Published online by Cambridge University Press: 02 January 2015
In Bergey's manual, animal and human corynebacteria are a group of aerobic and facultatively anaerobic gram-positive or slightly curved bacilli that are generally nonmotile, catalase-positive, and non-acid fast. The best known and most clinically significant pathogen in the genus Corynebacterium is C. diphtheriae. However, other members of this genus are frequently encountered in the clinical laboratory and usually represent colonization or commensal contamination, since most other corynebacteria are of low virulence and questionable clinical significance. Frequently described as “diphtheroids,” such organisms are usually dismissed as contaminants and are not speciated or subjected to susceptibility testing. The JK diphtheroids may be differentiated from clinically unimportant “diphtheroids” by their resistance to beta-lactam antibiotics and their distinctive morphologic and cultural characteristics (Table 1).