All of the following are true of diphtheria except a) a...

Name: Problem 2, Chapter 21: Nester's Microbiology: A Human Perspective
Uploaded: 2021-06-30T13:53:24-08:00
Duration: 1 min 48 s
Channel: Joanna Quigley
Description: All of the following are true of diphtheria except a) a membrane that forms in the throat can cause suffocation. b) a toxin is produced that interferes with ribosome function. c) the causative organism typically invades the bloodstream. d) immunization with a toxoid prevents the disease. e) nerve injury with paralysis is common.

All of the following are true of diphtheria except a) a membrane that forms in the throat can cause suffocation. b) a toxin is produced that interferes with ribosome function. c) the causative organism typically invades the bloodstream. d) immunization with a toxoid prevents the disease. e) nerve injury with paralysis is common.

All of the following are true of diphtheria except
a) a membrane that forms in the throat can cause suffocation.
b) a toxin is produced that interferes with ribosome function.
c) the causative organism typically invades the bloodstream.
d) immunization with a toxoid prevents the disease.
e) nerve injury with paralysis is common.

Key Concepts

Non-invasive Nature of the Organism

Unlike many invasive bacterial infections, the diphtheria bacillus (Corynebacterium diphtheriae) typically remains localized within the upper respiratory tract. It produces a toxin that disseminates and causes systemic effects, but the bacteria themselves are not known for extensive bloodstream invasion, which distinguishes its pathogenesis from other invasive infections.

Pseudomembrane Formation and Airway Obstruction

A characteristic feature of diphtheria is the development of a grayish pseudomembrane on the tonsils and throat. This pseudomembrane can adhere tightly to the underlying tissue and, if extensive, may obstruct the airway, posing a risk of suffocation or breathing difficulties, particularly in young children.

Immunization with Toxoid

Prevention of diphtheria is achieved through vaccination with a toxoid, a modified form of the diphtheria toxin that is rendered non-toxic but still elicits an immune response. This immunization strategy is highly effective in providing protection against the effects of the toxin, which is the major virulence factor of the disease.

Diphtheria Pathogenesis

Diphtheria is primarily a toxin-mediated disease where the bacteria colonize the upper respiratory tract and produce a potent toxin, rather than invading the bloodstream extensively. The pathology is largely due to the toxin’s systemic effects after being absorbed from the localized site of infection, rather than from widespread bacterial invasion.

Toxin Mechanism

The diphtheria toxin works by inactivating elongation factor-2 (EF-2) in host cells through ADP-ribosylation, which halts protein synthesis. This inhibition of ribosomal function leads to cell death and tissue damage, thereby accounting for many of the clinical manifestations of the disease.

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