When Good Bugs Go Bad: Epidemiology and Antimicrobial Resistance Profiles of Corynebacterium striatum, an Emerging Multidrug-Resistant, Opportunistic Pathogen

Abstract

Infections with <i>Corynebacterium striatum</i> have been described in the literature over the last 2 decades, with the majority being bacteremia, central line infections, and occasionally, endocarditis. In recent years, the frequency of <i>C. striatum</i> infections appears to be increasing; a factor likely contributing to this is the increased ease and accuracy of the identification of <i>Corynebacterium</i> spp., including <i>C. striatum</i>, from clinical cultures. The objective of this study was to retrospectively characterize <i>C. striatum</i> isolates recovered from specimens submitted as part of routine patient care at a 1,250-bed, tertiary-care academic medical center. Multiple strain types were recovered, as demonstrated by repetitive-sequence-based PCR. Most of the strains of <i>C. striatum</i> characterized were resistant to antimicrobials commonly used to treat Gram-positive organisms, such as penicillin, ceftriaxone, meropenem, clindamycin, and tetracycline. The MIC₅₀ for ceftaroline was >32 μg/ml. Although there are no interpretive criteria for susceptibility with telavancin, it appeared to have potent <i>in vitro</i> efficacy against this species, with MIC₅₀ and MIC₉₀ values of 0.064 and 0.125 μg/ml, respectively. Finally, as previously reported in case studies, we demonstrated rapid <i>in vitro</i> development of daptomycin resistance in 100% of the isolates tested (<i>n</i> = 50), indicating that caution should be exhibited when using daptomycin for the treatment of <i>C. striatum</i> infections. <i>C. striatum</i> is an emerging, multidrug-resistant pathogen that can be associated with a variety of infection types.