Clinical Differences in Patients Infected with and Antimicrobial Susceptibility of Isolates Recovered at a Tertiary-Care Hospital in Korea.

Background: species are obligately anaerobic, gram-negative bacilli. Especially, and are highly relevant human pathogens. We investigated clinical differences in patients infected with spp. and determined the antimicrobial susceptibility of isolates.

Methods: We collected clinical data of 86 patients from whom spp. were isolated from clinical specimens at a tertiary-care hospital in Korea between 2003 and 2020. In total, 76 non-duplicated isolates were selected for antimicrobial susceptibility testing by the agar dilution method, according to the Clinical and Laboratory Standards Institute guidelines (M11-A9).

Results: was most frequently isolated from blood cultures and was associated with hematologic malignancy, whereas was mostly prevalent in head and neck infections. Anti-anaerobic agents were more commonly used to treat and infections than to treat infections. We observed no significant difference in mortality between patients infected with these species. All and isolates were susceptible to the antimicrobial agents tested. was resistant to clindamycin (48%) and moxifloxacin (24%), and F. mortiferum was resistant to penicillin G (22%) and ceftriaxone (67%). β-Lactamase activity was not detected.

Conclusions: Despite the clinical differences among patients with clinically important infections, there was no significant difference in the mortality rates. Some spp. were resistant to penicillin G, ceftriaxone, clindamycin, or moxifloxacin. This study may provide clinically relevant data for implementing empirical treatment against infections.