 cycles and average follow-up 37.9 ± 22.2 months. The plasma bacterial DNA level correlated with serum CRP (r = 0.565, P < 0.001) and LPS levels (r = 0.224, P = 0.029). At 36 months, the patient survival were 77.5, 78.3, 74.6 and 65.2% for plasma bacterial DNA level quartiles I, II, III and IV, respectively (log-rank test, P = 0.034). By multivariate analysis with the Cox proportional hazard model to adjust for confounders, the plasma bacterial DNA level had no independent effect. Similarly, peritonitis-free survival were 60.6, 59.8, 60.3 and 50.4% for plasma bacterial DNA level quartiles I, II, III and IV, respectively, at 36 months (P = 0.020), and the difference was not significant after adjusting for confounding factors.

We found that the plasma bacterial DNA level correlated with the degree of systemic inflammatory state in PD patients. Although plasma bacterial DNA level seems to predict patient survival and peritonitis-free survival, the association disappears after adjusting for confounding factors. Further prospective studies are needed to delineate the role of plasma bacterial DNA as a prognostic marker of renal failure patients.