Characterisation of Biofilm Production and Carbapenem Resistance Genes in Pseudomonas aeruginosa from Clinical Isolates

Abstract

Background: Pseudomonas aeruginosa is a major opportunistic pathogen frequently isolated from hospitalised patients. Its pathogenicity is attributed to multiple virulence factors, strong biofilm-forming ability, and multidrug resistance. The widespread misuse of antibiotics has further accelerated resistance, increasing morbidity and mortality, particularly among immunocompromised individuals. Objectives: This study aimed to determine the prevalence, antimicrobial resistance profiles, and biofilm-forming capacity of P. aeruginosa isolates obtained from various clinical specimens. Materials and Methods: Eighty clinical specimens (22 wound, 40 burn, and 18 sputum) were collected from patients admitted to Al-Hilla Teaching Hospital between January and March 2024. Bacterial identification was performed using standard microbiological techniques, including colony morphology, Gram staining, and biochemical tests, followed by confirmation with the VITEK-2 Compact system. Biofilm formation was evaluated using the Tissue Culture Plate (TCP) method. Results: Out of 80 samples, 20 (25%) were positive for P. aeruginosa: 5 (25%) from wounds, 9 (45%) from burns, and 6 (30%) from sputum. The highest infection rate occurred among individuals aged 31–40 years (40%), with a female predominance (80%, p = 0.0034). Imipenem and gentamicin exhibited the greatest sensitivity (55%), while cefazolin and tigecycline showed complete resistance (100%). Strong biofilm formation was detected in 45% of isolates, significantly associated with higher resistance levels (p = 0.009).The study shows a high burden of carbapenem resistance in Pseudomonas aeruginosa, with bla-IMP detected in 60% of isolates. The presence of adeB (16/25) and OprD (22/25) indicates multiple, co-existing resistance mechanisms. These combined factors highlight the multifactorial nature of resistance and the need for ongoing molecular surveillance Conclusion: Routine antimicrobial susceptibility testing and biofilm assessment are essential for guiding effective therapy and enhancing infection control strategies against P. aeruginosa.