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In vivo evidence that bacteria in urinary tract infection grow under iron-restricted conditions
Abstract:
The outer membrane protein composition of bacteria isolated directly and without subculturing from the urine of two patients with urinary tract infections was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results indicated that the bacteria grew under iron-restricted conditions, as revealed by the expression of several high-molecular-weight outer membrane proteins which could also be observed when the same isolates were grown under iron-depleted conditions in laboratory media. The antigenicity of outer membrane components of the bacteria isolated was studied by immunoblotting with serum samples from the patients. The results indicated that the sera from the patients contained antibodies against major outer membrane components of the bacteria present in the urine, including the iron-regulated membrane proteins.
Insights
Bacteria from urinary tract infections express iron-regulated outer membrane proteins. Patient antibodies target these bacterial components, indicating an immune response to iron-restricted growth conditions.
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- Urinary tract infections (UTIs) are common bacterial infections.
- Bacterial outer membrane proteins play crucial roles in pathogenesis and host interaction.
- Iron availability significantly influences bacterial gene expression and virulence.
Purpose of the Study:
- To investigate the outer membrane protein composition of bacteria directly isolated from UTI patients.
- To determine if these bacteria exhibit characteristics of growth under iron-restricted conditions.
- To assess the antigenicity of bacterial outer membrane components against patient antibodies.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein analysis.
- Culturing bacteria under iron-depleted laboratory conditions for comparison.
- Immunoblotting using patient serum samples to detect antibody responses.
Main Results:
- Bacteria isolated directly from urine expressed high-molecular-weight outer membrane proteins, indicative of iron-restricted growth.
- These iron-regulated outer membrane proteins were also observed when isolates were grown in iron-depleted media.
- Patient sera contained antibodies against major outer membrane components, including iron-regulated proteins.
Conclusions:
- Bacteria causing UTIs in these patients likely experience iron-restricted conditions in vivo.
- Iron-regulated outer membrane proteins are significant targets for the host immune response during UTIs.
- Understanding these bacterial adaptations and immune responses can inform future therapeutic strategies.