How do you perform a Nagler test?
Streak the test organism in a straight line from the toxin-free agar half of the plate to toxin containing side. Repeat the same procedure with control strains on the same plate. Incubate anaerobically at 35-37°C for 24-48 hrs. Examine the plate for an opalescent halo around the inoculum and inhibition by antitoxin.
What is the Nagler test?
The Nagler test is a biochemical test that is used to identify organisms which liberate phospholipases (lecithinases) e.g. Clostridium perfringens.
Which culture media is used for the Nagler test?
For the identification of Clostridium perfringens and differentiating it from other Clostridia species, Egg Yolk Agar is used. It is an enriched, non-selective, and differential medium, and is also used in the Nagler Test for the presumptive identification of Clostridium perfringens.
How does the lecithinase test work?
Microorganisms that possess the enzyme lecithinase break down lecithin to insoluble diglyceride and phosphorylcholine, which results in a white opaque zone of precipitation that spreads beyond the edge of the colony.
What is the principle underlying the Elek test?
Elek’s test or the Elek plate test is an in vitro test of virulence performed on specimens of Corynebacterium diphtheriae, the bacteria that causes diphtheria. It is used to test for toxigenicity of C. diphtheriae strains. The test uses immunodiffusion.
What is the reverse CAMP test?
Reverse CAMP test can be used for differentiation of Clostridium perfringens from other Clostridium species. Here, a CAMP test positive Group B Streptococcus is streaked in the center of sheep blood agar, and Clostridium perfringens is streaked perpendicular to it.
How do you make egg yolk agar?
Suspend 50.41 grams in 900 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 50-55°C and aseptically add 100 ml Egg Yolk Emulsion (or add 10 ml of sterile egg yolk emulsion per 90 ml of medium).
What is lecithinase activity?
Lecithinase is a type of phospholipase that acts upon lecithin. It can be produced by Clostridium perfringens, Staphylococcus aureus, Pseudomonas aeruginosa or Listeria monocytogenes. C. perfringens alpha toxin (lecithinase) causes myonecrosis and hemolysis.
What is the size of diphtheria?
Diphtheria toxin (DT) is together with CT the best studied enterotoxin with regard to its structure and function. DT is a 58-kDa protein produced as a single polypeptide by lysogenic Corynebacterium diphtheriae strains.