Describe of diphtheria.

 

                                  Describe lab diagnosis of diphtheria.

Causative organism of diphtheria is coryn bacterium It is gram positive, non-motile, rod shaped, non-acid fast bacilli, non-sporing and pleomorphic. Average size Is 3 µ /0.3 µ.

1. Examination of throat swab or laryngcal swab for albert staining.

Ø  Prepare smear from throat swab or laryngeal swab.

Ø  Dry air and fix over flame.

Ø  Pour albert-I for 5-7 mints.

Ø  Blot anmd dry with the help of filter paper.

Ø  Add Albert-II stain keep it for 3-5 mints.

Ø  Wash under tap water.

Ø  Diptheria bacilli shows met achromatic dot two pole of bacillius.

2. Culture from throat swab or laryngeal swab on. Loefflers serom agar and Tellurite blood agar.

Ø  Loefflers serum agar shows gram positive bacilli with metachromatic granule in 6-8 hours.

Ø  Tellurite blood agar shows three diphtheria bacillius (Gravis, Intermedius, mitis)

Ø  Gravis shows Daisy head colonies.

Ø  Intermedius shows frog egg colonies.

Ø  Mitis shows poached egg colony.

3. Virulence test by animal inoculation. Either subcutaneously or intradermal.

Ø  Both emulsion of the culture on loefflers shope is emulsified in 2-5 ml both and 0.8ml of emulsion injected sub-cutaneously in two guinea pig. 1^st Guniea pig gives 500units of antitoxin of C. diphtheria present, 2^nd Guniea pig will die in 54 days.

4. Eleks gel preparation test.

5. Culture on HELA Cell line:- Bacteria is identified by death of cells on cell line.

6. Schick test :- Skin test 0.2 ml of diphtheria toxin injected intradermaly on left for arm and similar does of toxin inactivated by heating at 70 ˚c of 30 mints injection.