Application of the Limulus amoebocyte lysate test to the detection of gram-negative bacterial endotoxins in normal and mastitic milk

Abstract

The Limulus in vitro endotoxin assay was evaluated as a possible method for the prompt detection and measurement of endotoxins of Gram-negative bacteria in milk. Quantitative results were obtained following 1 h incubation of Limulus lysate and 10-fold dilutions of milk from normal quarters and from quarters of cows with clinical mastitis. This test was capable of detecting endotoxins associated with acute coliform mastitis. A positive Limulus reaction was recorded at dilutions ranging from 1: 10(4) to 1: 10(9) of milk from quarters affected with clinical mastitis due to coliform bacteria. Milk from normal quarters and from clinical mastitis cases due to Gram-positive bacteria was consistently negative to the test when diluted 1:10(3).