Corynebacterium resistens sp. nov., a new multidrug-resistant coryneform bacterium isolated from human infections

Five strains of an unknown, multidrug-resistant coryneform, gram-positive rod were isolated from blood, bronchial aspirate, and abscess specimens. Four of the five strains isolated were highly resistant to antimicrobial agents, including beta-lactams, aminoglycosides, macrolides, quinolones, and tetracyclines, except for glycopeptides. In immunocompromised patients, bacteremia associated with this organism was rapidly fatal. This coryneform bacterium was nonmotile, lipophilic, and nonsaccharolytic. Lack of pyrazinamidase activity differentiated this organism from other lipophilic corynebacteria. Chemotaxonomic studies indicated that this multidrug-resistant coryneform bacterium belongs to the genus Corynebacterium. Comparative 16S rRNA gene sequencing and DNA-DNA hybridization analyses revealed that the five isolates were genetically identical and that they represent a new subline within the genus Corynebacterium, for which we propose the designation Corynebacterium resistens sp. nov. The type strain of Corynebacterium resistens is GTC 2026T (SICGH 158T, JCM 12819T, CCUG 50093T).