P-875. <i>Bacteroides</i> spp. drug resistance in patients with anaerobic bacteremia: a multicentric retrospective observational study

Abstract Background Bacteroides spp. are important causative anaerobes in intra-abdominal infections; however, recent reports have shown a trend toward drug resistance in non-Bacteroides fragilis. The present study aimed to evaluate bacteremia due to Bacteroides spp. by performing a multicentric retrospective observational study. Methods Obligate anaerobes isolated from blood culture specimens were collected from patients at Nagasaki University Hospital and five core hospitals in Toyama Prefecture from January 2012 to March 2022. Of a total of 528 patients, 102 specimens with B. fragilis and 72 with non-B. fragilis were clinically characterized using Fisher’s exact test and multiple logistic regression analysis. Drug-resistant rates over time were analyzed by the Spearman rank correlation test. Results In the non-B. fragilis group, compared to the B. fragilis group, the clindamycin resistance rate (non-B. fragilis group [59.7%] vs. B. fragilis group [38.2%] odds ratio [OR]=2.40 [95% confidence interval [CI]; 1.23–4.43] p=0.0058) and carbapenem resistance rate (non-B. fragilis group [27.8%] vs. B. fragilis group [10.8%] OR=3.18 [95%CI; 1.41–6.78] p=0.0049) was significantly increased. Furthermore, in the non-B. fragilis group, excluding patients who died owing to an underlying disease, a significantly increased 30-d mortality rate (non-B. fragilis group [16.7%] vs. B. fragilis group [5.9%] OR=3.20 [95%CI; 1.15–8.91] p=0.0251) was observed. Moreover, as of risk factors for 30-d mortality in non-B. fragilis bacteremia, SOFA score (adjusted OR=1.30 [95%CI; 1.11–1.57] p=0.0027) and carbapenem resistance (adjusted OR=7.05 [95%CI; 1.54–41.9] p=0.0171) were elucidated. Of note, in the non-B. fragilis group, rather than the B. fragilis group, the carbapenem resistance rate (non-B. fragilis group [r = 0.77, p=0.0141] vs. B. fragilis group [r = 0.17, p=0.6433]) and tazobactam/piperacillin resistance rate (non-B. fragilis group [r = 0.78, p=0.0120] vs. B. fragilis group [r = -0.05, p=0.8988]) have increased over time. Conclusion Non-B. fragilis isolated from blood cultures, compared to B. fragilis, exhibited an increasing trend in carbapenem and tazobactam/piperacillin resistance and contributed to 30-d mortality. Disclosures Shigeru Kohno, n/a, SHIONOGI &amp; CO., LTD.: Board Member|SHIONOGI &amp; CO., LTD.: Grant/Research Support Hiroshi Mukae, M.D., Ph.D., AstraZeneca: Lecture fees|Gilead Sciences: Lecture fees|GSK: Lecture fees|MSD: Advisor/Consultant|MSD: Lecture fees|Pfizer: Lecture fees|Shionogi &amp; Co., Ltd.: Advisor/Consultant|Shionogi &amp; Co., Ltd.: Grant/Research Support|Shionogi &amp; Co., Ltd.: Lecture fees