Prevalence of the pelA gene in Pseudomonas aeruginosa and serum IL-22 levels in patients with diabetic foot ulcers

Abstract

Objective: Diabetic foot ulcers (DFUs) are a major complication of diabetes mellitus, often complicated by Pseudomonas aeruginosa, a biofilm-forming pathogen associated with delayed wound healing. This study evaluated the prevalence of the pelA gene, a determinant of biofilm production, in P. aeruginosa isolates from DFU patients and assessed systemic immune response through serum interleukin-22 (IL-22) levels.

Methods: A cross-sectional study was conducted from May 2024 to January 2025, including 48 DFU patients and 48 age- and sex-matched healthy controls. Wound swabs were collected from patients, and P. aeruginosa isolates were identified using the VITEK-2 system or PCR amplification of the 16S rRNA gene. The presence of the pelA gene was confirmed by PCR. Serum IL-22 concentrations were measured using ELISA. Data were analysed with SPSS v26, using t-tests or Mann–Whitney U tests as appropriate, with P < 0.05 considered significant.

Results: All 48 P. aeruginosa isolates (100%) carried the pelA gene. Mean serum IL-22 levels were significantly higher in DFU patients compared with healthy controls (31.04 ± 0.22 pg/mL vs. 28.89 ± 0.84 pg/mL; P = 0.015).

Conclusion: The universal detection of pelA highlights its potential as a molecular marker of biofilm-forming P. aeruginosa in DFUs. Elevated IL-22 levels indicate an active host immune response in affected patients. Combined microbial and immunological markers may support improved assessment of infection dynamics in diabetic foot ulcers, although further multicentre and longitudinal studies are warranted.