Page 78 - MNU-PM502- Pharmaeutical Microbiology Theoritical Book

Pharm D- Clinical Pharmacy Program Third Level Pharmaceutical Microbiology& Antimicrobials (PM 502)

Results: test is positive when

Each rabbit show increase in temperature more than 0.6 C

OR the sum of temperature increases of the 3 rabbits more than 1.4C

• If only 2 show an increase, repeat test using 5 rabbits and test will be positive
if 4 of 5 show increase in temperature.

2-LAL (Limulus Amebocyte Lysate) test

• based on clotting reaction of horseshoe crab blood to endotoxin

• faster, more economical and more sensitive than rabbit pyrogen test

Types of LAL test

A. Gel Clot Method

• Original method

The specimen is incubated with LAL of a known sensitivity.

Formation of a gel clot is positive for endotoxin

B. Turbidimetric Method

• A kinetic method

• The specimen is incubated with LAL and either the rate of increase
in turbidity

. Colorimetric Method

• Endotoxin catalyzes the activation of a proenzyme in LAL which
will cleave a colorless substrate to produce a colored endproduct,

measured spectrophotometrically and compared to a standard
curve.

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