Investigation of Antibacterial Activity and Biofilm Formation of Silicones Coated With Minocycline-Rifampicin, Silver Nitrate, and Nitrofurantoin for Short-term Utilization in In Vitro Urinary System Models.

Salvarci, Ahmet; Koroglu, Mehmet; Erayman, Berna

OBJECTIVE To analyze antimicrobial activity and biofilm formation on silicones coated with antimicrobial substances in in vivo short-term catheterization simulation using our newly developed in vitro urinary system model and to compare minocycline-rifampin (MR)-, silver nitrate-, and nitrofurantoin (NF)-coated silicone discs. MATERIALS AND METHODS Silicone discs were exposed to bacterial urine suspension for 168 hours. The antimicrobial activities were assessed in the medium, and the inhibition zone diameters were measured. The weight of the silicones was measured for biofilm growth assessment before and after the experiment, and confocal microscopy images were taken. RESULTS Although the inhibition zone diameters of silver nitrate silicones were larger than those of pure silicone (PS), MR, and NF silicones, biofilm formation could not be prevented (P < .05). MR and NF silicones were superior to PS in terms of antimicrobial efficacy and prevention of biofilm formation (P < .05). In terms of biofilm prevention, no differences were detected between NF and MR silicones apart from a slightly superior ability of MR silicones to inhibit Escherichia coli (P > .05). Biofilm formation occurred on all silicone discs. CONCLUSION In short-term urinary catheter utilization, antimicrobial efficacy and biofilm formation prevention were superior in coated silicones, regardless of the type of antibiotic used, compared with the control group (PS). As the study was conducted in an in vitro setting, the findings should be substantiated with in vivo studies on the grounds that different results may be obtained in these settings.