Monday, 3 February 2020

Using endotoxin testing to assess bacterial biofilms


Microbial biofilms - structured consortium of bacteria that are embedded in layers of self-produced polymer matrices, largely composed of polysaccharide, protein and DNA – are well described and known problems for pharmaceutical water systems and medical devices. What is less well-researched is the association of biofilms with endotoxin, especially within the pharmaceutical and medical device context. Here the association of biofilms and endotoxin is of significance to the risks presented by biofilms to water systems and for patient risks in relation to medical devices. With water systems the detection of endotoxin may provide an early warning of a biofilm problem. While the screening of Water-for-Injection systems for endotoxin is a GMP requirement, other types of pharmaceutical grade water are not commonly sampled for endotoxin testing. The introduction of this type of testing may prove useful where there is a concern about biofilm formation. The same may also apply to medical devices, especially given the risk posed from endotoxin. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could lead to infection.

In relation to this, Tim Sandle has written a review paper. Here is an extract:

The impact of endotoxin will be variable given that lipopolysaccharide size and composition are highly dynamic and vary according to the strain and growth conditions which contribute to the way by which bacteria adapt to changing environments. Nevertheless, endotoxin can potentially provide earlier warnings about biofilm developments than are possible with techniques like bioburden testing and assessments can also assist with the design of materials, especially those that do not readily bind endotoxin, and with in-use assessments.


This article discusses the association of biofilms and endotoxin; looks at the challenges this association poses for water systems and medical devices; and considers whether tests for endotoxin can function as part of a detection method to support an endotoxin control strategy.

The reference is:

Sandle, T. (2019) Endotoxin testing as a detection method for bacterial biofilms, American Pharmaceutical Review: Endotoxin Supplement 2019, 22 (6): 19-21

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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