Clinical Microbiology and Antimicrobial Chemotherapy. 2019; 21(1):75-80
To study the colonization activity of clinical strains of uropathogenic Escherichia coli (UPEC) against various types of urological catheters.
Biofilms of E. coli (n = 6) were formed for 24 h according to the standard method. Urological catheters made from latex, polyvinylchloride, silicon and silver-coated silicon were used as a surface for bacterial colonization. The surface roughness and hydrophobicity, biofilm mass, number of colony forming units in biofilm, and frequency of conjugation were assessed.
The number of E. coli cells adhered on different surfaces after 2 h of incubation varied from 10E + 02 to 10E + 04 CFU/ml/cm2 and was not significantly different between the catheters types. After 6 h of incubation, the number of attached bacteria was increased by an order of magnitude for all catheter types. This trend was consistent throughout the 24 h across all materials (W-test: p = 0.001), with the exception of silver-coated silicone where the number of viable bacteria was lower compared to that after the 6-hour colonization. Over the period of 2-6 h, the bacterial growth rate was increasing with an increase in the catheter’s roughness, and over the period of 6-24 h, the significant inverse relationship was observed. There was a positive correlation between the biomass of the 24-hour biofilm and the catheter’s hydrophobicity (Rs = 0.69; р<0.05). A decrease in the frequency of horizontal gene transfer within the biofilm on a silver-coated catheter was also found.
An addition of silver ions into the silicone surface did not inhibit bacterial adhesion, but reduced cell viability at the advanced stages of biofilm formation. The use of silver coating may be a way to reduce the incidence of catheter-associated UTI through suppression of bacterial conjugation and survival when urinary catheters are used for a long-term period.