Pathogenic JK group corynebacteria and their similarity to human cutaneous lipophilic diphtheroids

Aerobic diphtheroids from human skin (commonly referred to as lipophilic diphtheroids), pathogenic bacteria of the JK group, and classic species of the genus Corynebacterium were studied for their cellular fatty acids and mycolates, composition of their cell wall peptidoglycans, nutritional requirements, biochemical reactions, and antibiotic sensitivities. Lipophilic diphtheroids and JK strains were catalase positive and contained corynemycolic acid and meso-diaminopimelic acid in their cell walls, a characteristic shared with all corynebacteria. The lipophilic diphtheroid and JK strains were found to have a strict nutritional requirement for lipid and a similar composition of cellular fatty acid, mycolic acid, and peptidoglycan; they differed only in the multiple antibiotic resistance of the JK strains. Results of the biochemical reactions were inconclusive and did not permit grouping of lipophilic diphtheroids or JK with any of the reference strains. The reference strains did not require lipid and contained cellular fatty acids that were clearly distinct from those of the JK strains or lipophilic diphtheroids. These results suggest that JK bacteria are Corynebacterium spp. and may represent resident lipophilic diphtheroids that have acquired antibiotic resistance.