589. Clinical Outcomes of Twice versus Thrice daily Metronidazole Dosing for <i>Bacteroides</i> Bloodstream Infections

Abstract Background The optimal metronidazole dose for the treatment of Bacteroides spp. has not been defined. purpose this study was to evaluate utility a twice (BID), rather than thrice (TID) daily dosing strategy among patients with bacteremia due Methods Adult, hospitalized secondary between October 2010 and June 2021 were assessed across 11 hospitals. primary endpoint clinical failure which composite all-cause 30-day mortality, escalation antimicrobial therapy, readmission or recurrence an anaerobic infection, positive repeat blood cultures spp., resolve leukocytosis fever. Results 208 included; 68 received 500mg BID 140 TID (Figure). Patient age, Charlson comorbidity index, Pitt Bacteremia score similar receiving vs (Table 1). On balance, who more likely receive oral had shorter lengths hospitalization prior bacteremia. Overall, there no significant difference rates other outcomes versus 2). In multivariate model, neither use (OR = 0.74; 95% CI 0.33–1.65; P=0.457), time initiation 1; 0.81–1.22; P=0.968), days initial non-metronidazole therapy 0.91; 0.59–1.34; P=0.646), pre-infection length stay 1.02; 0.99–1.05; P=0.106), admission 2016 1.09; 0.49–2.39; P=0.829), 0.45; 0.18–1.03; P=0.066) significantly associated failure. Figure 1:Inclusion exclusion Non-metronidazole coverage consisted beta-lactam/beta-lactamase inhibitor, cefoxitin, carbapenem Table 1:Demographics baseline characteristicsTable 2:Clinical outcomes*Patients considered have escalated if, in setting ongoing signs infections, either broadened frequency increased from daily. Conclusion largest date treated metronidazole, strategies. absence clear benefit, is reasonable lieu infections Disclosures Ryan K. Shields, PharmD, MS, Infectious Disease Connect: Advisor/Consultant|Merck: Grant/Research Support|Roche: Support.