FAQ: Medical gloves and Endotoxin Testing

What are Endotoxins?

Dictionary definition: A heat-resistant pyrogen (specifically a lipopolysaccharide) found in the cell walls of certain pathogenic (disease-producing) bacteria.

Endotoxins are part of the outer cell wall of bacteria, invariably associated with Gram-negative bacteria as constituents of the outer membrane of the cell wall. Endotoxins are heat stable (boiling for 30 minutes does not destabilize endotoxin), but can be degraded by certain powerful oxidising agents (superoxide, peroxide and hypochlorite).

Why are endotoxins important?

Endotoxins are toxic to most mammals, and produce the same range of biological effects in the animal host.

Are there any recognised limits for endotoxins?

At present, there are no requirements in the UK or Europe for endotoxin levels on Natural Rubber Latex (NRL) medical gloves. However, the draft European standard (prEN 455 part 3) for medical gloves states that if the gloves are to be labelled "low endotoxin content", then the upper process limit shall be labelled on the packaging.

Why does SMTL recommend testing 3 batches ?

For new products and regular testing SMTL recommend preliminary testing followed by inhibition/enhancement studies on three separate lots before routine analysis. This is based on the USP and FDA recommendation of testing a minimum of 3 and a maximum of 10 batches for both inhibition/enhancement and routine testing. Extracts can be tested separately or pooled (which is cheaper).

References

A useful Internet document (on which much of the above is based) was available here -   http://www.bact.wisc.edu/Bact330/lectureendo - part of the University of Wisconsin-Madison Bacteriology Home Page.  However this link is unfortunately now dead.