Detection of bacterial translocation by polymerase chain reaction in an experimental short bowel model

BACKGROUND: Bacterial overgrowth occuring after massive bowel resection, facilitates Gram-negative intestinal Bacterial Translocation (TB). Probiotic agents might have beneficial effects on TB. On the other hand, polymerase chain-reaction (PCR) has better sensitivity than conventional methods for bacterial detection and has not been investigated in experimental models of short bowel syndrome and TB. OBJECTIVE: To test the hypothesis that the administration of Bifidobacterium lactis (BL) decreases Escherichia coli Bacterial Translocation (ECTB) in experimental short bowel syndrome and to confirm the better sensitivity of PCR technique to detect ECTB. METHODS: Adult Wistar rats, orally fed with standard rat chow and tap water "ad libitum", were maintained in individual metabolic cages for ten days and divided into three groups: Control (n = 15): non-manipulated animals. RES (n = 15): 80% gut resection. Daily administration 1 ml of sterile water, after orogastric intubation. RES-PRO (n = 18): same resection and daily administration of 7.8 x10(9) Bifidobacterium lactis Colony Forming Units (CFU). At the end of the experiment, mesenteric lymph nodes (MLN), and both peripheral and portal blood samples were recovered and cultured by standard procedures. Also, genomic DNA from E. coli was detected by PCR technique. RESULTS: By conventional cultures ECTB was detected in 0% in the control group, 73% in the RES group and 33% in the RES-PRO group. PCR technique detected ECTB in 47% of the control group, 87% of the RES group and 33% of RES-PRO group, showing higher sensitivity. By both methods, animals receiving BL (RES-PRO group) showed less ECTB. By conventional culture, the relative risk (RR) was 0.45 (95% CI 0,22-0,79) and the number needed to treat (NNT) was 3 (95% CI 0-11). By PCR technique, the RR was 0.38 (95% CI 0.19-0.76), and the NNT 2 (95% CI 0-4). CONCLUSIONS: 1) Administration of Bifidobacterium lactis reduces the incidence of ECTB. 2) PCR technique is a more sensitive method for ECTB detection.