Bacterial counts from five over-the-counter probiotics: are you getting what you paid for?

There is concern that the bacterial colony counts present at the time of manufacture and listed on the probiotic package may not be reflective of the numbers viable colonies at the time of purchase and patient consumption thereby diminishing efficacy. We performed a colony count study of three separate samples of five different probiotics purchased from three different stores: Bifidobacterium infantis (Align(®)); Lactobacillus acidophilus CL1285(®) and Lactobacillus casei LBC80R(®) (Bio-K+(®)); Lactobacillus rhamnosus GG (Culturelle(®)); Saccharomyces boulardii (Florastor(®)) and "L. acidophilus" and "Lactobacillus helveticus" (Lactinex(®)). Approximately 1 g of powder of each (Lactinex(®) tablets were crushed before testing) was reconstituted in sterile distilled water, serial 10-fold dilutions were prepared and plated in duplicate onto blood agar plates, with incubation for 48 h in an anaerobic chamber (except the Saccharomyces which was incubated aerobically) after which colony counts were performed. The Florastor(®) packaging did not state an expected concentration and was found to have 9.2 × 10(9)-1.3 × 10(10) CFU/g. Lactinex(®), Align(®), Bio-K+(®), and Culturelle(®) had viable colony counts that were similar to those stated on the package.