Speakers - 2026

Title: Microbial colonization of the sphenoid sinus with Enterobacterales and Staphylococcus aureus in patients undergoing endoscopic transsphenoidal surgery

Abstract

The endoscopic endonasal transsphenoidal approach (EETA) is recognized as an effective and safe method for the resection of pituitary and sellar/suprasellar tumors. Classified as a clean-contaminated procedure, EETA entails intraoperative exposure to the nasal cavity, thereby introducing a potential risk of contamination with Staphylococcus aureus. The procedure also involves the sphenoid sinus - an anatomical region whose microbiological profile is poorly characterized in the current literature.

Materials and Methods. This prospective study included patients who underwent EETA between December 2024 and February 2025. All patients underwent microbiological testing of nasopharyngeal swabs, sphenoid sinus mucosa biopsies, gastrointestinal tract specimens, and endotracheal aspirates obtained via the endotracheal tube.

Results. A cohort of forty-one patients (21 male, 20 female), with a mean age of 61 years [52.7 ± 15.1], was enrolled in this study. Microbiological evaluation demonstrated substantial variation in the colonization prevalence of S. aureus and Enterobacterales, which ranged from 15% to 90% depending on the anatomical site. Bacterial growth was detected in sphenoid sinus mucosa biopsies in the vast majority of cases (90.2%, 37/41). Isolate similarity between the sphenoid sinus and other anatomical sites was low - only 19.5% of patients (8/41) with all matching isolates identified as Gram-positive organisms. These results underscore the inherent difficulty in the preoperative stratification of patients who may harbor microorganisms with potential resistance to standard perioperative antibiotic prophylaxis.

Conclusion. Microbial colonization of the sphenoid sinus was highly prevalent, detected in 90% of the analyzed mucosal biopsies. Gram-positive organisms (coagulase-negative staphylococci and Staphylococcus aureus), all beta-lactam susceptible, were most frequent.  Gram-negative Enterobacterales (26.8% of patients), including K. aerogenes, E. coli, E. cloacae complex, K. oxytoca, K. pneumoniae, M. morganii, exhibited significant resistance to penicillins (50%) and third-generation cephalosporins (30%). These findings suggest that the current perioperative antibiotic prophylaxis regimen may be inadequate for a significant subset of patients. Consequently, a revision of antimicrobial prophylactic strategies is warranted, particularly for individuals undergoing EETA who present with identified risk factors for postoperative meningitis.