Phenotypic Characterization and Molecular Identification of Pseudomonas aeruginosa Isolated from Clinical Samples

Abstract

Pseudomonas aeruginosa is an important opportunistic pathogen associated with diverse clinical infections. This study aimed to isolate and phenotypically characterize P. aeruginosa from clinical samples collected from dogs with dermatological conditions and to isolate and identify using molecular methods. Fifty clinical samples comprising wound, pus, otitis externa, and dermatitis swabs were collected during April–May 2025. Samples were enriched in BHI broth, cultured on cetrimide agar, and presumptive isolates were assessed using cultural and microscopic characteristics. All presumptive isolates were subsequently subjected to PCR amplification targeting the 16S rRNA and rpoB genes. Five presumptive P. aeruginosa isolates were recovered from the 50 samples, corresponding to an isolation frequency of 10.0% (5/50). The isolates exhibited cultural and microscopic characteristics consistent with P. aeruginosa, including characteristic colony morphology, pigmentation, fluorescence under ultraviolet illumination, and Gram-negative rod-shaped morphology. PCR amplification produced the expected 618 bp 16S rRNA and 759 bp rpoB amplicons in all five isolates. These findings indicate that conventional phenotypic characterisation combined with dual-target PCR can provide practical molecular support for the identification of presumptive P. aeruginosa isolates from canine dermatological clinical samples.