237. Quantification and Composition of Commercially Available Probiotics
Session: Poster Abstract Session: Diagnostic Microbiology
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Probiotics are living organisms that, when consumed, have beneficial health effects for the host.  They can have immunomodulatory effects, alter the composition of the host microbial community, and inhibit and prevent colonization by pathogenic bacteria.   The consumption of food product and dietary supplement probiotics has increased rapidly in the United States in the past decade; however, the FDA has yet to approve any probiotic for therapeutic benefit and oversight is limited for these over-the-counter products. The aim of the project is to determine the composition and viability of commercially available probiotics. 

Methods: We selected 20 different probiotic products, both mono-cultures and multi-cultures, with different target populations (infants, children, adults) and different formulations (capsules, tablets, drops, food products).  We quantified the viable species from the probiotic products using serial dilutions on enriched media grown at 37 degrees Celsius in parallel aerobic and anaerobic conditions.  Colonies were then identified using PCR of the bacterial 16S rRNA gene through universal bacterial primers and Sanger sequencing. We also extracted DNA from the probiotic products and are performing MiSeq Illumina sequencing to detect non-cultureable or very rare species or contaminants. 

Results: From the probiotics we cultured and identified 7 Lactobacillus species: acidophilus, fermentum, gasseri, johnsonii, plantarum, reuteri, and rhamnosus GG, and Bifidobacterium longum, Lactococcus lactis, Propionibacterium freudenreichii, and Pediococcus pentosaceus.  We found that the majority of the commercially available probiotics contained approximately the number of viable bacteria that they advertised.  However, we did find that in some probiotic products containing multiple species there were fewer viable Bifidobacterium than Lactobacillus.  

Conclusion: Despite the lack of FDA regulation, overall we found that most of the popular probiotics that we tested contained the live organisms they claimed to; however, Bifidobacterium species may be underrepresented.

Yana Emmy Hoy-Schulz, PhD1, Saira Zaidi, BS1,2 and Julie Parsonnet, MD1, (1)Stanford University School of Medicine, Stanford, CA, (2)University of California, Berkeley School of Public Health, Berkeley, CA


Y. E. Hoy-Schulz, None

S. Zaidi, None

J. Parsonnet, None

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