LIPOPOLYSACCHARIDE TOXINS

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LIPOPOLYSACCHARIDE TOXINS IN FOOD - A REVIEW
SCHOOL OF HEALTH TECHNOLOGY BIOMEDICAL
TECHNOLOGY D OLIVIER, P VENTER
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INTRODUCTION

• Foodborne diseases influence the health of
  individuals and the development of societies
• Microbial pathogens contaminate food and water
  supplies
• The WHO defines food hazards as biological,
  chemical, or physical agents in or property of
  food that may have an adverse health effect,

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FOOD SAFETY

• Food safety is non-negotiable
• Food safety all conditions and measures that
  are necessary during the production, processing,
  storage, distribution and preparation of food to
  ensure that it is safe, sound, wholesome and fit
  for human consumption
• The food industry is in constant battle with
  inevitable microbial contamination

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FOOD SAFETY (CONTINUE)

• Endotoxin (ET) release is poorly understood
• Highlight the importance of possible endotoxin
  release due to food preservation
• The pharmaceutical industry invests more
  resources into quality control and product safety

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LIPOPOLYSACCHARIDES (LPS)

• The LPS is an integral part of the outer membrane
  of Gram-negative bacteria
• Participate in the interaction of the bacterial
  cell with possible hosts and with the extrinsic
  environment.
• Are continuously liberated into the environment
  when the cells die, and during cell growth and
  division
• Many of the pathophysiological consequences of
  infection by Gram negative bacteria can be
  attributed to the activities of LPS as an ET

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STRUCTURE OF LPS

• Three separate regions
• Lipid A is the highly hydrophobic and
  endotoxically active part of the molecule.
• The core section of the molecule, which is
  covalently attached to lipid A
• Polymer of repeating subunits called the
  O-polysaccharide (O-chain)

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STRUCTURE OF SALMONELLA LPS
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LPS IN FOOD AND FOOD PROCESSING ENVIRONMENT

• Little is known about the role of LPS in the
  survival of Gram-negative bacteria in food and
  the food processing environment
• A parallel between the resistance of
  microorganisms and the efficacy of the sanitation
  processes in the food manufacturing industry is
  known to exist and is a direct result of the
  inherent ability of bacteria to adapt to a new
  environment and form increasingly resistant
  survival structures such as biofilms

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LPS IN FOOD AND FOOD PROCESSING ENVIRONMENT
(CONTINUE)

• Biofilm is recognised as a notable product safety
  hazard.
• Biofilm formation is a complex process, whose
  initial step is the adhesion of bacteria to a
  surface
• LPS play an important role in this process
• Biofilm are considered to be highly resistant to
  antimicrobial agents

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ET QUANTIFICATION

• Several methods have been developed during the
  last few decades for the quantification and
  qualification of endotoxins in both food and
  dairy products.
• These methods are categorised under pyrogen
  detection, immunological, chromatographic and
  electrophoretic methods.
• The Limulus method proved to be accurate and
  sensitive

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SANITIZERS AND LPS TOXICITY

• Several papers on the O-antigen ultra-structure
  and the influence of extrinsic and intrinsic
  factors thereon have been published in the last
  few decades
• Little mention has however been made of the
  influence of sanitizers applied in the food
  industry on the LPS structure

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SANITIZERS AND LPS TOXICITY (CONTINUE)

• LPS derived from E. coli O111 treated with a
  heavy-duty alkaline sanitizer had a change in
  toxicity per OD620nm higher than all the
  remaining treated LPSs including the control LPS
• The phenolic hand wash solution also resulted in
  a slight increase in toxicity,
• CIP chlorinated sanitizer reduced the toxicity
  compared to the control.

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SANITIZERS AND LPS TOXICITY (CONTINUE)

• The lipid A section of the LPS has been shown to
  constitute the endotoxic principle of LPS and
  therefore the mentioned change in the toxicity
  was expected to be reflected in the lipid A
  composition.
• This, however, did not seem to be the case for E.
  coli O111 as no correlation was noted with the
  toxicity.
• Weber-Frick and Schmidt-Lorenz (1988) who
  mentioned that any change in not only the lipid A
  but the entire O-polysaccharide structure would
  influence the results obtained by the LAL assay.

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CONCLUSION

• Kauffmann established a viable serotyping scheme,
  which is still accepted internationally today
• Rapid serotyping kits assess the O-antigen
  presence are readily available

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CONCLUSION (CONTINUE)

• LPS heterogeneity affect various cell surface
  properties
• Application of sanitizers in the food production
  environment should be carefully planned
• Doubtful whether the LAL assay will be an
  accurate method to verify the quantity of E. coli
  O111
• Effect of HPP and HHP

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• THANK YOU