Multiple-Locus Variable-Number Tandem Repeat Analysis Genotyping of Biofilm-Producing Pseudomonas aeruginosa Clinical Isolates

Background: Pseudomonas aeruginosa (P. aeruginosa) significantly contributes to hospital-acquired infections. Objectives: This study aimed to investigate the genetic diversity of P. aeruginosa strains using multiple-locus variable-number tandem repeat analysis (MLVA) and to explore the relationship between biofilm production and antibiotic resistance. Methods: In this cross-sectional study, 79 P. aeruginosa isolates were collected. Antibiotic sensitivity was tested using the Kirby-Bauer method, and biofilm production capability was assessed through the microtiter plate method. Genetic diversity was evaluated by MLVA, analyzing eight variable-number tandem repeat (VNTR) loci: MS-213, MS-214, MS-207, MS-217, MS-222, MS-209, MS-77, and MS-172. Phylogenetic relationships were delineated using PHYLOViZ 2.0 software. Results: The patient cohort comprised 51.9% males, with the majority of samples (35.4%) obtained from urine. Ceftazidime (CAZ 30µg) showed the highest resistance rate at 77.2%. Notably, 92.4% of isolates were capable of forming biofilms, categorized as 22.7% weak, 28.7% moderate, and 46.5% strong. Phylogenetic analysis demonstrated variability across one or more VNTR loci. Simpson’s index (0.906) and Shannon-Weiner diversity indices (H: 3.466, J: 0.910, Hmax: 3.807, Hmin: 1.242) identified MS77 as the most informative marker for genetic diversity among the isolates. Conclusions: The study highlights an alarming trend in antibiotic resistance, underscoring the necessity of regular monitoring. The findings confirm that MLVA is a straightforward, rapid genotyping method suitable for assessing the genetic diversity of P. aeruginosa.