Oxalate consumption by lactobacilli: evaluation of oxalyl-CoA decarboxylase and formyl-CoA transferase activity in Lactobacillus acidophilus.

AIMS: This study was undertaken to evaluate the oxalate-degrading activity in several Lactobacillus species widely used in probiotic dairy and pharmaceutical preparations. Functional characterization of oxalyl-CoA decarboxylase and formyl-CoA transferase in Lactobacillus acidophilus was performed in order to assess the possible contribution of Lactobacillus in regulating the intestinal oxalate homeostasis. METHODS AND RESULTS: In order to determine the oxalate-degrading ability in 60 Lactobacillus strains belonging to 12 species, a screening was carried out by using an enzymatic assay. A high variability in the oxalate-degrading capacity was found in the different species. Strains of Lact. acidophilus and Lactobacillus gasseri showed the highest oxalate-degrading activity. Oxalyl-CoA decarboxylase and formyl-CoA transferase genes from Lact. acidophilus LA14 were cloned and sequenced. The activity of the recombinant enzymes was assessed by capillary electrophoresis. CONCLUSIONS: Strains of Lactobacillus with a high oxalate-degrading activity were identified. The function and significance of Lact. acidophilus LA14 oxalyl-CoA decarboxylase and formyl-CoA transferase in oxalate catabolism were demonstrated. These results suggest the potential use of Lactobacillus strains for the degradation of oxalate in the human gut. SIGNIFICANCE AND IMPACT OF THE STUDY: Identification of probiotic strains with oxalate-degrading activity can offer the opportunity to provide this capacity to individuals suffering from an increased body burden of oxalate and oxalate-associated disorders.

Characterization and selection of vaginal Lactobacillus strains for the preparation of vaginal tablets.

AIMS: To characterize and select Lactobacillus strains for properties that would make them a good alternative to the use of antibiotics to treat human vaginal infections. METHODS AND RESULTS: Ten Lactobacillus strains belonging to four different Lactobacillus species were analysed for properties relating to mucosal colonization or microbial antagonism (adhesion to human epithelial cells, hydrogen peroxide production, antimicrobial activity towards Gardnerella vaginalis and Candida albicans and coaggregation with pathogens). The involvement of electrostatic interactions and the influence of bacterial metabolic state in the binding of lactobacilli to the cell surface were also studied. Adherence to epithelial cells varied greatly among the Lactobacillus species and among different strains belonging to the same Lactobacillus species. The reduction in surface negative electric charge promoted the binding of several Lactobacillus strains to the cell membrane whereas lyophilization reduced the adhesion capacity of many isolates. The antimicrobial activity of lactobacilli culture supernatant fluids was not directly related to the production of H2O2. CONCLUSIONS: Three strains (Lactobacillus brevis CD2, Lact. salivarius FV2 and Lact. gasseri MB335) showed optimal properties and were, therefore, selected for the preparation of vaginal tablets. The selected strains adhered to epithelial cells displacing vaginal pathogens; they produced high levels of H2O2, coaggregated with pathogens and inhibited the growth of G. vaginalis. SIGNIFICANCE AND IMPACT OF THE STUDY: The dosage formulation developed in this study appears to be a good candidate for the probiotic prophylaxis and treatment of human vaginal infections.

Reduction of oxaluria after an oral course of lactic acid bacteria at high concentration.

BACKGROUND: Hyperoxaluria is a major risk factor for renal stones, and in most cases, it appears to be sustained by increased dietary load or increased intestinal absorption. Previous studies have shown that components of the endogenous digestive microflora, in particular Oxalobacter formigenes, utilize oxalate in the gut, thus limiting its absorption. We tested the hypothesis of whether oxaluria can be reduced by means of reducing intestinal absorption through feeding a mixture of freeze-dried lactic acid bacteria. METHODS: Six patients with idiopathic calcium-oxalate urolithiasis and mild hyperoxaluria (>40 mg/24 h) received daily a mixture containing 8 x 10(11) freeze-dried lactic acid bacteria (L. acidophilus, L. plantarum, L. brevis, S. thermophilus, B. infantis) for four weeks. The 24-hour urinary excretion of oxalate was determined at the end of the study period and then one month after ending the treatment. The ability of bacteria to degrade oxalate and grow in oxalate-containing media, and the gene expression of Ox1T, an enzyme that catalyzes the transmembrane exchange of oxalate, also were investigated. RESULTS: The treatment resulted in a great reduction of the 24-hour excretion of oxalate in all six patients enrolled. Mean levels +/- SD were 33.5 +/- 15.9 mg/24 h at the end of the study period and 28.3 +/- 14.6 mg/24 h one month after treatment was interrupted compared with baseline values of 55.5 +/- 19.6 mg/24 h (P < 0.05). The treatment was associated with a strong reduction of the fecal excretion of oxalate in the two patients tested. Two bacterial strains among those used for the treatment (L. acidophilus and S. thermophilus) proved in vitro to degrade oxalate effectively, but their growth was somewhat inhibited by oxalate. One strain (B. infantis) showed a quite good degrading activity and grew rapidly in the oxalate-containing medium. L. plantarum and L. brevis showed a modest ability to degrade oxalate even though they grew significantly in oxalate-containing medium. No strain expressed the Ox1T gene. CONCLUSIONS: The urinary excretion of oxalate, a major risk factor for renal stone formation and growth in patients with idiopathic calcium-oxalate urolithiasis, can be greatly reduced with treatment using a high concentration of freeze-dried lactic acid bacteria. We postulate that the biological manipulation of the endogenous digestive microflora can be a novel approach for the prevention of urinary stone formation.

Technological and biological evaluation of tablets containing different strains of lactobacilli for vaginal administration.

Ten strains of lactobacilli were evaluated for the administration of viable microorganisms to restore the normal indigenous flora in the treatment of urogenital tract infections (UTI) in women. As the strains considered are facultative anaerobes, optimization of the production process was particularly critical to preserve bacterial viability. The microorganisms were formulated in single- and double-layer vaginal tablets. The two layers were characterized by different release properties: one is an effervescent composition that ensures a rapid and complete distribution of the active ingredient over the whole vaginal surface; while the second is a sustained release composition capable of releasing the lactobacilli over a longer period of time. Three different retarding polymers were tested, and all the formulations and tablets were evaluated in terms of technological processability, bacterial viability and stability, and cell adhesion properties of the microorganisms. From the results obtained, three out of ten strains appear particularly suitable for their application in the treatment of UTI. A larger batch of tablets made with a mixture of the three strains was then evaluated, confirming the feasibility of their industrial production and a good bacterial viability in the final dosage form.

Traditional and high potency probiotic preparations for oral bacteriotherapy.

Current research continues to improve the treatment options available to clinicians for oral bacteriotherapy. Recently, a greater understanding of the role of endogenous digestive microflora has generated renewed interest in the potential of oral bacteriotherapy for the management of a wide spectrum of gastrointestinal and systemic disorders. Several treatment strategies for oral bacteriotherapy have already entered clinical trials and it is hoped that some of these strategies will become widely available in the near future. This review summarises the current status of oral probiotic preparations for bacteriotherapy and discusses any obstacles to their successful clinical development. Newer probiotic preparations include high potency preparations that are greatly enriched in lactic acid bacteria, both in terms of bacterial concentrations and the number of bacterial strains. These preparations have a greater potential for clinical effectiveness than traditional preparations and are entering clinical evaluation especially in patients with inflammatory bowel disease and pouchitis, irritable bowel syndrome, or cryptosporidiosis. The pitfalls of previous clinical investigations of traditional probiotic preparations and the perils of future clinical trials with high potency preparations are discussed in the context of unmet needs and realistic expectations of success. Although considerable progress has been made in oral bacteriotherapy, focused efforts by basic scientists and clinical investigators and continued support from pharmaceutical companies is required to successfully develop probiotics for use in clinical medicine. Newer high potency probiotic preparations appear to have a great advantage over traditional preparations and should be the area of most active biomedical research in the field.

Outcome of cancer patients receiving home parenteral nutrition. Italian Society of Parenteral and Enteral Nutrition (S.I.N.P.E.).

BACKGROUND: Indication for home parenteral nutrition (HPN) in cancer patients is controversial because intestinal failure and malnutrition are often only two of the many problems found in such patients that may deserve priority of treatment. METHODS: This was a retrospective study of 75 cancer patients from nine institutions included in the Italian HPN Registry. The patients had a mean weight loss of 12.5%, serum albumin of 3.1 g/dL, lymphocyte count of 1150/mm3, and serum total iron-binding capacity of 190 micrograms/dL. The main indication for HPN was intestinal obstruction (66%); 72% of the patients had metastatic disease. A series of demographic, oncologic, and nutritional characteristics were analyzed in an attempt to predict a possible benefit of HPN. RESULTS: A total of 9897 days of HPN were delivered to 75 cancer patients, for a median of 4 months (range 1 to 15 months) per patient. Sixty-nine patients died while receiving HPN, five had a remission of their intestinal failure, and one chose to stop the treatment. Complications related to parenteral nutrition were as follows: 19 cases of sepsis, 6 catheter occlusions, 4 catheter dislocations, and 2 metabolic imbalances. HPN preserved nutritional status and slightly improved weight, lymphocyte count, serum albumin, and Karnofsky performance status in patients who survived > 3 months. Quality of life during HPN was judged by the clinicians to have improved in only 9% of those who survived < 3 months, but in 68% of the patients who survived for > 3 months. Karnofsky performance status > 50 at the start of HPN was correlated with longer survival (p = .02). CONCLUSIONS: Our study demonstrated a positive effect of HPN on nutritional status and quality of life in patients who survived > 3 months and suggests that HPN should be avoided when Karnofsky performance status is < 50.