Effects of azithromycin on Pseudomonas aeruginosa isolates from catheter-associated urinary tract infection

Pseudomonas aeruginosa is a common pathogenic bacterium in urinary tract infections (UTIs), particularly catheter-associated UTIs. The aim of this study was to investigate the effect of azithromycin (AZM) on P. aeruginosa isolated from UTIs. Isolates were identified by biochemical assays and the Vitek system. Antimicrobial susceptibility was determined using the disk diffusion assay. Biofilm formation and adhesion were assayed using a crystal violet staining method. The swimming motility was assayed on agar plates. The elastase activity and rhamnolipid production were determined by the elastin-Congo red method and orcinol reaction, respectively. A total of 32 bacterial isolates were collected from 159 urinary catheters and eight of them were P. aeruginosa isolates. The results showed that the P. aeruginosa isolates had stronger biofilm formation capability and the biofilms were thicker than those of P. aeruginosa PAO1. AZM inhibited biofilm formation and adhesion on urinary catheters, and also decreased swimming motility and the production of virulence factors. The results of this study indicated that AZM is potentially a good choice for use in the treatment of UTIs.