Microbiological assessment of the quality of some commercial products marketed as Lactobacillus crispatus-containing probiotic dietary supplements

In the last decade, many authors have reported low viability for probiotic products. Investigators commonly find they are not meeting claimed active counts and/or incorrect species and/or strains have been identified. We have therefore decided to verify viability, the real dose and species correspondence in nine probiotic products (seven nutritional supplements and two medical devices) collected from the Italian and French markets claiming to contain at least one strain of L. crispatus among the different species/strain included in the formulation. In fact, the medical relevance of L. crispatus strains has recently grown., as evaluating the possible dominance clusters typical of the vaginal microbiota, the Community State Type I, the one dominated by L. crispatus, appears to be "protective" in terms of infections, fertility and gestational duration of pregnancy. The results obtained demonstrate the generally poor quality of probiotics. Out of nine products, only two definitely contained viable Lactobacillus crispatus cells with a daily dose of at least 1 × 109 CFU/g and with an acceptable correspondence with what is declared on the label. Among these two, only one was found to be formulated with a strain (M247) that has been scientifically documented