Clinical Study On Intestinal Bacterial Translocation In Patients Undergoing Abdominal Operations

Objective: To detect blood bacterial DNA by polymerase chain reaction (PCR) in patients undergoing laparotomy, and discuss the relationship among PCR positive results, gut barrier dysfunction, intestinal bacterial translocation, postoperative systematic inflammatory response syndrome (SIRS) and infectious complications. Methods: Blood samples of 63 patients undergoing selective laparotomy were collected before and 2, 24, 48h after surgery. According to various criterions, the patients were divided into two categories respectively: major operations (duration>3h and/or blood loss>500ml) or less traumatic operations, GI (gastrointestinal) operations or non-GI operations, with postoperative SIRS or without SIRS. PCR was performed after DNA extraction and amplification, choosing -lactosidase gene of Escherichia coll (E. coli) and 16S rRNA gene of most pathogenic bacteria as target genes. Meanwhile, plasma levels of D-lactate and endotoxin in systemic circulation were examined. All patients were observed 30d for infectious complications. Results: (1) No bacterial DNA was detected before surgery, but it was positive in 12 patients (19.0%) postoperatively. (2) The positive rate of PCR at 2, 24 and 48h was 14.3%, 19.0% and 17.5% respectively (P>0.05). (3) The percentage of bacterial DNA presence in blood of patients undergoing GI or non-GI surgery was 20.6% (7/34) and 17.2% (5/29) respectively (P>0.05). (4) The percentage of bacterial DNA presence in patients undergoing major or less traumatic surgery was 36.0% (9/25) and 7.9% (3/38) (P<0.01). (5) Bacterial DNA was discovered in 41.7% (10/24) of SIRS patients and 5.1% (2/39) of non-SIRSpatients (P<0.01). 83.3% PCR-positive patients manifested SIRS, but only 27.5% of PCR-negative patients did so (P<0.01). (6) Eight patients developed postoperative infection in PCR positive group (66.67%), and none in PCR negative group. All infected cases were PCR positive. (7) The positive bacterial isolation rate of blood (4.8%, 3/63) was significantly lower than PCR positive rate (19.0%, 12/63) (P<0.01). (8) Positive detection of E. Coli DNA constituted 66.7% of the whole PCR positive results. (9) Plasma concentrations of D-lactate and endotoxin in PCR positive group were significantly higher than those in PCR negative group (P<0.01) , and there was a good correlation between D-lactate and LPS ( =0.91, P<0.01 ) . Conclusion: (1) Intestinal bacterial translocation may occur early (2h) after abdominal surgery. (2) E. Coli is the most important translocated bacteria. (3) Patients with positive PCR result were prone to develop SIRS and infection, suggesting a close relationship between BT and SIRS (as well as infection). (4) The presence of microbial DNA in blood was related to trauma severity, but not to GI tract involvement. (5) The good correlation among PCR positive results and elevated plasma levels of D-lactate and LPS indicated that increased intestinal permeability, caused by gut barrer function damage, led to bacterial and endotoxin translocation. (6) PCR technique is a sensitive and effective method for clinical bacterial translocation research.