1049. Outcome and Impact of Empirical Antimicrobial Treatment in Bacteraemia With Bacteroides Species; A Retrospective Cohort Study in a Region of Southern Sweden

BACKGROUND: Anaerobic infections are an important cause of bacteremia and severe Infections. Due to increasing extended spectrum β-lactamase resistance (ESBL), the treatment recommendations for anaerobic infections in Sweden have changed during the past ten years. The effects of anaerobe resistance and outcome for patients with anaerobe infections is unclear. METHODS: A retrospective cohort study was conducted in patients with bacteraemia due to Bacteroides species in the Region of Skåne between 2011 and 2015. Data on patients were reviewed from medical and microbiological records and we determined the factors associated with 28-day mortality using a multivariate regression model. RESULTS: Data on 454 patients were reviewed from medical and microbiological records and 389 (median age, 76 years; male, 54%) met the inclusion criteria. The 28-day all-cause mortality rate was 19% (72/389). Inadequate empirical antibiotic therapy occurred among 182 (47%) patients, and we found a trend toward that inadequate antibiotic treatment increased the 28-day mortality (P = 0.055). The frequency of bacteraemia with Bacteroides increased during the period of time and Bacteroides fragilis was the most common bacteria, 55% (212/389). The resistance against piperacillin/tazobactam was higher than in many other studies and among the different Bacteroides isolates that were resistant to piperacillin/tazobactam, Bacteroides thetaiotamicron was the most prevalent with 60% (50/83) being resistant. Piperacillin/tazobactam was the frequently used antimicrobial agent against Bacteroides infections and the utilization was increasing. We did not find any resistance among the Bacteroides isolates against metronidazole and only three isolates were resistant against carbapenems. CONCLUSION: Anaerobe resistance is an increasing issue and especially against the most common antibiotic treatment, piperacillin/tazobactam. Early recognition and appropriate treatment is important to avoid proliferation of these increasing bacteria since inadequate treatment increased the mortality. DISCLOSURES: All authors: No reported disclosures.