Residual of bacterial DNA in hemodialyzers: the proof of subclinical infection sustaining chronic inflammation.
OBJECTIVE
Inflammation and infection seem to be important causes of morbidity and mortality in Chronic Kidney Disease (CKD) patients. Subclinical infections have been proposed as an important cause of inflammatory syndrome but to date this hypothesis remains speculative. In this investigation, we developed a method for molecular detection of the presence of bacterial DNA in a population of chronic kidney disease patients in order to correlate molecular data with the degree and level of inflammation and to evaluate the usefulness of the method in the diagnosis of subclinical infection.


METHODS
The study was divided into two phases: the study of a population of 81 CKD patients for prevalence and level of inflammation and infection; and the molecular evaluation of a subgroup of 38 patients without evident clinical causes of inflammation for molecular evaluation of subclinical infection.


RESULTS
Patients hemoculture negative turned out positive for the presence of bacterial DNA when molecular methods were used. We found a trend of correlation with the presence of bacterial DNA and the increase in hs-CRP, IL-6 and oxidative stress (AOPP) levels and a reduction in MFI DR+. Hemodialyzer membranes seem to have properties that are 'sticky' to bacteria/bacterial DNA and work as concentrators. Moreover our data suggest that DNA can traverse hemodialysis membranes.


CONCLUSIONS
Molecular methods have turned out to be far more sensitive than standard methods in detecting subclinical infection. The presence of bacterial DNA seems to influence the variation of some parameters of inflammation and immunity. Apart from the limitations and pitfalls, a molecular method could be useful for the screening of subclinical infection and diagnosis of sepsis when the hemoculture is negative. The identification of the microorganism involved, however, must be done with species-specific primers. These results are preliminary and more investigations will have to be performed in order to confirm our results.
De Cal
M
M
Department of Nephrology, San Bortolo Hospital, International Renal Research Institute Vicenza (IRRIV), Vicenza - Italy.
Cazzavillan
S
S
Rassu
M
M
Ronco
C
C
D001424:Bacterial Infections / Q000097:blood / Q000175:diagnosis; D002097:C-Reactive Protein / Q000032:analysis; D015331:Cohort Studies; D004269:DNA, Bacterial / Q000097:blood*; D006801:Humans; D007249:Inflammation / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000276:immunology*; D006435:Renal Dialysis; D012709:Serum Albumin / Q000032:analysis
D004269:DNA, Bacterial; D015850:Interleukin-6; D012709:Serum Albumin; D002097:C-Reactive Protein