Impact of Attachment to a Surface on Macrophage Engulfment of Nosocomial Pathogens: Insights into Immune Evasion Mechanisms

Authors: Bharti Sharma, Cláudia Marques, Karin Sauer

Field of Study: Health and Wellness

Program Affiliation: Marques Lab

Faculty Mentors: Cláudia Marques

Easel: 58

Timeslot: Midday

Abstract: Implantable medical devices have transformed personalized medicine but are often compromised by bacterial infections linked to biofilms, which are antibiotic-tolerant. This study aimed to assess the ability of macrophages to engulf Pseudomonas aeruginosa and Staphylococcus aureus under different multiplicities of infection (MOIs) and conditions. Experiments involved challenging differentiated THP-1 monocytes with planktonic bacteria and introducing macrophages to surfaces with attached bacteria. Various bacterial concentrations (10, 102, 103, and 104 cells) were tested, and after two hours, the engulfed bacteria were quantified using cell viability and microscopy. Results showed a direct correlation between planktonic bacterial concentration and macrophage engulfment, with P. aeruginosa being engulfed more readily than S. aureus. However, when bacteria were pre-attached to surfaces, no engulfment occurred, highlighting bacteria's resilience once associated with surfaces or devices.