The high PMNs phagocytosis resistance of enterococcal isolates from RTx patients

Area of Science:

• Microbiology
• Immunology
• Infectious Diseases

Background:

• Opportunistic enterococcal infections pose significant challenges, particularly in immunocompromised individuals.
• Limited symptomatic presentation in these patients complicates diagnosis and management.
• Enterococci are a common cause of hospital-acquired infections.

Purpose of the Study:

• To compare the phagocytosis resistance of commensal enterococcal strains versus isolates from renal transplant (RTx) recipients.
• To investigate the impact of environmental factors (temperature, immunosuppression) on enterococcal resistance.

Main Methods:

• Enterococcal isolates from RTx patients and healthy volunteers were cultured under various conditions (37°C, 42°C, with immunosuppressant).
• Bacterial cells were incubated with polymorphonuclear leukocytes (PMNs).
• Phagocytosis resistance was quantified using flow cytometry to measure PMN mean fluorescence intensity (MFI).

Main Results:

• Enterococcal isolates from RTx patients exhibited significantly higher resistance to PMN phagocytosis compared to commensal strains.
• This increased resistance was observed across different culture conditions, including elevated temperatures and the presence of immunosuppressants.
• Commensal enterococci were less resistant to phagocytosis under all tested conditions.

Conclusions:

• Immunocompromised patients, specifically RTx recipients, are colonized by enterococcal strains with enhanced resistance to host immune defenses (phagocytosis).
• These high-risk strains may contribute to the development of invasive enterococcal infections in susceptible individuals.
• Understanding strain-specific resistance mechanisms is crucial for managing infections in immunocompromised populations.