Corynebacterium diphtheriae: Difference between revisions
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==Overview== | ==Overview== | ||
''Corynebacterium diphtheriae'' is a pathogenic [[bacterium]] that causes [[diphtheria]]. It is a [[Facultative anaerobic organism|facultatively anaerobic]], [[Gram positive]] organism, characterized by non-encapsulated, non-sporulated, immobile, straight or curved rods. The [[genome]] of ''C. diphtheriae'' contains 2,488,635 [[nucleotides]], 2,389 [[genes]], and 69 structural [[RNA]] genes. [[Gram-stain]] will result in a blue-purple coloration due to containing [[polymetaphosphate]] [[granules]]. Many strains of ''C. diphtheriae'' produce [[diphtheria toxin]], a [[protein|protein]] [[exotoxin]], with a molecular weight of 62 [[Dalton (unit)|kilodaltons]] which ADP-ribosylates host [[Elongation factor|EF-2]], resulting in the inhibition of protein synthesis and producing signs of [[diphtheria]]. ''C. diptheriae'' is exclusively pathogenic in humans. ''C. diphtheriae'' can be classified into following four subspecies: ''mitis'', ''intermedius'', ''gravis'', and ''belfanti''. Diagnosis of''C. diphtheriae'' includes a [[Gram stain]] procedure; results will indicate [[gram-positive]], pleomorphic [[bacteria]] that will dye violet-blue and resemble clubs. ''C.diphtheriae'' causes [[diphtheria]] disease in non-immunized human hosts via secreted toxins. 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. [[Lysogenic]] conversion of nontoxigenic-toxigenic phenotypes of the [[bacterium]] can occur following transmission, allowing non-human/affected hosts to transmit [[diphtheria]] to humans. C. diphtheriae'' is sensitive to [[antibiotic]] therapy. | |||
==Morphology and | ==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 | *''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=Medical Microbiology |journal= |volume=4 |issue= |pages= |year=1996 |pmid=21413281 |doi= |url=}}</ref><ref name="pmid106070"></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> | |||
Many strains of ''C. diphtheriae'' produce [[diphtheria toxin]], a [[protein| | **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|protein]] [[exotoxin]], with a molecular weight of 62 [[Dalton (unit)|kilodaltons]] which ADP-ribosylates host [[Elongation factor|EF-2]], resulting in the inhibition of protein synthesis and producing signs of [[diphtheria]].<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> | |||
**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. | |||
*''C. diptheriae'' is exclusively 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. diphtheriae'' can be classified into the following four 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 intermedius'' | |||
*''C. diphtheriae gravis'' | |||
*''C. diphtheriea belfanti''<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> | |||
==Diagnosis== | ==Diagnosis== | ||
*Diagnosis of''C. diphtheriae'' includes a [[Gram stain]] procedure. | |||
**Results will indicate [[gram-positive]], pleomorphic [[bacteria]] that will dye violet-blue and resemble clubs.<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><ref name="pmid106070"> | |||
**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]] | |||
==External links== | ==External links== | ||
* [https://www.cebitec.uni-bielefeld.de/groups/gi/software/coryneregnet/ CoryneRegNet] - Database of Corynebacterial Transcription Factors and Regulatory Networks'' | * [https://www.cebitec.uni-bielefeld.de/groups/gi/software/coryneregnet/ CoryneRegNet] - Database of Corynebacterial Transcription Factors and Regulatory Networks'' | ||
==References== | |||
{{reflist|2}} | |||
[[Category:Infectious Disease]] | |||
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Corynebacterium diphtheriae | ||||||||||||
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Gram stained Corynebacterium diphtheriae culture
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Scientific classification | ||||||||||||
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Binomial name | ||||||||||||
Corynebacterium diphtheriae Kruse, 1886 |
Overview
Corynebacterium diphtheriae is a pathogenic bacterium that causes diphtheria. It is a facultatively anaerobic, Gram positive organism, characterized by non-encapsulated, non-sporulated, immobile, straight or curved rods. The genome of C. diphtheriae contains 2,488,635 nucleotides, 2,389 genes, and 69 structural RNA genes. 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, resulting in the inhibition of protein synthesis and producing signs of diphtheria. C. diptheriae is exclusively pathogenic in humans. C. diphtheriae can be classified into following four subspecies: mitis, intermedius, gravis, and belfanti. Diagnosis ofC. diphtheriae includes a Gram stain procedure; results will indicate gram-positive, pleomorphic bacteria that will dye violet-blue and resemble clubs. C.diphtheriae causes diphtheria disease in non-immunized human hosts via secreted toxins. 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. Lysogenic conversion of nontoxigenic-toxigenic phenotypes of the bacterium can occur following transmission, allowing non-human/affected hosts to transmit diphtheria to humans. C. diphtheriae is sensitive to antibiotic therapy.
Morphology and Structure
- C. diphtheriae is a facultatively anaerobic, Gram positive organism, characterized by non-encapsulated, non-sporulated, immobile, straight or curved rods.[1][2]
- The genome of C. diphtheriae contains 2,488,635 nucleotides, 2,389 genes, and 69 structural RNA genes.[3]
- 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, resulting in the inhibition of protein synthesis and producing signs of diphtheria.[4]
- 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 exclusively pathogenic in humans.[5]
Classification
C. diphtheriae can be classified into the following four subspecies:[1][2]
- 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 and resemble clubs.[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]
- 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:[8]
- Benzylpenicillin
- Ampicillin
- Oxytetracycline
- Erythromycin
- Cephaloradine
- Lincomycin
- Clindamycin
- Neomycin
External links
- CoryneRegNet - Database of Corynebacterial Transcription Factors and Regulatory Networks
References
- ↑ 1.0 1.1 1.2 Baron S, Murphy JR (1996). "Medical Microbiology". 4. PMID 21413281.
- ↑ 2.0 2.1 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.
- ↑ 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.
- ↑ 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.
- ↑ Zamiri I, McEntegart MG (1972). "The sensitivity of diphtheria bacilli to eight antibiotics". J. Clin. Pathol. 25 (8): 716–7. PMC 477485. PMID 4627747.