Cryptococcus neoformans

University of Oklahoma Study Abroad Microbiology in Arezzo, Italy[1]

File:Cdiphtheriametachromatic.jpg

C. diphtheriae bacteria, in green, showing metachromatic granules on the ends of the cell. From: http://textbookofbacteriology.net/diphtheria.html

Classification

Higher order taxa

Eukaryota (Kingdom); Fungi (Domain); Basidiomycota (Phylum); Tremellomycetes (Class); Tremellales (Order); Tremellaceae (Family); Cryptococcus (Genus)

Species

C. neoformans v. neoformans, C. neoformans v. grubii. A third variety, C. neoformans v. gattii, is now considered a distinct species, Cryptococcus gattii.

Pathogenesis

Virulence factors

Diphtheria toxin

Diphtheria toxin is an exotoxin that prevents protein synthesis through inactivation of eEF2 (eukaryotic elongation factor 2). This is done by ADP-ribosylating the amino acid diphthamide, inhibiting RNA translation.

Clinical features

Symptoms typically begin 2 to 7 days after infection. Diphtheria is characterized by sore throat, slight fever, fatigue, and an adherent membrane (called a pseudomembrane) on the tonsils, pharynx, and/or nasal cavity. Diphtheria toxin produced by C. diphtheriae can cause myocarditis, polyneuritis, and other systemic toxic effects. A milder form of diphtheria can be restricted to the skin.