Corynebacterium

Corynebacterium diphtheriae

1. ✓ ✓ ✓

2. Corynebacterium diphtheriae

3. Morphology Corynebacterium diphtheriae 1. C.diphtheriae is club shaped gram positive bacilli that typically shows two characteristic features : a. Chinese letter arrangement or cuneiform arrangement b. Metachromatic granules

4. Morphology Corynebacterium diphtheriae Chinese letter arrangement They appear as V or L-shaped in smear, which is due to the bacterial cells divide horizontally and daughter cells tend to lie at acute angle to each other. This type of cell division is called snapping type of division.

5. Morphology Corynebacterium diphtheriae Metachromatic granules Present poles of bacilli Also called as polar bacilli/volutin granules Storage granules Granules are stained strongly gram-positive compared to remaining part of bacilli.

6. Morphology Corynebacterium diphtheriae Gram-positive bacilli C lub shaped swellings at the poles N onmotile N on-spore-forming

7. Virulence factors: Corynebacterium diphtheriae Diphtheria Toxin (DT) is the primary virulence factor responsible for diphtheria Toxin has Two fragments: A B Active Binding Fragment A helps in entry Fragment B is the binding fragment which binds to host receptor Diphtheria Toxin :

8. Virulence factors: Corynebacterium diphtheriae Diphtheria Toxin : Factors regulating Toxin production: Phage coded : DT toxin has β - Corynephage , carrying tox gene Iron concentration DT repressor Biotypes : 3 biotypes

9. Clinical manifestation: Corynebacterium diphtheriae Respiratory Diphtheria Cutaneous Diphtheria Systemic Diphtheria

10. Clinical manifestation: Corynebacterium diphtheriae Respiratory Diphtheria Site: Tonsil, Pharynx, nose, larynx Faucial Diphtheria Extension of pseudomembranous Bull neck appearance Incubation period: 3-4 days

11. Clinical manifestation: Corynebacterium diphtheriae Cutaneous Diphtheria Site: Skin Not Toxin-mediated Punched out ulcerative lesions Necrosis

12. Clinical manifestation: Corynebacterium diphtheriae Systemic Diphtheria Neurologic manifestations: Toxin mediated Myocarditis

13. Pathogenesis: Corynebacterium diphtheriae Pathogenesis of diphtheria is toxin mediated- Diphtheria is toxemia. Bacilli are non-invasive, secrete the toxins which spreads by bloodstream to various organs. Toxin is responsible for all type of manifestations including local (Respiratory) and systematic complications.

14. Laboratory Diagnosis: Corynebacterium diphtheriae Specimen: Throat swab or the portion of membrane Direct smear: Albert stain Gram stain Club shaped gram-positive bacilli with Chinese letter arrangement Green bacilli with bluish black metachromatic granules

15. Laboratory Diagnosis: Corynebacterium diphtheriae Culture: Enriched Media : Blood agar, Chocolate agar and Loeffler’s serum slope. Selective medium: Potassium tellurite agar, Tindale medium Biochemical identification : Hiss serum sugar media: Ferments Glucose, maltose and starch Urease test Negative

16. Laboratory Diagnosis: Corynebacterium diphtheriae Diphtheria Toxin Demonstration : In vitro: Elek’s gel precipitation test Detection of tox gene by PCR Detection of toxin by ELISA In vivo test:: Subcutaneous Intracutaneous test

17. Treatment : Corynebacterium diphtheriae Antitoxin Antibiotics: Penicillin or Erythromycin

18. Prophylaxis: Corynebacterium diphtheriae Active immunization is done with diphtheria toxoid as it induces antitoxin production in body Types: Single vaccine: Diphtheriae toxoid Combined Vaccine

19. Prophylaxis: Corynebacterium diphtheriae DPT VACCINE : D iphtheria toxoid, P ertussis (whole cell), T etanus toxoid Introduction Infants are immunized simultaneously against three important childhood diseases. Pertussis component act as adjuvant and increases immunogenicity of DT and TT.

20. Prophylaxis: Corynebacterium diphtheriae DPT VACCINE : D iphtheria toxoid, P ertussis (whole cell), T etanus toxoid Types : D iphtheria are prepared by two methods Plain formol toxoid: (FLUID TOXOID): Prepared by incubating toxoid with formalin Absorbed (ALUM ABSORDED): Formol toxoid is absorbed to to alum acts as adjuvant and increases the immunogenicity of toxoid .

21. Prophylaxis: Corynebacterium diphtheriae DPT VACCINE : D iphtheria toxoid, P ertussis (whole cell), T etanus toxoid Administration of DPT: DPT is scheduled under national immunization schedule in India Total five dose are given; 3 dose at 6,10,14 weeks followed by two booster dose at 16-24 month and 5 years SITE: Intramuscularly Protective titer: ≥0.01 unit/ml

22. Prophylaxis: Corynebacterium diphtheriae DPT VACCINE : D iphtheria toxoid, P ertussis (whole cell), T etanus toxoid Adverse reactions: Mild: fever Severe: Neurological complications