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Effects of silver on adherence of bacteria to urinary catheters: in vitro studies
M M Gabriel1, A D Sawant, R B Simmons
1Biology Department, Georgia State University, Atlanta 30302-4010.
Abstract:
Strains of Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Enterococcus faecalis, and Klebsiella pneumoniae, mostly from complicated urinary tract infections, showed reduced adherence to silver-treated silicone or latex catheters as compared with latex or silicone catheters. The relative degrees of cell adherence to catheters at 2 h or 18 h, as indicated by radiolabeled cell assays, were in general agreement with growth rate-reduction assays and scanning-electron-microscopy data. For strains of E. coli, the correlation between cell hydrophobicity and degree of adherence to catheters was not significant. Antibiotic resistance (tetracycline, sulfathiazine, neomycin, kanamycin) and silver resistance were not associated. The radiolabel adherence procedure provided a quantitative method for evaluating the relative antimicrobial efficacy of silver-treated catheters.
Insights
Silver-treated catheters significantly reduced bacterial adherence in complicated urinary tract infections. This quantitative method aids in assessing antimicrobial catheter efficacy against common uropathogens.
Area of Science:
- Microbiology
- Biomaterials Science
- Infectious Diseases
Background:
- Catheter-associated urinary tract infections (CAUTIs) are a significant clinical challenge.
- Bacterial adherence to indwelling urinary catheters promotes biofilm formation and infection.
- Novel strategies are needed to prevent CAUTI pathogenesis.
Purpose of the Study:
- To evaluate the efficacy of silver-treated catheters in reducing bacterial adherence.
- To compare adherence of common uropathogens to silver-treated versus non-treated catheters.
- To assess the correlation between bacterial properties and adherence.
Main Methods:
- Utilized radiolabeled cell adherence assays to quantify bacterial attachment to catheters.
- Employed scanning electron microscopy (SEM) for visual assessment of bacterial colonization.
- Conducted growth rate reduction assays to determine antimicrobial activity.
- Tested common uropathogens including Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Enterococcus faecalis, and Klebsiella pneumoniae.
Main Results:
- Silver-treated silicone and latex catheters demonstrated significantly reduced adherence of bacterial strains compared to untreated catheters.
- Adherence reduction was observed for multiple uropathogens commonly associated with complicated urinary tract infections.
- Radiolabeled cell assays, SEM, and growth rate assays showed consistent results regarding adherence and antimicrobial efficacy.
- No significant correlation was found between Escherichia coli hydrophobicity and catheter adherence.
- Antibiotic resistance and silver resistance were not associated in the tested strains.
Conclusions:
- Silver treatment effectively reduces the adherence of key uropathogens to urinary catheters.
- The radiolabel adherence assay is a reliable quantitative method for evaluating antimicrobial catheter efficacy.
- Findings support the use of silver-treated catheters as a strategy to mitigate CAUTIs.