The role of the nasal microbiome in chronic rhinosinusitis (CRS) is generating increasing interest. A review article in the journal Pathogens details recent findings on the correlation between microbial residents in the sinonasal environment and the pathogenesis and chronicity of CRS.

“The prevalence of recalcitrant patients—those for whom symptoms persist despite long-term medical and surgical intervention—highlights the limitations of contemporary treatments and the need for individualized therapy grounded on a clearer understanding of the disease’s yet unknown etiology,” the researchers wrote.

A healthy sinus is neither sterile nor stable, the researchers explained. Staphylococcus and Corynebacterium genera appear to be core microbiota, although Haemophilus influenza and other upper airway pathogens are also in low relative abundance in healthy sinuses.

Investigators continued that the microbiome composition differs in patients with CRS. In a 2024 study, patients with CRS had a composition of 39.7% Staphylococcus, 9.7% Lactobacillus, and just 5.9% Corynebacterium, the authors reported, compared with 56.9% Staphylococcus, 16.8% Corynebacterium, and 10.6% Achromobacter in healthy controls.

“The ‘dysbiosis hypothesis’ proposes that inflammatory diseases are associated with significant shifts in the resident microbiota from a ‘healthy’ to a ‘diseased’ state,” the researchers wrote. “Antibiotics and steroids are the mainstays of treatment for CRS.”

Potential for Recurrence & Impact on QOL

Patients who undergo functional endoscopic sinus surgery to remove nasal polyps may experience postoperative changes in the nasal landscape that could alter microbiota into a diseased state of chronic inflammation. More and more, experts suspect microbial dysbiosis may be caused by a disrupted balance of bacteria and not a single pathogen.

The article also addressed inverted papillomas, benign mucosal polypoid lesions prone to recurrence and the propensity for malignant transformation in patients with a history of nasal infection.

“Viral culprits may induce an unhindered local immune response that contributes to the recurrence and chronicity of inverted papillomas.”

With patients reporting higher levels of QOL impairment with CRS than with other conditions such as congestive heart failure or angina, a better understanding of the disease’s development is important.

“Discerning between ‘healthy’ and ‘diseased’ sinonasal microbiomes and ‘keystone’ species could shed light on CRS etiology and provide the opportunity for CRS treatment tailored to an individual’s microbiome,” investigators wrote.