Detection of microbial DNA in the blood of surgical patients for diagnosing bacterial translocation

Abstract

Bacterial translocation sometimes occurs in patients during surgical stress and is associated with an increased incidence of septic morbidity. However, no reliable method has been established for diagnosing bacterial translocation in humans. Identification of minute quantities of microbial-specific DNA has been made possible using polymerase chain reaction (PCR) techniques. The aims of this study were to determine the prevalence of bacterial translocation in patients with surgical stress using PCR techniques and to evaluate the usefulness of blood PCR techniques for diagnosing bacterial translocation. DNA was extracted from the blood of 52 surgical patients (24 elective major surgery patients and 28 septic patients) and 10 healthy controls. PCR techniques were used to amplify genes from Escherichia coli, Bacteroides fragilis, a region of 16S ribosomal RNA found in many gram-positive and gram-negative bacteria, and Candida albicans. Bacterial and Candida albicans DNA were not detected in healthy volunteers. Enteric bacterial DNA was detected in patients with hepatic lobectomy, and Candida albicans DNA was detected in patients with esophagectomy on the first postoperative day. Enteric bacterial and Candida albicans DNA were detected in septic patients with findings diagnostic of bacterial translocation, such as small bowel obstruction, ulcerative colitis, or supramesenteric arterial occlusion or in those who had undergone chemotherapy for advanced colon cancer. However, none of the patients were positive by the blood culture technique. The PCR method is more sensitive than blood cultures for detecting bacterial components in the blood of septic patients and is a valuable tool for verifying bacterial translocation in patients who have undergone hepatic lobectomy or esophagectomy. It is also valuable in septic patients who do not have a defined focus of infection.