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The effect of growth conditions on in vitro adherence, invasion, and NAF expression by Proteus mirabilis 7570
R K Latta1, M J Schur, D L Tolson
1Institute for Biological Sciences, National Research Council Canada, Ottawa. roger.latta@nrc.ca
Abstract:
Proteus mirabilis is a common cause of upper urinary tract infections. Fimbriae-mediated adherence of this organism to urinary tract epithelium and invasion of host cells are factors thought to be important in its pathogenesis. We have assessed the effect of growth in serum, blood, and urine on the ability of P. mirabilis 7570 to adhere to and invade in vitro the cell line EJ/28, derived from a human urinary tract tumour, and to express nonagglutinating fimbriae (NAF). Proteus mirabilis was capable of adhering to EJ/28 cells to varying degrees depending upon the growth conditions used. It was invasive under all conditions, except when grown in urine, and was found to be particularly so when serum or blood was present in the media. Expression of NAF occurred under all growth conditions examined and was limited only by a decrease in temperature.
Insights
Proteus mirabilis causes urinary tract infections by adhering to and invading host cells. Its ability to invade is reduced when grown in urine but enhanced by serum or blood, impacting pathogenesis.
Area of Science:
- Microbiology
- Urology
- Pathogenesis
Background:
- Proteus mirabilis is a frequent cause of upper urinary tract infections.
- Fimbriae-mediated adherence and host cell invasion are key virulence factors.
- Understanding environmental influences on these factors is crucial for infection control.
Purpose of the Study:
- To investigate how growth conditions (serum, blood, urine) affect P. mirabilis adherence and invasion.
- To determine the impact of these conditions on nonagglutinating fimbriae (NAF) expression.
- To correlate in vitro findings with potential in vivo pathogenesis.
Main Methods:
- Culturing P. mirabilis 7570 in media supplemented with serum, blood, or urine.
- Assessing bacterial adherence to the EJ/28 human urinary tract cell line.
- Quantifying bacterial invasion into EJ/28 cells.
- Analyzing nonagglutinating fimbriae (NAF) expression under different growth conditions.
Main Results:
- P. mirabilis exhibited variable adherence to EJ/28 cells based on growth media.
- Invasion occurred under all conditions except when bacteria were grown in urine.
- Serum and blood significantly enhanced P. mirabilis invasion.
- NAF expression was observed across all tested conditions, limited only by reduced temperature.
Conclusions:
- Growth conditions, particularly the presence of serum or blood, significantly modulate P. mirabilis virulence factors.
- The urinary environment appears to attenuate bacterial invasion capabilities.
- These findings provide insights into the pathogenesis of Proteus mirabilis urinary tract infections.