Usefulness of a molecular strategy for the detection of bacterial DNA in patients with severe sepsis undergoing continuous renal replacement therapy

Area of Science:

• Microbiology
• Critical Care Medicine
• Molecular Diagnostics

Background:

• Sepsis is a leading cause of death in critically ill patients, often involving cell death and the release of circulating DNA.
• Plasma DNA can originate from host cells or bacteria, making its detection relevant in sepsis diagnosis.
• Existing diagnostic methods like blood culture have limitations in sensitivity and speed.

Purpose of the Study:

• To validate a method for detecting bacterial DNA in critically ill patients with severe sepsis.
• To compare the diagnostic efficacy of bacterial DNA detection with standard blood cultures.
• To assess bacterial DNA presence in blood, hemofilters, and ultrafiltrate during continuous renal replacement therapy (CRRT).

Main Methods:

• Analysis of bacterial DNA in blood, hemofilters, and ultrafiltrate using polymerase chain reaction (PCR) amplification of the 16S rRNA gene.
• Inclusion of 9 critically ill patients diagnosed with severe sepsis and acute renal failure requiring CRRT.
• Comparison with standard blood culture results for all participating patients.

Main Results:

• Bacterial DNA was detected in the blood of 67% of patients, significantly higher than the 22% positive blood culture rate.
• Bacterial DNA was identified in 100% of hemofilters (blood side) and 78% in the dialysate compartment.
• No bacterial DNA was detected in the ultrafiltrate, suggesting adsorption to the filter material.

Conclusions:

• Detection of bacterial DNA via 16S rRNA gene sequencing is a valuable screening tool for sepsis, particularly in blood culture-negative patients on CRRT.
• The technique shows higher sensitivity than blood cultures for identifying bacterial presence in septic patients.
• While useful for screening, this method does not identify specific pathogenic organisms, requiring further targeted identification.