corynebacterium diphtheriae b.carl
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Corynebacterium Corynebacterium diphtheriaediphtheriae
General CharacteristicsGeneral Characteristics
Gram PositiveGram Positive Club shaped rodClub shaped rod Forms clusters of “Chinese-Forms clusters of “Chinese-
characters”characters” Aerobic Aerobic Non-spore formingNon-spore forming Exterior fimbriae Exterior fimbriae Contains no plasmids Contains no plasmids Toxigenic and Non-toxigenic formsToxigenic and Non-toxigenic forms
Compound Light Compound Light MicroscopeMicroscope
The club or bar appearance of the cells is The club or bar appearance of the cells is due to pockets of inorganic phosphate due to pockets of inorganic phosphate which form metachromatic granules when which form metachromatic granules when stained stained
Electron MicroscopeElectron Microscope
ReservoirReservoir
Human BodyHuman Body Normal flora of skin and Normal flora of skin and
nasopharynx nasopharynx Enters upper respiratory tract and Enters upper respiratory tract and
cutaneouscutaneous
TransmissionTransmission
Spread by inhalation of airborne Spread by inhalation of airborne bacteria bacteria
Direct contacted with an infected Direct contacted with an infected person person
Open woundsOpen wounds
Virulence FactorsVirulence Factors Diphtheria toxin Diphtheria toxin
Diphtheria toxin gene is encoded by a Diphtheria toxin gene is encoded by a bacteriophagebacteriophage
Phage Beta Phage Beta DT inhibits of protein synthesis (elongation DT inhibits of protein synthesis (elongation
factor 2)factor 2) C. Diphtheria without this gene is not as C. Diphtheria without this gene is not as
harmfulharmful Repressor (DtxR) gene, is activated by iron Repressor (DtxR) gene, is activated by iron
and prevents transcription of the tox geneand prevents transcription of the tox gene High iron levels = no toxin releaseHigh iron levels = no toxin release Low iron levels = toxins releasedLow iron levels = toxins released
Clinical DiseasesClinical Diseases
Respiratory diphtheria is caused by Respiratory diphtheria is caused by C. C. diphtheriaediphtheriae bacteria adhering to and bacteria adhering to and colonizing the tonsils, nasal cavity, and colonizing the tonsils, nasal cavity, and throat throat
Cutaneous diphtheria can be caused by Cutaneous diphtheria can be caused by both the toxigenic and the nontoxigenic both the toxigenic and the nontoxigenic strains of strains of C. diphtheriaeC. diphtheriae Creates deep, erosive ulcers Creates deep, erosive ulcers
If left untreated could damage the heart If left untreated could damage the heart and nerves and eventually lead to death.and nerves and eventually lead to death.
Identification/DiagnosisIdentification/Diagnosis
Upper-respiratory tract illness characterized Upper-respiratory tract illness characterized by sore throat, low-grade fever, and an by sore throat, low-grade fever, and an adherent membrane of the tonsils, pharynx, adherent membrane of the tonsils, pharynx, and/or nose and/or nose Creates a pseudomembrane, a greenish-gray film that hardens Creates a pseudomembrane, a greenish-gray film that hardens
in the pharynx from inflammation and can cause asphyxiation. in the pharynx from inflammation and can cause asphyxiation.
Sample of the bacteria is isolated from the Sample of the bacteria is isolated from the patient’s throat/mouth and cultured patient’s throat/mouth and cultured
““Bull Neck” appearanceBull Neck” appearance To test for toxigenicity, the Elek test is To test for toxigenicity, the Elek test is
performed performed
SymptomsSymptoms
Cystine-Tellurite blood agar, Cystine-Tellurite blood agar, incubated at 35 degrees C in A incubated at 35 degrees C in A CO(2)-enriched atmosphere. CO(2)-enriched atmosphere. Colonies of Colonies of Corynebacterium Corynebacterium diphtheriaediphtheriae on tellurite containing on tellurite containing agar are gray-black, while most of agar are gray-black, while most of the usual oral flora are inhibited.the usual oral flora are inhibited.
TreatmentTreatment
Diphtheria infection is treated with Diphtheria infection is treated with diphtheria antitoxindiphtheria antitoxin
Formalin eliminated the toxicity of Formalin eliminated the toxicity of DT without destroying its DT without destroying its immunogenicity. Formalin-treated immunogenicity. Formalin-treated DT, now called diphtheria toxoid DT, now called diphtheria toxoid
14-day course of antibiotics, 14-day course of antibiotics, preferably Erythromycin or preferably Erythromycin or Penicillin Penicillin
PreventionPrevention Tdap (Adults) or DTaP (Under 7 yrs old) Tdap (Adults) or DTaP (Under 7 yrs old)
VaccinesVaccines combined vaccine against diphtheria, tetanus combined vaccine against diphtheria, tetanus
(Lockjaw), and pertussis (whooping cough) (Lockjaw), and pertussis (whooping cough)
Children should get 5 doses of DTaP vaccine, one dose at each of the following ages: 2 months 4 months 6 months 15-18 months 4-6 years
Prevention (cont.)Prevention (cont.)
Tdap A single dose of Tdap is recommended
for people 11 through 64 years of age. TdTd
Td, protects only against tetanus and diphtheria
recommended every 10 years.
QuestionsQuestions What is a common symptom of a toxigenic C. diphtheriae What is a common symptom of a toxigenic C. diphtheriae
infection?infection? a) Chickens Necka) Chickens Neck b) Bulls Neckb) Bulls Neck c) Giraffe’s neckc) Giraffe’s neck d) None of the Aboved) None of the Above
C. diphtheriae infection is treated with:C. diphtheriae infection is treated with: a) antibioticsa) antibiotics b) antitoxinsb) antitoxins c) no treatment except replenish waterc) no treatment except replenish water d) both a and bd) both a and b
ReferencesReferences Mandlik, A., Swierczynski, A., Das, A. and Ton-That, H. (2007), Mandlik, A., Swierczynski, A., Das, A. and Ton-That, H. (2007),
Corynebacterium diphtheriaeCorynebacterium diphtheriae employs specific minor pilins to employs specific minor pilins to target human pharyngeal epithelial cells. Molecular target human pharyngeal epithelial cells. Molecular Microbiology, 64: 111–124. doi: 10.1111/j.1365-Microbiology, 64: 111–124. doi: 10.1111/j.1365-2958.2007.05630.x 2958.2007.05630.x
Holmes, R.K. (2000) Biology and molecular epidemiology of Holmes, R.K. (2000) Biology and molecular epidemiology of diphtheria toxin and the tox gene. J Infect Dis 181 (Suppl. 1): diphtheria toxin and the tox gene. J Infect Dis 181 (Suppl. 1): S156–S167.S156–S167.
Coordinating Center for Infections Diseases/Division of Bacterial and Coordinating Center for Infections Diseases/Division of Bacterial and Mycotic Diseases "Diphtheria" 6 October 2005Mycotic Diseases "Diphtheria" 6 October 2005
Todar, Kenneth, University of Wisconsin-Madison Department of Todar, Kenneth, University of Wisconsin-Madison Department of Bacteriology, "Diphtheria" 2002Bacteriology, "Diphtheria" 2002
National Center for Immunization and Respiratory Diseases: Division of Bacterial National Center for Immunization and Respiratory Diseases: Division of Bacterial
Diseases, “Diphtheria”Diseases, “Diphtheria” February 7, February 7, 2011 2011 http://www.cdc.gov/ncidod/dbmd/diseaseinfo/diptheria_t.htmhttp://www.cdc.gov/ncidod/dbmd/diseaseinfo/diptheria_t.htm