Effect of temperature on the shift of Pseudomonas fluorescens from an environmental microorganism to a potential...

Area of Science:

• Microbiology
• Immunology
• Pathogen Research

Background:

• Pseudomonas fluorescens is a Gram-negative bacterium typically associated with low-temperature environments.
• Increasingly isolated as a cause of nosocomial infections, its virulence at human physiological temperatures is a growing concern.
• Previous studies suggest human body temperature may not inhibit its growth, necessitating further investigation.

Purpose of the Study:

• To investigate the in vitro virulence of Pseudomonas fluorescens at different temperatures relevant to human infection.
• To assess the adherence and biofilm formation capabilities of P. fluorescens grown at 28°C versus 37°C.
• To examine the induction of host inflammatory responses by P. fluorescens at varying temperatures.

Main Methods:

• Culturing Pseudomonas fluorescens at 28°C and 37°C.
• Assessing bacterial adherence to human A549 pulmonary cells.
• Evaluating biofilm formation capacity.
• Measuring the expression of proinflammatory cytokines, beta-defensin 2, and intercellular adhesion molecule-1.

Main Results:

• Pseudomonas fluorescens induced inflammatory mediators when grown at 28°C.
• Biofilm formation by P. fluorescens was observed exclusively at 37°C.
• Adherence to pulmonary cells occurred at both temperatures, but biofilm formation was temperature-dependent.

Conclusions:

• Pseudomonas fluorescens exhibits distinct virulence strategies depending on growth temperature.
• The ability to form biofilms at human physiological temperature (37°C) highlights its potential as an opportunistic pathogen.
• Further research is crucial to understand the full virulence spectrum of P. fluorescens in clinical settings.