Probiotics Are Sensitive Microorganisms: Lactobacillus Can Be Affected by Stomach Acid, Antibiotic, and Bowel Cleansing

Abstract

We read with great interest the article by Mangell et al. entitled ‘‘Lactobacillus plantarum 299v does not reduce enteric bacteria or bacterial translocation in patients undergoing colon resection’’ [1]. The authors show that Lactobacillus plantarum 299v did not reduce enteric bacteria or bacterial translocation in patients undergoing colon resection. Although the study was well presented, there are some limitations and a few points on the affects of probiotics in the study protocol that we would like to address. Bowel cleansing before surgery can change the concentration of gut microbiota. Also, the patients had consumed food with L. plantarum 299v for 8 days in the preoperative period; however in the postoperative period, the patients had consumed L. plantarum 299v without food for 5 days. Foods typically contain fermentable substrates that can help nourish probiotic organisms as they transit through the gastrointestinal tract. Gastric pH following food intake is usually in the range of 4–7. Many lactobacilli and bifidobacteria secrete hydrolytic enzymes that can aid in the digestion of foods. Gastric pH is below 2 in the fasting state, which rapidly kills probiotics [2]. The main factors affecting the viability of probiotics in the gastrointestinal tract are the acidic environment of the stomach and the presence of bile in the duodenum. Significant numbers of probiotic bacteria can be destroyed unless they have some acid protection. Low pH is one of the most important factors that restricts the growth and stability of probiotic bacteria [3, 4]. Recent evidence shows that the dual-coating technology of probiotic bacteria enhances the survival and the amount of bacteria reaching the distal gut [5]. If there is an encapsulation technique of acid protection against L. plantarum 299v, it should be mentioned in this article. Preoperative and postoperative food intake might influence the transit of L. plantarum 299v to the distal gastrointestinal tractus. On the other hand, preoperative antibiotic prophylaxis may alter gut microbiota as well. The detection of bacterial genome in the lymph node does not reliably indicate recent bacterial translocation. Some bacteria might have already translocated in the preprobiotic phase, and scant amounts of these translocated bacteria might not be clinically important. Supporting this hypothesis, the authors did not mention any correlation with bacterial translocation and postoperative septic complications. And finally, two of these patients had translocation of lactobacilli, which is not a pathogenic bacterium. The rate of postoperative complications, although not significant between groups, is markedly decreased in the probiotic group. The overall complication rate, 16 versus 31 % (nearly twice as much in the control group), needs further comment. As a conclusion, probiotics are sensitive microbial agents to various noxious stimuli. Viability of probiotics in gastrointestinal tractus depends on some factors such as gastric acidity, bile acids, enzymes in intestine, antibiotics and bowel cleansing.