In Vitro Antibiotic Susceptibility Pattern of Non-diphtheriae Corynebacterium Isolates in Ontario, Canada, from 2011 to 2016

Non-diphtheriae Corynebacterium-associated disease has been increasingly observed and often presents a conundrum to the treating physician. Analysis of antibiotic susceptibility testing data for 1,970 clinical Corynebacterium isolates received between 2011 and 2016 revealed that empirical drug treatment options are limited to vancomycin and linezolid. Corynebacterium striatum was the most frequently observed species during this study period, along with C. amycolatum and C. pseudodiphtheriticum/C. propinquum. Low levels of susceptibility to penicillin (14.5%), erythromycin (15.1%), and clindamycin (8.7%) were observed for non-diphtheriae Corynebacterium species, while 3.0% of isolates were not susceptible to daptomycin. Similarly, 26.9% and 38.1% of Corynebacterium isolates were susceptible to ciprofloxacin and trimethoprim-sulfamethoxazole, respectively. Our data show much lower susceptibility to penicillin than previously reported in the literature and an increasing number of isolates resistant to daptomycin, highlighting the need for continued antibiotic surveillance studies for appropriate patient management and treatment success.