Ingested probiotics reduce nasal colonization with pathogenic bacteria (Staphylococcus aureus, Streptococcus pneumoniae, and β-hemolytic streptococci)

As a bacterial reservoir, the nose may harbor potentially pathogenic bacteria (PPB: Staphylococcus aureus, Streptococcus pneumoniae, beta-hemolytic streptococci, and Haemophilus influenzae). In patients carrying PPB, antiseptic regimens could be crucial for infection control after major operations on or injuries of the head, nasal sinuses, or lungs. Such regimens may also be important for diabetic patients and persons receiving hemodialysis, in intensive care units, or with impaired immunity due to various other causes. We tested a possible effect of the ingestion of probiotics on the bacterial flora of the nose. In an open, prospective trial, 209 volunteers were randomly assigned to consume either a probiotic, fermented milk drink [65 mL with Lactobacillus GG (ATCC 53103), Bifidobacterium sp B420, Lactobacillus acidophilus 145, and Streptococcus thermophilus; n = 108] or standard yogurt (180 g; n = 101) daily for 3 wk. Nasal microbial flora were analyzed on days 1, 21, and 28. The microbial examination was blinded to the source of the samples. We found a significant reduction (19%; P < 0.001) in the occurrence of nasal PPB in the group who consumed the probiotic drink but not in the group who consumed yogurt. The effect was mainly on gram-positive bacteria, which decreased significantly (P < 0.05). The results indicate that regular intake of probiotics can reduce PPB in the upper respiratory tract. The results also indicate a linkage of the lymphoid tissue between the gut and the upper respiratory tract.