Nasal carriage of Staphylococcus aureus in children with grass pollen-induced allergic rhinitis and the effect of polyvalent mechanical bacterial lysate immunostimulation on carriage status: A randomized controlled trial

Background: Numerous studies indicate that Staphylococcus aureus (S. aureus) colonizing the nasal cavity plays a role in the pathogenesis of allergic rhinitis (AR). This bacterium is able to produce a variety of toxins with superantigenic properties that can exacerbate allergic inflammation. Objective: The objective of the study was to evaluate the ability of polyvalent mechanical bacterial lysate (PMBL) to eliminate S. aureus nasal carriage in children with grass pollen-induced AR. Methods: This randomized, double-blind, placebo-controlled study included 80 children aged 5-17 years with seasonal AR (SAR). At the randomization visit and after 12 weeks of the study, a swab was taken from the region of the middle nasal meatus. Standard microbiology culture and identification techniques were used to analyze the swab contents. Results: Nasal colonization by S. aureus was confirmed in 29 children (42%), with Moraxella catarrhalis in three participants (4.4%). Physiological flora was detected in 37 children. No statistically significant differences were observed between the two measurement points in both the PMBL and placebo groups with respect to the number of patients whose nasal swab cultures showed a growth of S. aureus (p = 1). Both groups also showed no significant changes in the mean number of S. aureus colonies in nasal swab cultures taken at baseline and after 12 weeks of the study (PMBL group p = .41; placebo group p = .16). Conclusion: Almost every second child with SAR is S. aureus nasal carrier. Sublingual administration of PMBL in children with grass pollen-induced AR did not affect S. aureus nasal colonization. Therefore, PMBL should not be used for the eradication of S. aureus from the nasal cavity.