Background
Anaerobic bacterial resistance trends may vary across regions or institutions. Regional susceptibility patterns are pivotal in the empirical treatment of anaerobic infections. We determined the antimicrobial resistance patterns of clinically important anaerobic bacteria, including recently named or renamed anaerobes.
Methods
A total of 521 non-duplicated clinical isolates of anaerobic bacteria were collected from a tertiary-care hospital in Korea between 2014 and 2016. Anaerobes were isolated from blood, body fluids, and abscess specimens. Each isolate was identified by conventional methods and by Bruker biotyper mass spectrometry (Bruker Daltonics, Leipzig, Germany) or VITEK matrix-assisted laser desorption ionization time-of-flight mass spectrometry (bioMérieux, Marcy-l'Étoile, France). Antimicrobial susceptibility was tested using the agar dilution method according to the CLSI guidelines. The following antimicrobials were tested: piperacillin-tazobactam, cefoxitin, cefotetan, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, tetracycline, and metronidazole.
Results
Most
Bacteroides fragilis
isolates were susceptible to piperacillin-tazobactam, imipenem, and meropenem. The non-
fragilis Bacteroides
group (including
B. intestinalis
,
B. nordii
,
B. pyogenes
,
B. stercoris
,
B. salyersiae
, and
B. cellulosilyticus
) was resistant to meropenem (14%) and cefotetan (71%), and
Parabacteroides distasonis
was resistant to imipenem (11%) and cefotetan (95%). Overall, the
Prevotella
and
Fusobacterium
isolates were more susceptible to antimicrobial agents than the
B. fragilis
group isolates. Anaerobic gram-positive cocci exhibited various resistance rates to tetracycline (6–86%).
Clostridioides difficile
was highly resistant to penicillin, cefoxitin, imipenem, clindamycin, and moxifloxacin.
Conclusions
Piperacillin-tazobactam, cefoxitin, and carbapenems are highly active β-lactam agents against most anaerobes, including recently named or renamed species.