Viability of Probiotics

Over the past five years we have endeavored to design a comestible product to be used as an alternative or adjunct to conventional renal therapy. Our investigations questioned the viability and efficacy of a lyophilized microbe after it has traveled through the intense pH extremes known to occur in the human alimentary tract and will enteric coating and/or microencapsulation overcome these potential pitfalls?. Eleven commercial probiotics were evaluated. Each was in a tablet form and contained one or more lyophilized bacterial strains. Bacterial counts in colony forming units (cfu) per tablet were given on the label for all but one of the products.

One tablet from each was aseptically crushed and bacterial enumeration of the “neat” tablet was determined. A second tablet was placed in artificial gastric juice for 1 hour. Bacterial enumeration was performed in a similar fashion. A third tablet was added to artificial intestinal fluid for 3 hours with subsequent bacterial enumeration. Six products yielded initial bacterial counts within 1 order of magnitude of that listed on the label. Three products demonstrated initial counts approximately 5 orders of magnitude less than listed. One product had no growth while the last did not list an initial bacterial count. After 1 hour in AGJ, 7 products did not demonstrate bacterial growth. Three products decreased in viability by more than 2 orders of magnitude while the final product demonstrated no change as compared to the “neat” tablet. After 3 hours in AIF, 5 products demonstrated growth within 1 order of magnitude of the neat, 5 products became more than 2 orders of magnitude less viable while the last not grow. Previous work demonstrated that microencapsulation in made no difference in urease activity compared to native bacteria and the above results demonstrate the effect of gastric juice on most probiotics. These data suggest that the combination of enteric coating and microencapsulation would best protect the microbe from the extremes of gastric passage and allow intact, viable bacteria to reach the large intestine where nitrogenous waste elimination will take place.