This chapter presents Coryneform bacteria comprising aerobically or facultatively anaerobically growing, asporogenous, non‐acid fast Gram‐positive rods with irregular morphology. Establishing the clinical significance of coryneform bacteria can be difficult for caregivers and microbiologists.
Corynebacterium
spp. form the predominant group and include diphtheria toxin (DT)‐producing
Corynebacterium diphtheriae
, the causative agent of classic diphtheria, which was once a major cause of illness and death among children. Laboratory procedures for identification of
Corynebacterium
spp. and other coryneform bacteria include collection and transport of clinical samples, isolation practices, culture conditions, phenotypic and molecular assays, as well as antimicrobial susceptibility testing. Molecular techniques have been increasingly used in microbiology laboratories for the identification of
Corynebacterium
species and other coryneform bacteria. Detection of antibodies directed against DT is the only established serologic test for coryneform bacteria.