Corynebacterium xerosis may be difficult to identify and it has been recognized that earlier isolates may have been previously misidentified as C. amycolatum. This organism has irregular staining with "barred" rods and club forms with occasional granules seen. Colonies tend to be yellowish, flat, dry, and granular with rough edges that grow well on sheep blood agar with no hemolysis.
While this organism does contain mycolic acids, it is partially acid-fast negative. Glucose, fructose, galactose, maltose, mannose, sucrose, and salicin are all fermented by C. xerosis but reactions may take 3-4 days to develop. It may be associated with endocarditis as well as post-surgical wounds, prostheses, and hospital-acquired pneumonia.
