Ingested probiotics reduce nasal colonization with pathogenic bacteria (Staphylococcus aureus, Streptococcus pneumoniae, and b-hemolytic streptococci)
Am J. Clin. Nutr. 77:517-520
Glück, U. and J.-O. Gebbers. 2003
Summary and comments by Mary Ellen Sanders, Ph.D.
One of the oft-touted but still speculative benefits of probiotics is the role they might play in decreasing the transmission of pathogens in institutions or areas of high population density. There are smatterings of studies supporting such a benefit. Saavedra, et al. (1994) demonstrated that infants hospitalized for infectious diarrhea who consumed a probiotic preparation were less likely to shed rotavirus than the control group. In studies on animals, several probiotic-based products have been tested for their ability to reduce the shedding of enteric pathogens in horses, cattle, swine and poultry (Nisbet, 2002). One product, Preempt®, is available commercially for use in decreasing Salmonella contamination of baby chickens.
This paper by Glück et al. (2003) provides some additional insight into the ability of some probiotics to reduce the likelihood that you are a source of pathogens. This study, conducted in Switzerland, recruited 209 healthy adults. Of these, 119 were found to harbor potentially pathogenic microbes (Staphylococcus aureus, Streptococcus pneumoniae, or b-hemolytic streptococci) in their nasal cavity. Sixty-eight (68) subjects consumed a probiotic beverage containing L. rhamnosus GG, L. acidophilus 145, S. thermophilus (strain not identified) and Bifidobacterium sp. B420 (total daily dose for each bacterium was 3×109-3×1010) for 3 weeks. The control group consumed standard yogurt containing only S. thermophilus and Lactobacillus bulgaricus at >1.8×109/day. The number of carriers of potentially pathogenic bacteria dropped 19% in the probiotic group whereas no change was observed in the control group. These results are even more compelling, considering the products were consumed orally and there was no direct contact between the probiotic product and the nasal cavity. This study suggests that oral intake of a probiotic milk beverage can reduce upper respiratory tract pathogens, which according to the authors, links ‘lymphoid tissue between the gut and the upper respiratory tract’.
Saavedra JM, Bauman NA, Oung I, Perman JA, Yolken RH.
Feeding of Bifidobacterium bifidum and Streptococcus thermophilus to infants in hospital for prevention of diarrhoea and shedding of rotavirus.
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Nisbet D. Defined competitive exclusion cultures in the prevention of enteropathogen colonisation in poultry and swine.
Antonie Van Leeuwenhoek. 2002 Aug;81(1-4):481-6.