Alteration in bacterial culture after treatment with topical mupirocin for recalcitrant chronic rhinosinusitis

IMPORTANCE Topical mupirocin therapy is used to treat symptomatic chronic sinusitis (CRS). However, the potential adverse impact of this therapy on the sinus microbiota has not been well quantified. OBJECTIVE To determine changes in microbiologic culture results before and after topical mupirocin therapy in patients with CRS with medically and surgically refractory disease. DESIGN, SETTING, AND PARTICIPANTS We performed a retrospective medical chart review for 22 consecutive adults evaluated and treated between January 1, 2012, and January 1, 2014, at an otolaryngology-rhinology clinic at a regional academic medical center. The patients were 14 men and 8 women, who had undergone functional endoscopic sinus surgery for CRS, and in whom sinus aspirate cultures were performed before and after topical mupirocin therapy for symptomatic disease. Analyses were performed in April 2014. EXPOSURES Patients underwent treatment with saline sinus rinse, with the addition of mupirocin, for at least 1 week. MAIN OUTCOMES AND MEASURES Bacterial isolates from sinus aspirate culture. RESULTS The patients included 14 men and 8 women, 18 to 75 years old, who underwent a mean of 1.9 functional endoscopic sinus surgical procedures. The mean (range) duration of mupirocin therapy was 6 (2-12) weeks. Before mupirocin therapy, cultures from symptomatic patients (14 men and 8 women, ages 18-75 years) revealed common bacteria implicated in CRS, which are characteristically gram-positive. After mupirocin therapy, cultures from symptomatic patients shifted significantly: 19 were gram-positive vs 3 gram-negative before treatment; 9 were gram-positive vs 13 gram-negative after treatment (P = .004), with increased growth of pathogenic gram-negative bacteria and Corynebacterium. CONCLUSIONS AND RELEVANCE These data present evidence supporting the distinct abrogation of culturable sinus bacteria after mupirocin rinses, identifying a shift toward increased pathogenic bacteria. Consideration of healthy host microbiome and immune dysfunction should guide future treatment considerations.