Detecting endotoxin activity in raw milk using an automated testing system

Abstract

Gram-negative bacteria are among the most common environmental pathogens causing mastitis. Endotoxin plays a major role in the pathophysiology of gram-negative bacterial sepsis; therefore, attempts have been made to detect and quantify it, with conflicting findings, in various states of infection. The simple and easy portable test system (PTS) for endotoxin activity offers several advantages over the traditional microplate kinetic limulus amebocyte lysate (LAL)-based test used by diagnostic laboratories. It is small, inexpensive and portable, requires only small quantities of raw milk, and provides results relatively rapidly in comparison to traditional methods. Thus the portability and ready availability of this cartridge system adds to its attractiveness for use in acute coliform mastitis (ACM). However, since the results obtained using this portable test will often dictate the course of clinical care and hygiene management, it is important that the cartridge system provides accurate information. The aim of the present study was to compare endotoxin activities detected in raw milk samples obtained from healthy dairy cattle without mastitis by a commercially available PTS™ and traditional microplate LAL-based assay, which determined activities using a kinetic turbidimetric (KT) assay.