The effect of intraoperative mupirocin irrigation on Staphylococcus aureus within the maxillary sinus.

Antibiotic irrigations are occasionally used during endoscopic sinus surgery when gross mucosal infection is present. These irrigations are thought to flush out pathogenic bacteria and decrease the bacterial load within the mucosal surfaces. This treatment, however, has not been studied in vivo and it is unknown whether antibiotic rinses produce a quantitative reduction in pathologic bacteria within the sinus mucosa. The objective of this study was to determine the relative abundance of Staphylococcus aureus within the maxillary sinus and to evaluate the impact of intraoperative mupirocin irrigation on bacterial burden. Sixteen patients with symmetric maxillary chronic rhinosinusitis were prospectively enrolled. After bilateral maxillary antrostomies, biopsies were taken of the maxillary sinus mucosa on both sides. In each patient, the right side was irrigated with 240 mL of normal saline (NS) and the left side was irrigated with 240 mL of NS mixed with 60 mg mupirocin. Repeat maxillary sinus mucosal biopsies were taken from each side 7 to 10 days postsurgery. Each biopsy was analyzed using quantitative polymerase chain reaction to determine the presence and relative amount of S. aureus. Mupirocin irrigations were found to significantly reduce the amount of S. aureus found within the maxillary sinus mucosa compared to NS alone. The average fold change between the pre- and posttreatment biopsies on the right and left was 9.05 and 97.42, respectively (p < 0.01). Intraoperative mupirocin irrigations significantly reduce the amount of S. aureus detected within the diseased sinus mucosa at up to 10 days postoperatively.