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Interactions of ocular isolates of gram-negative bacteria with lactoferrin
Timothy J Williams1, Mark D P Willcox, Rene P Schneider
1Cooperative Research Centre for Eye Research and Technology, Sydney, NSW, Australia.
Purpose:
The aim was to examine the interaction of lactoferrin with gram-negative bacteria isolated from ocular adverse responses.
Methods:
Strains representing the species Pseudomonas aeruginosa (six strains), Aeromonas hydrophila, Escherichia coli, Stenotrophomonas maltophilia, and Haemophilus influenza were tested. A modified enzyme-linked immunosorbent assay was used to measure the binding of the strains to native and deglycosylated lactoferrin. The effect on the viability of strains was measured by incubating strains in media containing lactoferrin as the sole carbon and nitrogen source. Siderophore production by strains was measured using an established assay.
Results:
All the strains except the single strain of E. coli (Ecol8) were capable of binding to lactoferrin. The ocular isolate of H. influenzae showed strong affinity for lactoferrin. The P. aeruginosa strains and the strain of S. maltophilia showed significantly reduced (80%-100% reduction; P<0.05) binding to lactoferrin that had been enzymatically deglycosylated, whereas deglycosylation had no effect on the binding of other strains/species tested. Most strains were able to grow and produce siderophores in the presence of lactoferrin as the sole carbon and nitrogen source.
Conclusions:
The ability to bind to and grow on lactoferrin can be important for gram-negative pathogens that colonize the ocular environment, because this could allow bacteria to survive and propagate in the presence of tear fluid.
Insights
Gram-negative bacteria, common in eye infections, can bind to lactoferrin. This interaction may help pathogens survive in the eye by utilizing lactoferrin for growth.
Area of Science:
- Ocular microbiology
- Bacterial pathogenesis
- Host-pathogen interactions
Background:
- Lactoferrin is a key component of innate immunity found in mucosal secretions, including tears.
- Gram-negative bacteria are frequently implicated in ocular infections and adverse responses.
Purpose of the Study:
- To investigate the binding interactions between lactoferrin and clinically relevant gram-negative bacteria from ocular infections.
- To assess the impact of lactoferrin binding on bacterial viability and growth.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) was employed to quantify bacterial binding to native and deglycosylated lactoferrin.
- Bacterial growth and siderophore production were measured in media with lactoferrin as the sole nutrient source.
Main Results:
- Most tested gram-negative bacteria, including Pseudomonas aeruginosa and Haemophilus influenzae, bound to lactoferrin.
- Deglycosylation of lactoferrin significantly reduced binding for P. aeruginosa and Stenotrophomonas maltophilia.
- Many bacterial strains could utilize lactoferrin as a sole carbon and nitrogen source for growth and siderophore production.
Conclusions:
- Bacterial adherence to lactoferrin may be a survival mechanism for gram-negative pathogens in the ocular environment.
- The ability to bind and metabolize lactoferrin could facilitate bacterial colonization and persistence in tear fluid.
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