978. Effectiveness of oral cephalexin as completing treatment for bacteremic vertebral osteomyelitis caused by Methicillin-susceptible Staphylococcus aureus

Abstract

Abstract Background Methicillin-susceptible Staphylococcus aureus (MSSA) is the most common causative microorganism of pyogenic vertebral osteomyelitis (VO). Oral antimicrobial therapy with first-generation cephalosporins can treat MSSA infection, but data on pyogenic VO are scarce. Methods This retrospective study included adult patients treated with oral cephalexin as the completing treatment for pyogenic VO with bacteremia due to MSSA at the National Center for Global Health and Medicine Hospital, Japan from 2012 to 2020. Treatment effectiveness of cephalexin was evaluated by comparing the improvement in symptoms and laboratory and imaging results after intravenous (IV) administration of antimicrobial agents and after oral cephalexin treatment, using a 5-point scale (Table). A score of 4 or 5 indicated treatment success. Results This study included 15 patients (8 [53%] females), with median age 75 years (interquartile range [IQR], 67.5–80.5), median body weight 57.0 kg (IQR, 45.5–62.5), and median Charlson comorbidity index score 2 (IQR, 0–4). Ten patients (67%) had lesions in the lumbar spine. Six patients had lesions at multiple sites (cervical and thoracic, n=1; cervical and lumbar, n=2; thoracic and lumbar, n=1; and lumbar and sacral, n=2). Twelve patients (80%) had spinal abscesses and four (27%) had remote abscesses, but none had concomitant endocarditis. In 11 patients with normal renal function, 1,500–2,000 mg/day of cephalexin was administered. Surgical intervention was performed in five cases (33%). The median duration of IV antibiotics, cephalexin, and total treatment was 36 (IQR, 32–61; range, 21–86), 29 (IQR, 19–82; range, 8–251), and 86 (IQR, 59–125; range, 37–337) days, respectively. Majority patients (≥80%) received either cefazolin or ceftriaxone as IV therapy. Two patients used oral antimicrobials other than cephalexin outside of the cephalexin treatment period. Treatment success rate after cephalexin therapy was 87%. None of the patients had recurrence during a median follow-up of 119 days (IQR, 48.5-350). Conclusion In patients with bacteremic VO due to MSSA, completing treatment with cephalexin is a reasonable option, even in cases with spinal abscess, if at least 3 weeks of effective IV antimicrobial therapy is provided. Disclosures All Authors: No reported disclosures.