You can search "s boulardii contaminated with cerevisiae" and get plenty.
The following is from
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2868213/ Yeast probiotics, such as S. boulardii, are different from bacterial probiotics (different physiologic structures, large in size, do not acquire antibiotic-resistant genes and are not affected by antibiotics)[12]. Not only is there a confusing array of probiotic products on the global market, but the taxonomy of Saccharomyces strains has been debated[22].
One strain has received considerable discussion about
its valid nomenclature[23,24]. It was originally named S. boulardii in the 1950’s.
Advances in typing methods
opened a debate as to whether this strain should be reclassified as a strain of S. cerevisiae or remain a separate species.
Early work using PCR electrophoretic karotyping or rRNA sequencing methods reported that S. boulardii was indistinguishable from other strains of S. cerevisiae[24,25]. Newer metabolomic tools (microsatellite polymorphism analysis and retrotransposon hybridization analyses) show that S. boulardii has a unique clustering different from other strains of S. cerevisiae[26-28]. In addition, S. boulardii differs from other strains of S. cerevisiae by several metabolic and genetic characteristics[29,30].
S. boulardii persists longer in gnotobiotic mice models (10 d) compared with rapid clearance of other strains of S. cerevisiae (< 1 d)[31]. S. boulardii is also different physiologically and metabolically and its optimum growth temperature is 37°C and it is resistant to low pH and is tolerant to bile acids; whereas other strains of S. cerevisiae prefer cooler temperatures (30-33°C) and do not survive well in acid pH ranges[32-34].
S. boulardii can be distinguished from other strains of S. cerevisiae by advanced typing methods, by differences in metabolism and physiology and by the ability to have anti-pathogen effects (as discussed in the mechanisms of action section).
GUIDELINES FOR CHOOSING APPROPRIATE PROBIOTICS
Challenges in providing guidance to patients regarding the appropriate choice of probiotic include the wide diversity of available products on the market, variances in quality control, stability and formulations in those products, and the requirement to match the type of probiotic with the disease indication. The efficacy of probiotics have been shown to be both strain-specific and disease-specific[11,35,36].
Product to product variation
There are many different Saccharomyces products available commercially. Table Table11 lists some examples of products that contain S. boulardii, sold as probiotics either as lyophilized or heat-dried powders in capsules, or as one of several strains in a probiotic mixture in capsules or in liquid beverages[12,13,21,37-66].
The quality of these products from different sources have been found to vary. Choosing a probiotic product from a manufacturer with a regulated quality control program is a sound policy.
Unfortunately, many of the products available commercially may lack regulated quality control programs. Studies of other probiotics have found a wide diversity in both quality and contamination in products available on the Internet[67].
Marcobal et al[68] tested 14 commercial probiotics in the US and found 93% were incorrectly labeled (57% had contaminants and 36% did not list strains on the label). Masco et al[69] tested 58 different probiotic products from Europe, UK, Asia, Japan and Canada and found only 38% had the dose stated on the label and 29% did not contain strains listed on the label.
Not all products were found to have high standards of manufacture and quality control, as only some conform to Good Manufacturing Practices. Although most products state they contain at least 1 × 109 S. boulardii/mg, independent assays have determined 50% of the products contained a dose less than on the label.
In one study comparing six S. boulardii products, all had identical PCR typing profiles, but only 50% [Floratil (Merck), Flomicin (NeoChemical), and Florazin (Herald’s)], had the same concentration identified on their label. One product [Lactipan (Sigma Pharm)] had 2 × 104 fewer S. boulardii than stated on its label. One product [Floratil (Merck)], had the highest concentration (1 × 109/100 mL) and maintained high levels (9.5 × 108) six months later[70].
Even if the label states it contains S. boulardii, a variation in efficacy may occur due to lower than stated dose or inaccurate strain composition.
Four S. boulardii products were tested (along with one S. cerevisiae product) in Brazil. Only two (50%) of the S. boulardii products were protective in a Salmonella typhimurum mouse model (two S. boulardii products were ineffective, as well as the one S. cerevisiae product)[71].
Without access to specific quality control assays for commercially available probiotic products, the choice of a high quality product can be difficult.
One method of selecting a probiotic product is to find a product in which the manufacturing company has sponsored original clinical trials, as this indicates a degree of commitment that may not be present in companies that do not sponsor original research.
As shown in Table Table1,1, only a few S. boulardii probiotic products are supported by original research. Although at present, most probiotic clinical trials are sponsored by private companies, as more national funding becomes available, this situation may change.