Microbiomics of irrigation with xylitol or Lactococcus lactis in chronic rhinosinusitis

OBJECTIVE: Topical sinonasal rinse therapies may alter the local microbiome and improve disease control in chronic rhinosinusitis (CRS). The objective of this study was to examine microbiome changes in post‐surgical CRS patients when rinsing with commercially available products containing xylitol or Lactococcus lactis. METHODS: A crossover‐type protocol with a washout period was designed. Swab samples from anterior ethmoid cavities of CRS patients were collected prospectively at baseline. Subjects were provided packets containing either L. lactis W136 or xylitol in non‐blinded fashion and instructed to add it to their rinse bottles daily for 28 days, after which another swab was taken. A saline wash‐out period was completed and a third swab taken. A final 28‐day regimen of the opposite product was followed by a final swab. DNA extraction and sequencing of the 16S rRNA gene allowed for global microbiome analysis. RESULTS: We enrolled 25 subjects with CRS and 10 controls resulting in 70 adequate samples. Increased detection of Lactococcus was observed after use of L. lactis. No significant trends in alpha or beta diversity as a result of treatment were observed. SNOT‐22 score did not change significantly following treatment with xylitol, L. lactis, or saline. CONCLUSION: We did not detect any major clinical or microbiome‐level effect due to treatment with two topical rinse products. Further research is needed to elucidate their clinical utility and possible probiotic effect. LEVEL OF EVIDENCE: 3.