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Preoperative Probiotics Decrease Postoperative Infectious Complications of Colorectal Cancer

      Abstract

      Background

      The objective is to elucidate the effects of oral bifid triple viable probiotics among patients with colorectal cancer.

      Methods

      Sixty patients undergoing radical colorectal resection were randomly assigned to 3-day (days −5 to −3) preoperative probiotics (group A, n=30) or placebo (group B, n=30) treatment. The alteration of intestinal flora was evaluated by fecal cultures of Escherichia coli, Bifidobacterium longum and intestinal fungi; the gut barrier function by serum endotoxins and D-lactic acids and the immune and stress responses by peripheral blood immunoglobins, interleukin-6 and C-reactive protein. Postoperative infections were documented physically, radiologically and microbiologically.

      Results

      Inverted Bifidobacterium/Escherichia ratios were preoperatively and postoperatively present in group B (both P<0.05). Bifidobacterium counts increased significantly, whereas Escherichia counts decreased significantly on postoperative days 3 to 5 (P<0.05), along with reversing the Bifidobacterium/Escherichia ratio inversion until postoperative days 3 to 5 in group A. Group A also had lower levels of endotoxins, D-lactic acids, serum interleukin-6 and C-reactive protein but higher levels of serum IgG and sIgA (all P<0.05) than group B. The incidences of postoperative infectious complications were 3.3% to 6.7% and 3.3% to 30% in groups A and B (overall, 10.0% versus 33.3%, P<0.05), respectively.

      Conclusion

      The preoperative oral bifid triple viable probiotics minimize the postoperative occurrence of infectious complications, with possible mechanisms attributed to the maintenance of the intestinal flora and restriction of bacterial translocation from the intestine. It was representative of the enhancement of systemic/localized immunity and concurrent attenuation of systemic stress response.

      Key Indexing Terms

      Colorectal cancer (CRC) is the second leading cause of adult cancer deaths in the United States.
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      their use remains controversial.
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      • Morelli L.
      • Galbiati F.
      • et al.
      A randomized double-blind trial on perioperative administration of probiotics in colorectal cancer patients.
      found that preoperative administration of a mixture of Lactobacillus johnsonii (La) and B longum (BB536) to patients with CRC undergoing colorectal resection affected intestinal microbiota by reducing the concentration of pathogens and modulating local immune responses, but they did not study its impacts on clinical parameters, such as gut barrier function, systemic immune responses and postoperative infectious morbidities.
      The objective of this study was to elucidate the effects of probiotic supplementation on postoperative intestinal flora profiles, gut barrier function and systemic immune responses among patients with CRC undergoing elective radical surgeries. The patients received oral bifid triple viable probiotics or a placebo as a supplement to preoperative bowel preparation in a randomized double-blind clinical setting. The study aimed to justify the use of preoperative oral probiotics for the minimization of postoperative infections and related complications.

      MATERIALS AND METHODS

      Patient Enrollment

      This study was a single-center prospective randomized control study. The study protocol was approved by the Institutional Review Board at Xin-Hua Hospital, Shanghai Jiaotong University. Eligible patients (n=82) were consecutively enrolled between August 2006 and June 2007, aged 45 to 90 years. A patient was included if he or she had been diagnosed with pathologically documented colorectal adenocarcinoma and intended to undergo elective radical CRC resection with laparotomy at Xin-Hua Hospital. No patient had received neoadjuvant chemotherapy or radiotherapy before the resection. Patients were excluded from the study if they were unavailable for the collection of fecal samples 6 days before operation (n=5); if the radical resection failed or the CRC was complicated with malignant ascites (n=4); if they exhibited moderate to severe cardiac, pulmonary, hepatic or renal dysfunction (n=4); if they had a preexisting autoimmune disease (n=2); if they were afflicted with an infectious disease within the 30 days preceding the enrollment (n=4) or if they had participated in any other clinical trial within the last 6 months (n=3). All participants volunteered to give informed consent. The eligible patients (n=60) were randomized and divided into 2 treatment groups: group A (n=30) received preoperative probiotics and group B (n=30) received placebos.

      Treatment

      The probiotic and placebo treatments were identically sealed with aluminum foil and administered in a double-blind manner for 3 days (days −5 to −3) before surgery. The patients in group A received 3 oral bifid triple viable capsules, each of which contained 0.21 g (108 cfu/g) of B longum, L acidophilus and Enterococcus faecalis (Shanghai Sine Wangxiang Pharmaceutical Co., Shanghai, China), 3 times a day, whereas the control patients in group B also received 3 placebo capsules containing maltodextrin three times a day. Conventional bowel preparation was performed on preoperative day 2 afterward (days −2 and −1), including the administration of a full liquid diet, oral gentamicin (80,000 U, three times a day; Zhongxi Pharm Co., Shanghai, China), metronidazole (0.4 g, 3 times a day; Sine Wanxiang Pharmaceutical Co.), polyethylene glycol (139.12 g/2,000 mL, every day; Jiangxi Hygecon Pharmaceutical Co., Shangrao, China) and a daily intravenous infusion of 1,000 mL crystal fluid. During surgery, 3 g of cefuroxime sodium (Zhijun Pharmaceutical Co., Shenzhen, China) was administered intravenously under general anesthesia. A postoperative prophylactic regimen of 3 g of cefuroxime sodium and 1 g of metronidazole (Baxter Healthcare Co., Shanghai, China) was intravenously infused twice daily for 3 to 5 days. All the patients received parenteral nutrition from days +1 to +5 and resumed oral intake after the occurrence of the first spontaneous anal passage of gas or feces (days +3–+5).

      Fecal Assay

      Fresh fecal samples (0.5 g) were collected on preoperative days 6 (day −6) and 3 (day −3) and from the first spontaneous postoperative defecation (postoperative days 3–5, days +3–+5). The samples were dissolved in 4.5 mL of normal saline. The suspensions were homogenized for 3 minutes in a stomacher (PBI, Milan, Italy), followed by continuous 10-fold dilution. The diluted suspensions were inoculated in an aerobic environment onto MacConkey agar plates (Oxoid, Cambridge, United Kingdom) at 37°C for 24 hours for the culture and count of E coli, onto modified Sabouraud’s agar plates containing 30 μg/mL of imipenem (bioMérieux, Marcy l’Etoile, France) at 20°C to 25°C for 5 to 7 days for the culture and count of fungi and onto Genbox anaer (bioMérieux) at 37°C for 48 hours for the culture in an aerobical environment and count of B longum. Available plates were harvested to obtain counts of colony-forming units, which were converted into the number of bacteria per gram.

      Peripheral Blood Assay

      Peripheral venous blood samples were taken on preoperative days 6 (day −6), 3 (day −3) and 1 (day −1) and postoperative days 1 (day +1), 3 (day +3) and 9 (day +9). Sera were isolated for IgG, IgM, IgA, sIgA, interleukin-6 (IL-6), C-reactive protein (CRP) and D-lactic acid assays using commercially available enzyme-linked immunosorbent assay kits (IgG, IgM, IgA: Zeptometrix, Buffalo, NY; IL-6: Thermo Scientific, Surrey, United Kingdom; D-lactic acid: Roche-Biopharm, Darmstadt, Germany; CRP: RayBiotech, Norcross, GA and sIgA: Shanghai TJFM Co., Shanghai, China). Endotoxins were quantified with a limulus amebocyte lysate assay kit (Yihua Bio, Shanghai, China). Blood cultures were also obtained in cases of pyrexia exceeding 38.5°C at any time postoperatively, regardless of the presence or absence of an infectious source. Whole blood (10 mL) was sterilely drawn from each set of blood cultures and immediately inoculated into separate blood-culture bottles (Organon Teknika, Durham, NC) for aerobic and anaerobic identification, for 7 days or until the detection of bacterial growth. The diagnosis of bacteremia was confirmed with the isolation of any live organism in a single blood culture, unless the isolate was determined to be Staphylococcus epidermidis or any other coagulase-negative Staphylococcus species. In such cases, blood cultures were repeated to exclude contamination by coagulase-negative Staphylococci.

      Observation of Postoperative Infectious Complications

      Detailed daily records of postoperative courses were maintained for each patient. Postoperative infections included bacteremia and/or septicemia, postprocedural pneumonias, intra-abdominal abscesses, surgical site infections, perineal infections and anastomotic leakage or fistulae. Bacteremia was defined as the presence of viable bacteria in the blood and was diagnosed by blood culture. Postoperative septicemia was recorded prospectively for all patients until their discharge from our hospital. Postprocedural pneumonia referred to the radiographic presence of characteristic pulmonary infiltration complicated with leukocytosis. Intra-abdominal abscess was characterized by purulent discharge from intraoperatively placed peritoneal drains or the peritoneal accumulation of infectious fluids requiring drainage (confirmed by positive cultures). Surgical site infection referred to spontaneous or surgically released purulent discharge, confirmed by positive cultures. Perineal infection was characterized by an abscessed perineal wound that discharged spontaneously or required surgical draining. Anastomotic leakage designated a symptomatic leak that was verified by a water-soluble contrast enema, endoscopic examination, the presence of any palpable defect and/or the discharge of fecal material from the drain. Patients with postoperative infectious complications received a combined intravenous regimen of 3 g of cefuroxime sodium and 1 g of metronidazole (twice daily) until the infection was effectively controlled.

      Statistical Analysis

      All quantitative data were expressed as mean±standard deviation. Differences in the means of groups A and B were compared using repeated-measures analysis in a general linear model. For each time point, the intragroup comparison was performed using the paired Student’s t test, and intergroup comparison was performed using the independent 2-sample Student’s t test. The qualitative data were expressed as percentages and were compared with the χ2 or Fisher’s exact test. A P value <0.05 was considered to be statistically significant.

      RESULTS

      Patient Characteristics

      Eighty-two patients were included in this study and 22 were excluded. Sixty patients were randomly assigned to either of the 2 treatment arms. No differences were observed between groups A and B in baseline characteristics, including age, sex, body mass index, hemoglobin value, peripheral white blood cell count, tumor site, procedure received, operating time, colostomy (for Mile’s), defunctioning ileostomy, cancer stage, pathological feature and length of hospital stay (Table 1).
      Table 1Baseline characteristics of colorectal cancer patients (n=60)
      Group A (n=30)Group B (n=30)P
      Data were analyzed using Student’s t test or Pearson’s χ2 test.
      Age [yr, median (range)]67.5 (45.0–87.0)61.5 (46.0–82.0)0.079
      Sex (male:female, n)10:2014:160.192
      BMI (kg/m2, mean±SD)24.4±2.125.1±2.50.266
      Hemoglobin (g/L, mean±SD)123.3±12.2124.5±10.80.663
      WBC count (per mm3)6.6±1.76.8±1.40.486
      Site of tumor and procedure received0.923
       Ascending colon and right hemicolectomy13/3011/30
       Descending colon and left hemicolectomy6/309/30
       Sigmoid colon and sigmoid colectomy4/304/30
       Rectum and anterior resection4/303/30
       Abdominopernieal excision3/303/30
      Operating time (min, mean±SD)118±25122±270.584
      Colostomy (for Mile’s)331.000
      Defunctioning ileostomy00
      Cancer stage0.904
       I43
       II1818
       III89
       IV00
      Pathological features0.933
       Papillary32
       Tubular1720
       Papillary and tubular64
       Mucus33
       Undifferentiated11
      Length of hospital stay (day, mean±SD)12±314±30.109
      Group A, bifid triple viable probiotics treatment group; group B, placebo treatment group; BMI, body mass index; SD, standard deviation; WBC, white blood cell.
      a Data were analyzed using Student’s t test or Pearson’s χ2 test.

      Fecal Bacterial Colonies

      On preoperative day 6 (day −6), the E coli and B longum counts of groups A and B were similar, and the B/E ratios of both groups were inverted (below 1.0). However, after 2 days of preoperative treatment, the E coli count was slightly decreased in group A on preoperative day 3 (day −3), and the B longum count was significantly increased (day −6 versus day −3, 8.29±0.10 log10/g versus 9.29±0.23 log10/g, P<0.001; group A versus group B, 9.29±0.23 log10/g versus 8.26±0.13 log10/g, P<0.001), indicating the reversal of the B/E ratio inversion (day −6 versus day −3, −0.26±0.32 versus 1.26±0.28, P<0.001; group A versus group B, 1.26±0.28 versus −0.27±0.34, P<0.001). Although the postoperative B longum counts were significantly reduced in both groups, as documented by the first spontaneous fecal sample (days +3–+5) assays, the E coli count was significantly higher in group B (group A versus group B, 8.29±0.27 log10/g versus 9.67±0.17 log10/g, P<0.001), and the B longum count was significantly higher in group A (group A versus group B, 8.43±0.17 log10/g versus 7.94±0.11 log10/g, P<0.001). These values indicated that a significant positive value of the B/E ratio still sustained in group A, whereas a more pronounced B/E ratio inversion occurred in group B postoperatively (Figure 1) (day −6 versus days +3–+5, 0.14±0.20 versus −0.26±0.32, P<0.001; group A versus group B, 0.14±0.20 versus −1.73±0.22, P<0.001). The fungal counts in the fecal samples remained stable in both groups throughout the study period (all P>0.05).
      Figure thumbnail gr1
      Figure 1Diachronic trends of fecal E coli (A) and B longum (B) counts and Bifidobacterium/Escherichia ratio (C) from preoperative day 6 through the first spontaneous postoperative defecation. (a) Repeated-measures analysis within a general linear model; (b) paired Student’s t test, P<0.05 versus preoperative day 6; (c) independent 2-sample Student’s t test, P<0.05 versus placebo treatment group. Day −6, preoperative day 6; day −3, preoperative day 3; days +3–+5, the time point of the first spontaneous postoperative defecation.

      Bacterial Translocation From the Intestine

      As shown in Figure 2, endotoxin and D-lactic acid serum levels were similar between the 2 groups on preoperative days 6 (day −6) and 3 (day −3). The level of endotoxin increased significantly in group B on postoperative day 3 (day +3) (day −6 versus day +3, 0.027±0.002 EU/mL versus 0.085±0.005 EU/mL, P<0.001; group A versus group B, 0.025±0.005 EU/mL versus 0.085±0.005 EU/mL, P<0.001), as well as the levels of D-lactic acid in group B on postoperative day 3 (day +3) (day −6 versus day +3, 3.22±0.18 mg/L versus 3.93±0.22 mg/L, P<0.001; group A versus group B, 3.29±0.16 mg/L versus 3.93±0.22 mg/L, P<0.001), suggesting the translocation of bacteria from the intestine. In contrast, these biochemical measures did not change significantly in group A from preoperative to postoperative periods: the endotoxin level remained at a significantly lower level on day −3 (group A versus group B, 0.021±0.003 EU/mL versus 0.027±0.003 EU/mL, P<0.001) and day +3 (group A versus group B, 0.025±0.005 EU/mL versus 0.085±0.005 EU/mL, P<0.001), whereas the D-lactic acid level also stayed at a significantly lower level on day +3 (group A versus group B, 3.29±0.16 mg/L versus 3.93±0.22 mg/L, P<0.001). Only E coli was identified in aerobic peripheral blood cultures, whereas no microbe was isolated from anaerobic cultures. The detection rate of E coli was rare in the 2 groups on preoperative day 3 (day −3) and postoperative day 3 (day +3). However, the rate was significantly higher in group B than in group A (group A versus group B, 3.3% versus 26.7%, P=0.026).
      Figure thumbnail gr2
      Figure 2Diachronic trends of serum endotoxin (A) and D-lactic acid (B) levels from preoperative day 6 through postoperative day 3. (a) Repeated-measures analysis within a general linear model; (b) paired Student’s t test, P<0.05 versus preoperative day 6; (c) independent 2-sample Student’s t test, P<0.05 versus placebo treatment group. Day −6, preoperative day 6; day −3, preoperative day 3; day +3, postoperative day 3.

      Immune and Inflammatory Responses

      As shown in Figure 3, the serum IgG level in group B declined significantly between preoperative day 1 (day −1) and postoperative day 9 (day +9) (day −1 versus day +9, 10.45±2.11 g/L versus 7.85±1.83 g/L, P<0.001), whereas that in group A remained relatively stable during the same time period. The serum IgG level in group A was significantly higher than that in group B on postoperative day 9 (day +9) (group A versus group B, 10.88±2.22 g/L versus 7.85±1.83 g/L, P<0.001). The diachronic trends of serum sIgA levels were comparable with those of serum IgG for both groups, except that serum sIgA declined significantly in both groups on postoperative day 1 (day +1) compared with preoperative day 1 (day −1) (group A, day −1 versus day +9, 0.66±0.13 g/L versus 1.29±0.22 g/L, P<0.001; group B, day −1 versus day +9, 0.62±0.13 g/L versus 1.18±0.19 g/L, P<0.001). IgM and IgA levels did not differ significantly between groups in the preoperative or postoperative periods.
      Figure thumbnail gr3
      Figure 3Diachronic trends of serum IgG (A), IgM (B), IgA (C), sIgA (D), interleukin-6 (E) and C-reactive protein (F) levels from preoperative day 1 to postoperative day 9. Group A, bifid triple viable probiotics treatment group; group B, placebo treatment group; IL, interleukin; CRP, C-reactive protein. (a) Repeated-measures analysis within a general linear model; (b) paired Student’s t test, P<0.05 versus preoperative day 1; (c) independent 2-sample Student’s t test, P<0.05 versus placebo treatment group. Day −1, preoperative day 1; day +1, postoperative day 1; day +3, postoperative day 3.
      The serum level of IL-6 was significantly higher than preoperative levels in group B on postoperative day 1 (day +1) and day 9 (day +9) (day −1 versus day +1, 137.24±44.76 pg/mL versus 198.33±47.49 pg/mL, P<0.001; day −1 versus day +9, 137.24±44.76 pg/mL versus 178.43±40.16 pg/mL, P<0.001). IL-6 in group A exhibited a significant increase on postoperative day 1 (day +1) (day −1 versus day +1, 138.41±42.57 pg/mL versus 182.99±47.73 pg/mL, P<0.001) but returned to the normal level on postoperative day 9 (day +9) (day −1 versus day +9, 138.41±42.57 pg/mL versus 155.46±39.71 pg/mL, P=0.1). Postoperative IL-6 levels in peripheral blood were lower in group A than in group B on postoperative day 9 (day +9) (group A versus group B, 155.46±39.71 pg/mL versus 178.43±40.16 pg/mL, P<0.001). The diachronic trends of serum CRP in both groups were similar to those of peripheral blood IL-6, except that serum CRP levels did not return to the normal level on postoperative day 9 (day +9) in group A (day −1 versus day +9, 5.63±2.02 pg/mL versus 19.44±2.43 pg/mL, P<0.001).

      Postoperative Infectious Morbidities and Other Complications

      Within 9 days after the radical surgery, postoperative infections occurred in 13 patients (Table 2). The incidences of postoperative infectious complications were 3.3% to 6.7% and 3.3% to 30% in groups A and B (overall, 10.0% versus 33.3%, P=0.028), respectively. Symptomatic intestinal obstructions were identified in both groups (A, 3/30; B, 6/30), manifesting as abdominal distention, abdominal pain and emesis. All these patients recovered with symptomatic treatment. The duration of hospitalization did not differ between groups. No mortality occurred in either group.
      Table 2Postoperative infections and other procedure-related complications (n, %) of colorectal cancer patients (n=60) by treatment group
      Group A (n=30)Group B (n=30)P
      Bacteremia2 (6.7)9 (30.0)0.020
      Pearson’s χ2 test.
      Septicemia1 (3.3)8 (26.7)0.027
      Fisher’s exact probability test.
      PPPs1 (3.3)4 (13.33)0.353
      Fisher’s exact probability test.
      IAAs2 (6.7)1 (3.3)1.000
      Fisher’s exact probability test.
      SSIs1 (3.3)4 (13.3)0.353
      Fisher’s exact probability test.
      Perineal infection1 (3.3)2 (6.7)1.000
      Fisher’s exact probability test.
      Anastomotic leak0 (0.0)2 (3.3)0.492
      Fisher’s exact probability test.
      Total3 (10.0)10 (33.3)0.028
      Pearson’s χ2 test.
      Group A, bifid triple viable probiotics treatment group; group B, placebo treatment group; PPPs, postprocedural pneumonias; IAAs, intra-abdominal abscesses; SSIs, surgical site infections.
      a Pearson’s χ2 test.
      b Fisher’s exact probability test.

      DISCUSSION

      Several previous studies have suggested that appropriate preoperative regimens of probiotics play an active role in the prevention of postoperative infectious complications after abdominal or gastrointestinal procedures.
      • Sugawara G.
      • Nagino M.
      • Nishio H.
      • et al.
      Perioperative synbiotic treatment to prevent postoperative infectious complications in biliary cancer surgery: a randomized controlled trial.
      • Kinross J.
      • Warren O.
      • Silk D.
      • et al.
      Perioperative synbiotic treatment to prevent postoperative infectious complications in biliary cancer surgery: a randomized control trial.
      • Reddy B.S.
      • Macfie J.
      • Gatt M.
      • et al.
      Randomized clinical trial of effect of synbiotics, neomycin and mechanical bowel preparation on intestinal barrier function in patients undergoing colectomy.
      • Ohishi A.
      • Takahashi S.
      • Ito Y.
      • et al.
      Bifidobacterium septicemia associated with postoperative probiotic therapy in a neonate with omphalocele.
      Gianotti et al
      • Gianotti L.
      • Morelli L.
      • Galbiati F.
      • et al.
      A randomized double-blind trial on perioperative administration of probiotics in colorectal cancer patients.
      administered a preoperative probiotic mixture of L johnsonii and B longum to a patient population that was similar to that of this study. They detected surviving L johnsonii in a dose-dependent manner among intraoperatively collected intestinal mucosal specimens and postoperatively collected fecal samples. They also found that cellular immunity was enhanced by oral probiotic treatment, in contrast to placebo treatment.
      • Gianotti L.
      • Morelli L.
      • Galbiati F.
      • et al.
      A randomized double-blind trial on perioperative administration of probiotics in colorectal cancer patients.
      Our study further examined the changes in intestinal flora using bacterial cultures, bacterial translocation from the intestine using serum endotoxins and D-lactic acids, systemic and regional immunities using IgG/IgM/IgA and sIgA assays, systemic stress response using serum IL-6 and CRP assays and the incidence of postoperative infectious complications. Some previous studies involved the assessment of the effect of perioperative probiotic treatment in CRC surgery.
      • Gianotti L.
      • Morelli L.
      • Galbiati F.
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      A randomized double-blind trial on perioperative administration of probiotics in colorectal cancer patients.
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      Randomised clinical trial: the effects of perioperative probiotic treatment on barrier function and post-operative infectious complications in colorectal cancer surgery—a double-blind study.
      To the best of our knowledge, however, this prospective, randomized, controlled, double-blind study was the first study performed among patients with CRC undergoing radical surgery in a tertiary academic healthcare setting to comprehensively examine objective outcomes, including microbiological, physiological and immunological effects of bifid triple viable probiotics regimen.
      Probiotics vary in species and strains and are microbiologically activated through various mechanisms. Each probiotic strain has been characterized by its gastrointestinal survivability, modulation of intestinal flora and immune activities.
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      Probiotics, prebiotics, and synbiotics.
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      Perioperative synbiotic treatment to prevent infectious complications in patients after elective living donor liver transplantation: a prospective randomized study.
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      Does the use of probiotics/synbiotics prevent postoperative infections in patients undergoing abdominal surgery? A meta-analysis of randomized controlled trials.
      • Zuccotti G.V.
      • Meneghin F.
      • Raimondi C.
      • et al.
      Probiotics in clinical practice: an overview.
      The 3 strains used in our study have been widely used in nutritional and clinical practice. As an aerobe, E faecalis is located primarily in the upper gastrointestinal tract. L acidophilus is a facultative anaerobe located in the middle segment, and B longum is an anaerobe located in the lower tract.
      • Lee Y.K.
      • Nomoto K.
      • Salminen S.
      • et al.
      B longum and L acidophilus are strongly resistant to gastric and bile acids, showing 2-hour survival rates of 70% and 60% in the presence of gastric acids, respectively. In addition, both species exhibit 2-hour survival rates exceeding 80% in the presence of bile acids.
      • Marteau P.
      • Minekus M.
      • Havenaar R.
      • et al.
      Survival of lactic acid bacteria in a dynamic model of the stomach and small intestine: validation and the effects of bile.
      • Massi M.
      • Vitali B.
      • Federici F.
      • et al.
      Identification method based on PCR combined with automated ribotyping for tracking probiotic Lactobacillus strains colonizing the human gut and vagina.
      • O’Sullivan D.J.
      • Kullen M.J.
      Tracking of probiotic bifidobacteria in the intestine.
      • Vaughan E.E.
      • Heilig H.G.
      • Ben-Amor K.
      • et al.
      Diversity, vitality and activities of intestinal lactic acid bacteria and bifidobacteria assessed by molecular approaches.
      Most oral triple probiotics reach and colonize the small and large intestines in active forms, competing with intestinal pathogenic microorganisms for epithelial adhesion sites through an occupying mechanism. These probiotics restore the balance of gut flora because the preoperative liquid diet is retained in the stomach for only 1 to 2 hours and is not retained at all in the small intestine.
      • O’Sullivan D.J.
      • Kullen M.J.
      Tracking of probiotic bifidobacteria in the intestine.
      • Fedorak R.N.
      • Madsen K.L.
      Probiotics and prebiotics in gastrointestinal disorders.
      Probiotic metabolites are capable of nourishing and potentiating the intestinal mucosal barrier and immune functions.
      • Duggan C.
      • Gannon J.
      • Walker W.A.
      Protective nutrients and functional foods for the gastrointestinal tract.
      The intestinal bacteria living within the lumen affect the host homoeostasis; some of these bacteria are potential pathogens and currently presumed to be the major source of infectious complications secondary to gastrointestinal procedures.
      • Guarner F.
      • Malagelada J.R.
      Gut flora in health and disease.
      This suggests that the interaction between host and intestinal microorganisms is thought to be present at the following 3 levels. First, in the intestinal lumen, the microbiota functions to digest food components, maintain microbial colonization resistance and prevent the colonization of pathogenic bacteria. Second, the mucosal barrier consisting of intestinal epithelial lining protects the interior milieu of the host from the invasion of pathogens. Microorganisms are responsible for local gene regulation in intestinal epithelia, thereby strengthening the mucosal barrier. The epithelia in turn provide an energy source for certain bacteria. The microbiota exerts a local anti-inflammatory effect through the cross talk with local immune cells, avoiding uncontrolled mucosal inflammation. Third, the immune system is also affected by the intestinal microbiota. Dendritic cells pry open tight junctions of epithelial cells to sample luminal content and take up bacteria. This continuous cross talk between microbiota and immune system leads to the induction of B and T cells with potential systemic immune responses.
      • van Santvoort H.C.
      • Besselink M.G.
      • Timmerman H.M.
      • et al.
      Probiotics in surgery.
      • Hooper L.V.
      • Gordon J.I.
      Commensal host-bacterial relationships in the gut.
      Our oral triple probiotics regimen not only inhibited the intestinal overgrowth of E coli but also reversed the originally inverted B/E ratio. This outcome suggested the microbial colonization resistance of host intestinal lumen,
      • Si J.M.
      • Yu Y.C.
      • Fan Y.J.
      • et al.
      Intestinal microecology and quality of life in irritable bowel syndrome patients.
      • Wu Z.
      • Li L.
      • Ma W.
      • et al.
      [Study on the intestinal microbial colonization resistance in patients with chronic severe hepatitis].
      evidencing its role of inhibition of pathogenic bacteria of intestinal flora invading host at the lumenal level. Endotoxins and D-lactic acids derived from intestinal microorganisms also remained at relatively low levels, indicating that the regimen might have restricted bacterial translocation from the intestine through the mucosal barrier. In addition, intestinal sIgA and IgG levels remained relatively normal, suggesting the immunopotent properties of the regimen. This oral bifid triple viable probiotic regimen effectively attenuated the stress response, as documented by serum IL-6 and CRP levels, and reduced the risk of postoperative infections, as assessed with clinical and microbiological measures.
      In summary, our findings justified the use of a preoperative oral bifid triple viable probiotic regimen. The preoperative oral bifid triple viable probiotics could minimize the postoperative occurrence of infectious complications possibly because of their inhibitory effects on intestinal overgrowth of E coli. Moreover, the probiotics maintained microbial colonization resistance and restricted bacterial translocation from the intestine. It was the representative of the enhancement of systemic/localized immunity and concurrent attenuation of systemic stress response.

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