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==Morphology and Structure== | ==Morphology and Structure== | ||
*''C. diphtheriae'' is a [[Facultative anaerobic organism|facultatively anaerobic]], [[Gram positive]] organism, characterized by non-encapsulated, non-sporulated, immobile, straight or curved rods.<ref name="pmid21413281">{{cite journal |vauthors=Baron S, Murphy JR |title= |journal= |volume= |issue= |pages= |year= |pmid=21413281 |doi= |url=}}</ref> | *''C. diphtheriae'' is a [[Facultative anaerobic organism|facultatively anaerobic]], [[Gram positive]] organism, characterized by non-encapsulated, non-sporulated, immobile, straight or curved rods.<ref name="pmid21413281">{{cite journal |vauthors=Baron S, Murphy JR |title= |journal= |volume= |issue= |pages= |year= |pmid=21413281 |doi= |url=}}</ref> | ||
*The [[genome]] of ''C. diphtheriae'' contains 2,488,635 [[nucleotides]], 2,389 [[genes]], and 69 structural [[RNA]] genes.<ref name="Cerdeno-Tarraga2003">{{cite journal|last1=Cerdeno-Tarraga|first1=A. M.|title=The complete genome sequence and analysis of Corynebacterium diphtheriae NCTC13129|journal=Nucleic Acids Research|volume=31|issue=22|year=2003|pages=6516–6523|issn=1362-4962|doi=10.1093/nar/gkg874}}</ref> | |||
**As a [[gram-positive]] bacteria, ''C. diphtheriae'' contains a [[cell membrane]] and a [[lipid]]-rich [[murein]] layer outside. | |||
*[[Cell wall]] sugars of ''C. diphtheriae'' include [[arabinose]], [[galactose]], and [[mannose]]. | *[[Cell wall]] sugars of ''C. diphtheriae'' include [[arabinose]], [[galactose]], and [[mannose]]. | ||
*[[Gram-stain]] will result in a blue-purple coloration due to containing [[polymetaphosphate]] [[granules]]. | *[[Gram-stain]] will result in a blue-purple coloration due to containing [[polymetaphosphate]] [[granules]]. | ||
| Line 31: | Line 33: | ||
***Not all strains are toxigenic; the ability to produce the [[exotoxin]] is conferred on the bacterium when it is infected by a [[bacteriophage]] through a mechanism termed [[lysogenic]] activation. | ***Not all strains are toxigenic; the ability to produce the [[exotoxin]] is conferred on the bacterium when it is infected by a [[bacteriophage]] through a mechanism termed [[lysogenic]] activation. | ||
***A non-toxigenic strain can become toxigenic by the infection of such a bacteriophage. | ***A non-toxigenic strain can become toxigenic by the infection of such a bacteriophage. | ||
*''C. diptheriae'' is only pathogenic in humans.<ref name="pmid1749380">{{cite journal |vauthors=von Behring E, Kitasato S |title=[The mechanism of diphtheria immunity and tetanus immunity in animals. 1890] |language=German |journal=Mol. Immunol. |volume=28 |issue=12 |pages=1317, 1319–20 |year=1991 |pmid=1749380 |doi= |url=}}</ref> | |||
==Classification== | ==Classification== | ||
''C. | ''C. diphtheriae'' can be classified into the following three subspecies:<ref name="pmid21413281">{{cite journal |vauthors=Baron S, Murphy JR |title=Medical Microbiology |journal= |volume=4 |issue= |pages= |year=1996 |pmid=21413281 |doi= |url=}}</ref><ref name="pmid106070">{{cite journal |vauthors=Chang DN, Laughren GS, Chalvardjian NE |title=Three variants of Corynebacterium diphtheriae subsp. mitis (Belfanti) isolated from a throat specimen |journal=J. Clin. Microbiol. |volume=8 |issue=6 |pages=767–8 |year=1978 |pmid=106070 |pmc=275340 |doi= |url=}}</ref> | ||
*''C. diphtheriae mitis'' | *''C. diphtheriae mitis'' | ||
*''C. diphtheriae intermedius'' | *''C. diphtheriae intermedius'' | ||
| Line 42: | Line 45: | ||
*Diagnosis of''C. diphtheriae'' includes a [[Gram stain]] procedure. | *Diagnosis of''C. diphtheriae'' includes a [[Gram stain]] procedure. | ||
**Results will indicate [[gram-positive]], pleomorphic [[bacteria]] that will dye violet-blue, club-shaped resembling Chinese characters.<ref name="urlPinkbook | Diphtheria | Epidemiology of Vaccine Preventable Diseases | CDC">{{cite web |url=http://www.cdc.gov/vaccines/pubs/pinkbook/dip.html |title=Pinkbook | Diphtheria | Epidemiology of Vaccine Preventable Diseases | CDC |format= |work= |accessdate=}}</ref> | **Results will indicate [[gram-positive]], pleomorphic [[bacteria]] that will dye violet-blue, club-shaped resembling Chinese characters.<ref name="urlPinkbook | Diphtheria | Epidemiology of Vaccine Preventable Diseases | CDC">{{cite web |url=http://www.cdc.gov/vaccines/pubs/pinkbook/dip.html |title=Pinkbook | Diphtheria | Epidemiology of Vaccine Preventable Diseases | CDC |format= |work= |accessdate=}}</ref> | ||
* | *Additional tests include Albert's stain and Loeffler's stain. | ||
*''C. diphtheriae'' should be cultured on an erichment medium, namely to allow it to overgrow any other organisms present in the specimen.<ref>{{cite book |last=Nester |first=Eugene W. |year=2004 |title=Microbiology: A Human Perspective |edition=Fourth |location=Boston |publisher=McGraw-Hill |isbn=0-07-247382-7 |display-authors=etal}}</ref> | |||
**A selective plate [[tellurite agar]] which allows all ''Corynebacteria'' (including ''C. diphtheriae'') to reduce tellurite to metallic tellurium and produce brown colonies | |||
***''C. diphtheriae'' is the only [[corynebacterium]] that will produce a black halo around the colonies. | |||
==Pathophysiology== | |||
*''C.diphtheriae'' causes [[diphtheria]] disease in non-immunized human hosts via secreted toxins.<ref name="pmid21413281">{{cite journal |vauthors=Baron S, Murphy JR |title=Medical Microbiology |journal= |volume=4 |issue= |pages= |year=1996 |pmid=21413281 |doi= |url=}}</ref> | |||
**Toxigenic strains of the [[bacterium]] will secrete toxins in [[nasopharyngeal]] or skin [[lesions]]; it is common for hosts to carry ''C. diphtheriae'' in the [[nasopharyngeal]] region without displaying symptoms. | |||
**A low concentration of iron is required in the medium for toxin production; at high iron concentrations, iron molecules bind to a [[repressor]] which shuts down toxin production<ref>{{cite book |last=Nester |first=Eugene W. |year=2004 |title=Microbiology: A Human Perspective |edition=Fourth |location=Boston |publisher=McGraw-Hill |isbn=0-07-247382-7 |display-authors=etal}}</ref> | |||
*''C.diphtheriae'' is transmitted through [[respiratory]] droplets, secretions, or direct contact. | |||
*[[Lysogenic]] conversion of nontoxigenic-toxigenic phenotypes of the [[bacterium]] can occur following transmission, allowing non-human/affected hosts to transmit [[diphtheria]] to humans. | |||
==Sensitivity== | ==Sensitivity== | ||
''C. diphtheriae'' is sensitive to the following antibiotics:<ref name="pmid4627747">{{cite journal |vauthors=Zamiri I, McEntegart MG |title=The sensitivity of diphtheria bacilli to eight antibiotics |journal=J. Clin. Pathol. |volume=25 |issue=8 |pages=716–7 |year=1972 |pmid=4627747 |pmc=477485 |doi= |url=}}</ref> | |||
**[[Benzylpenicillin]] | |||
**[[Ampicillin]] | |||
**[[Oxytetracycline]] | |||
**[[Erythromycin]] | |||
**[[Cephaloradine]] | |||
**[[Lincomycin]] | |||
**[[Clindamycin]] | |||
**[[Neomycin]] | |||
==Genetics== | ==Genetics== | ||
==References== | ==References== | ||
Revision as of 15:37, 13 October 2016
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This page is about microbiologic aspects of the organism(s). For clinical aspects of the disease, see Diphtheria.
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];
| Corynebacterium diphtheriae | ||||||||||||
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 Gram stained Corynebacterium diphtheriae culture
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| Corynebacterium diphtheriae Kruse, 1886 |
Overview
Corynebacterium diphtheriae is a pathogenic bacterium that causes diphtheria. It is also known as the Klebs-Löffler bacillus, because it was discovered in 1884 by Germany|German bacteriologists Edwin Klebs (1834 – 1912) and Friedrich Löffler (1852 – 1915).
Morphology and Structure
- C. diphtheriae is a facultatively anaerobic, Gram positive organism, characterized by non-encapsulated, non-sporulated, immobile, straight or curved rods.[1]
- The genome of C. diphtheriae contains 2,488,635 nucleotides, 2,389 genes, and 69 structural RNA genes.[2]
- As a gram-positive bacteria, C. diphtheriae contains a cell membrane and a lipid-rich murein layer outside.
- Cell wall sugars of C. diphtheriae include arabinose, galactose, and mannose.
- Gram-stain will result in a blue-purple coloration due to containing polymetaphosphate granules.
- Many strains of C. diphtheriae produce diphtheria toxin, a protein exotoxin, with a molecular weight of 62 kilodaltons which ADP-ribosylates host EF-2, which results in the inhibition of protein synthesis and is responsible for the signs of diphtheria.[3]
- The inactivation of this toxin with an antitoxic serum (antitoxin) is the basis of the antidiphtheric vaccination.
- Not all strains are toxigenic; the ability to produce the exotoxin is conferred on the bacterium when it is infected by a bacteriophage through a mechanism termed lysogenic activation.
- A non-toxigenic strain can become toxigenic by the infection of such a bacteriophage.
- The inactivation of this toxin with an antitoxic serum (antitoxin) is the basis of the antidiphtheric vaccination.
- C. diptheriae is only pathogenic in humans.[4]
Classification
C. diphtheriae can be classified into the following three subspecies:[1][5]
- C. diphtheriae mitis
- C. diphtheriae intermedius
- C. diphtheriae gravis
- C. diphtheriea belfanti[6]
Diagnosis
- Diagnosis ofC. diphtheriae includes a Gram stain procedure.
- Results will indicate gram-positive, pleomorphic bacteria that will dye violet-blue, club-shaped resembling Chinese characters.[6]
- Additional tests include Albert's stain and Loeffler's stain.
- C. diphtheriae should be cultured on an erichment medium, namely to allow it to overgrow any other organisms present in the specimen.[7]
- A selective plate tellurite agar which allows all Corynebacteria (including C. diphtheriae) to reduce tellurite to metallic tellurium and produce brown colonies
- C. diphtheriae is the only corynebacterium that will produce a black halo around the colonies.
- A selective plate tellurite agar which allows all Corynebacteria (including C. diphtheriae) to reduce tellurite to metallic tellurium and produce brown colonies
Pathophysiology
- C.diphtheriae causes diphtheria disease in non-immunized human hosts via secreted toxins.[1]
- Toxigenic strains of the bacterium will secrete toxins in nasopharyngeal or skin lesions; it is common for hosts to carry C. diphtheriae in the nasopharyngeal region without displaying symptoms.
- A low concentration of iron is required in the medium for toxin production; at high iron concentrations, iron molecules bind to a repressor which shuts down toxin production[8]
- C.diphtheriae is transmitted through respiratory droplets, secretions, or direct contact.
- Lysogenic conversion of nontoxigenic-toxigenic phenotypes of the bacterium can occur following transmission, allowing non-human/affected hosts to transmit diphtheria to humans.
Sensitivity
C. diphtheriae is sensitive to the following antibiotics:[9]
Genetics
References
- ↑ 1.0 1.1 1.2 Baron S, Murphy JR. PMID 21413281. Missing or empty
|title=(help) - ↑ Cerdeno-Tarraga, A. M. (2003). "The complete genome sequence and analysis of Corynebacterium diphtheriae NCTC13129". Nucleic Acids Research. 31 (22): 6516–6523. doi:10.1093/nar/gkg874. ISSN 1362-4962.
- ↑ Nester, Eugene W.; et al. (2004). Microbiology: A Human Perspective (Fourth ed.). Boston: McGraw-Hill. ISBN 0-07-247382-7.
- ↑ von Behring E, Kitasato S (1991). "[The mechanism of diphtheria immunity and tetanus immunity in animals. 1890]". Mol. Immunol. (in German). 28 (12): 1317, 1319–20. PMID 1749380.
- ↑ Chang DN, Laughren GS, Chalvardjian NE (1978). "Three variants of Corynebacterium diphtheriae subsp. mitis (Belfanti) isolated from a throat specimen". J. Clin. Microbiol. 8 (6): 767–8. PMC 275340. PMID 106070.
- ↑ 6.0 6.1 "Pinkbook | Diphtheria | Epidemiology of Vaccine Preventable Diseases | CDC".
- ↑ Nester, Eugene W.; et al. (2004). Microbiology: A Human Perspective (Fourth ed.). Boston: McGraw-Hill. ISBN 0-07-247382-7.
- ↑ Nester, Eugene W.; et al. (2004). Microbiology: A Human Perspective (Fourth ed.). Boston: McGraw-Hill. ISBN 0-07-247382-7.
- ↑ Zamiri I, McEntegart MG (1972). "The sensitivity of diphtheria bacilli to eight antibiotics". J. Clin. Pathol. 25 (8): 716–7. PMC 477485. PMID 4627747.
External links
- CoryneRegNet - Database of Corynebacterial Transcription Factors and Regulatory Networks