Diphtheria: Difference between revisions

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[[Category:Pages edited by students of Tyrrell Conway at the University of Oklahoma]][[Image:OULOGOBIANCO.JPEG|thumb|230px|left|University of Oklahoma Study Abroad Microbiology in Arezzo, Italy[http://cas.ou.edu/study-abroad/]]]
[[Category:Pages edited by students of Tyrrell Conway at the University of Oklahoma]][[Image:OULOGOBIANCO.JPEG|thumb|230px|left|University of Oklahoma Study Abroad Microbiology in Arezzo, Italy[http://cas.ou.edu/study-abroad/]]]
[[Image:cdiphtheriametachromatic.jpg|thumb|400px|right|''C. diphtheriae'' bacteria, in green, showing metachromatic granules on the ends of the cell. From: http://textbookofbacteriology.net/diphtheria.html]]


==Etiology/Bacteriology==
==Etiology/Bacteriology==
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| Domain = [[Bacteria]]
| Domain = [[Bacteria]]
| Phylum = [[Actinobacteria]]
| Phylum = [[Actinobacteria]]
| Class = [[Actinobacteria]]
| Order = [[Actinomycetales]]
| Order = [[Actinomycetales]]
| Family = [[Corynebacteriaceae]]
| Family = [[Corynebacteriaceae]]
| Genus = [[Corynebacterium]]
| Genus = [[Corynebacterium]]
| Species = [[Diphtheriae]]
| Species = [[C. diphtheria]]
===Description===
===Description===
''C. diphtheriae'' infections are the causal agent of diphtheria. Four subspecies are recognized: ''C. d. mitis'', ''C. d. intermedius'', ''C. d. gravis'', and ''C. d. belfanti''. ''C. diphtheria'' is known to produce diphtheria toxins. ''C. diphtheria'' are Gram-positive, rod-shaped (and highly pleomorphic), aerobic, and nonmotile.
“Corynebacterium diphtheriae” is a gram-positive, non-motile, aerobic, and rod-shaped bacterium that causes diphtheria. There are four main subspecies that have been recognized: “C. diphtheriae mitis”, “C. diphtheriae intermedius”, “C. diphtheriae gravis”, and “C. diphtheriae belfanti”. “C. diphtheriae gravis” has the fastest generation time out of the four, allowing it to impose its toxic effects sooner. They can all be characterized as toxigenic or non-toxigenic, or those causing diphtheria and those that don’t, respectively. Diphtheria is an upper respiratory tract infection initially resulting in a sore throat and mild fever, but can progress to other more serious symptoms if not treated [[#References|[1]]]. It can also infect the skin when lesions are exposed to the bacteria. Even though there are thousands of reported cases each year, the threat of contracting or succumbing to this illness has dramatically decreased due to advancements in antibiotic treatment and development of vaccinations [[#References|[2]]].  
 
==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.
 
===Mechanism===
 
====Adherence====
 
====Invasion of the cell====
 
====Encountering macrophages====
 
==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.
 
==Diagnosis==
 
==Treatment==
 
==Prevention==
 
==Host immune response==
 
==References==
==References==
1 [http://textbookofbacteriology.net/diphtheria.html Online Textbook of Bacteriology. Diphtheria]
2 [http://link.springer.com.ezproxy.lib.ou.edu/book/10.1007/978-94-007-7624-1/page/1 Burkovski, Andreas (2014). "Corynebacterium diphtheriae" and related toxigenic species: Genomic, Pathogenicity, and Applications. New York: Springer]

Revision as of 20:56, 27 July 2015

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

Etiology/Bacteriology

Taxonomy

| Domain = Bacteria | Phylum = Actinobacteria | Order = Actinomycetales | Family = Corynebacteriaceae | Genus = Corynebacterium | Species = C. diphtheria

Description

“Corynebacterium diphtheriae” is a gram-positive, non-motile, aerobic, and rod-shaped bacterium that causes diphtheria. There are four main subspecies that have been recognized: “C. diphtheriae mitis”, “C. diphtheriae intermedius”, “C. diphtheriae gravis”, and “C. diphtheriae belfanti”. “C. diphtheriae gravis” has the fastest generation time out of the four, allowing it to impose its toxic effects sooner. They can all be characterized as toxigenic or non-toxigenic, or those causing diphtheria and those that don’t, respectively. Diphtheria is an upper respiratory tract infection initially resulting in a sore throat and mild fever, but can progress to other more serious symptoms if not treated [1]. It can also infect the skin when lesions are exposed to the bacteria. Even though there are thousands of reported cases each year, the threat of contracting or succumbing to this illness has dramatically decreased due to advancements in antibiotic treatment and development of vaccinations [2].

References

1 Online Textbook of Bacteriology. Diphtheria 2 Burkovski, Andreas (2014). "Corynebacterium diphtheriae" and related toxigenic species: Genomic, Pathogenicity, and Applications. New York: Springer