Vol. 9, Issue 11, Part A (2025)

Biofilm formation plays a crucial role in protecting microorganisms from the host immune system, facilitating their persistence and contributing to chronic infections with high resistance to antimicrobials. This study evaluated biofilm formation in 20 Pseudomonas aeruginosa isolates using three methods: Tube method, Congo red agar method, and Microtitre plate method. The Tube method identified biofilm formation in 18 (90%) isolates, categorizing 3 as strong, 9 as moderate, and 6 as weak biofilm producers, while 2 isolates were non-producers. The Congo red method detected biofilm formation in all 20 (100%) isolates, with 4 strong, 7 moderate, and 9 weak biofilm producers. Similarly, the Microtitre plate method also confirmed biofilm formation in all isolates, identifying 3 strong, 6 moderate, and 11 weak biofilm producers. Additionally, quorum sensing, a key regulatory mechanism for virulence, biofilm formation, and antibiotic resistance in P. aeruginosa, was investigated by screening for lasI and lasR genes using Polymerase Chain Reaction. Both genes, with amplicon sizes of 295 bp and 130 bp, were detected in 14 isolates. The highest occurrence of Quorum sensing genes was observed in isolates from cutting board swabs, followed by chicken meat (64.28%) and knife swabs (50%). Antimicrobial resistance profiling of all isolates against 12 antibiotics revealed the highest resistance to tetracycline (95%), followed by cefotaxime (85%). Conversely, imipenem demonstrated the highest sensitivity (75%).

These findings underscore the high biofilm-forming capacity, prevalence of quorum sensing genes, and substantial antimicrobial resistance among P. aeruginosa isolates, highlighting their potential to contribute to persistent infections and treatment challenges.