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Harrison's Principles of Internal Medicine, 18e
| Part 8. Infectious Diseases > Section 5. Diseases Caused by Gram-Positive Bacteria > |
Chapter 138. Diphtheria and Other Infections Caused by Corynebacteria and Related Species
Sections: Diphtheria, Nondiphtherial Corynebacteria and Related Species, Further Readings.
Topics Discussed: corynebacterium infections.
Excerpt:"Diphtheria is a nasopharyngeal and skin infection caused by Corynebacterium diphtheriae. Toxigenic strains of C. diphtheriae produce a protein toxin that causes systemic toxicity, myocarditis, and polyneuropathy. The toxin is associated with the formation of pseudomembranes in the pharynx during respiratory diphtheria. While toxigenic strains most frequently cause pharyngeal diphtheria, nontoxigenic strains commonly cause cutaneous disease.C. diphtheriae is a gram-positive, unencapsulated, nonmotile, nonsporulating bacillus. C. diphtheriae organisms have a characteristic club-shaped bacillary appearance and typically form clusters of parallel rays (palisades) that are referred to as Chinese characters. In the specific laboratory media recommended for the cultivation of C. diphtheriae, tellurite, colistin, or nalidixic acid allows selective isolation of the organism in the presence of other autochthonous pharyngeal microbes. Human isolates of C. diphtheriae may display nontoxigenic (tox–) or toxigenic (tox+) phenotypes. Corynebacteriophage beta carries the structural gene (tox) encoding diphtheria toxin, and a family of closely related corynebacteriophages are responsible..."
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