Phenotypic Diversity of Biofilm Formation and Molecular Detection of Selected Biofilm Associated Genes in Pseudomonas aeruginosa

Open Access

Abstract

Background: Pseudomonas aeruginosa is an important opportunistic pathogen in which biofilm formation contributes to persistence, chronic infection, and reduced antimicrobial susceptibility. Phenotypic variation and differences in biofilm-associated genetic determinants may influence the biological behavior of clinical isolates. Aim of the study: To characterize the phenotypic diversity of biofilm formation and detect selected biofilm-associated genes among clinical P. aeruginosa isolates. Methods & Materials: A cross-sectional observational study was conducted at the Department of Microbiology, Mymensingh Medical College, Bangladesh, from March 2025 to February 2026. Sixty-eight non-duplicate clinical P. aeruginosa isolates recovered from wound, aural, urine, and blood specimens were consecutively included. Biofilm formation was assessed using a standardized microtiter plate crystal-violet assay and categorized as non-, weak, moderate, or strong production. PCR was performed to detect pqsA, lasB, and lasR. Data were analyzed using SPSS version 26.0, with categorical association assessed using chi-square or Fisher's exact tests. Result: Wound swabs were the predominant source of isolates (67.65%), followed by aural swabs (14.71%), urine (11.76%), and blood (5.88%). Biofilm production was detected in 58.82% of isolates, comprising 8.82% weak, 23.53% moderate, and 26.47% strong producers. Moderate and strong phenotypes together accounted for 50.00% of isolates. Biofilm phenotype was not significantly associated with clinical specimen type (χ²=4.62, p=0.593). pqsA was detected in 100.00% of isolates, whereas lasB was present in 77.94% and lasR was absent in all isolates. lasB positivity increased across non-producer, weak, and moderate phenotypes, whereas pqsA remained uniformly detected. Conclusion: P. aeruginosa isolates demonstrated substantial phenotypic heterogeneity in biofilm formation and distinct molecular profiles of selected biofilm-associated genes. Integrating phenotypic biofilm assessment with targeted molecular characterization may provide a more informative approach to understanding biofilm-associated persistence in clinical isolates.