Defining the Appropriate Length of Antimicrobial Therapy for Skull Base Osteomyelitis.

Objectives: Skull base osteomyelitis (SBO) is a rare infection comprising either the lateral (LSBO), central (CSBO), or both lateral and central (BSBO) skull base. Due to its rarity, the optimal length of antimicrobial therapy (AMT) has not been well defined. Therefore, the purpose of this study was to identify factors that may influence outcomes of SBO and formulate clearer recommendations on AMT duration.

Methods: A multi-institutional retrospective cohort study of SBO patients was conducted. Patient demographics, medical comorbidities, presenting symptoms, laboratory results, radiographic imaging, surgical treatment, culture results, length of follow-up, and type, length, and number of AMT courses were collected.

Results: Sixty-five patients were included. The average age was 66.5 years, and the average length of symptoms (LOS) prior to diagnosis was 3.74 months. The most common pathogen was Pseudomonas aeruginosa (n = 23) followed by coagulase-negative Staphylococcus species (n = 15). The average length of IV AMT was 6.8 weeks, and the average total length of AMT (TLA) was 15.7 weeks. Positive fungal cultures were associated with longer TLA (22.6 vs. 13.7 weeks, p = 0.02) and a greater number of distinct courses of AMT (4.1 vs. 2.7, p = 0.01).

Conclusion: In this series, the average length of IV AMT was 6.8 weeks. The average TLA was 15.7 weeks, indicating that a minimum of 6 weeks of IV AMT followed by a prolonged course of oral AMT is necessary to treat most cases of SBO. Fungal involvement significantly impacts the duration of AMT. Clinical guidelines are needed to better define the management of this complex disease.

Level of evidence: 4: