Anaerobic bacteria can cause severe and life threatening infections. Susceptibility data are relatively limited on anaerobic organisms despite the clinical importance in guiding empiric treatment of infections. To determine antimicrobial susceptibility profiles of clinically significant anaerobic bacteria, isolates obtained from sterile sites submitted to Public Health Ontario Laboratory (2012–2019) were included in this study (N = 5712). Cefoxitin, clindamycin, metronidazole, meropenem, penicillin and piperacillin-tazobactam were tested using the gradient strip method with MICs interpreted based on Clinical and Laboratory Standards Institute guidelines. Bacteroides spp. (N = 958; 16.7%), Clostridium spp. (N = 798; 14.0%), Cutibacterium spp. (N =659; 11.5%) and Actinomyces spp. (N = 551; 7.0%) were the most commonly isolated genera. Bacteroides fragilis isolates were susceptible to cefoxitin (88.4%), clindamycin (68.4%), metronidazole (96.0%), meropenem (99.0%) and piperacillin-tazobactam (98.4%). Other Bacteroides spp. showed reduced susceptibility to several antimicrobials. Clostridium spp. isolates were susceptible to penicillin (69.7%), clindamycin (69.7%) and cefoxitin (76.3%); C. perfringens and C. ramosum showed distinct susceptibility profiles. Susceptibility rates among anaerobes remained relatively unchanged over 8 years with a few exceptions: C. perfringens susceptibility to clindamycin decreased from 91.3% to 60% (p = 0.03); Clostridium spp. susceptibility to penicillin similarly decreased from 82.1% to 65.9% (p = 0.03); Eggerthella spp. susceptibility to piperacillin-tazobactam decreased from 100% to 24.3% (p < 0.001); B. fragilis group susceptibility to cefoxitin decreased from 70.4% to 48.2% (p = 0.05); and Parabacteroides spp. susceptibility to piperacillin-tazobactam decreased from 100% to 25% (p = 0.01). Our findings underscore the need for ongoing surveillance and periodic monitoring of antimicrobial resistance in order to guide empiric therapy.

厌氧菌可引起严重的危及生命的感染。尽管在指导感染的经验性治疗方面具有临床重要性，但厌氧生物的敏感性数据相对有限。为了确定具有临床意义的厌氧菌的抗菌药物敏感性，从提交给安大略公共卫生实验室（2012-2019 年）的无菌场所获得的分离物被纳入本研究（N = 5712）。使用梯度条带法测试头孢西丁、克林霉素、甲硝唑、美罗培南、青霉素和哌拉西林-他唑巴坦，并根据临床和实验室标准协会的指南解释 MIC。拟杆菌属 (N = 958; 16.7%)，梭菌属。(N = 798; 14.0%),角质杆菌属 (N = 659; 11.5%) 和放线菌属。(N = 551; 7.0%) 是最常见的分离属。脆弱拟杆菌分离株对头孢西丁 (88.4%)、克林霉素 (68.4%)、甲硝唑 (96.0%)、美罗培南 (99.0%) 和哌拉西林-他唑巴坦 (98.4%) 敏感。其他拟杆菌属 对几种抗菌药物的敏感性降低。梭菌属 分离株对青霉素（69.7%）、克林霉素（69.7%）和头孢西丁（76.3%）敏感；C. perfringens和C. ramosum表现出不同的易感性特征。厌氧菌的易感率在 8 年内保持相对不变，但有一些例外：产气荚膜梭菌对克林霉素的敏感性从 91.3% 降至 60% (p = 0.03)；梭菌属 对青霉素的敏感性同样从 82.1% 降至 65.9% (p = 0.03)；Eggerthella属 对哌拉西林-他唑巴坦的敏感性从 100% 降至 24.3% (p < 0.001)；B. fragilis组对头孢西丁的敏感性从 70.4% 下降到 48.2% (p = 0.05)；和Parabacteroides spp。哌拉西林-他唑巴坦的敏感性从 100% 降至 25% (p = 0.01)。我们的研究结果强调需要持续监测和定期监测抗菌素耐药性，以指导经验性治疗。