The Use of Salicylic Acid to Prevent the Adherence of Escherichia Coli to Silastic Catheters

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Abstract
We studied the effect of salicylic acid on the attachment of Escherichia coli to silastic catheters. Silastic catheters were exposed to organisms grown in the presence of subinhibitory concentrations (1 and 5 mM.) of salicylic acid. An agar rolling technique demonstrated 59% and 79% inhibition of adherence with the 2 concentrations, respectively. Silastic catheters were also pretreated by heating and then incubating in 200 mM. and 600 mM. salicylic acid in 95% ethanol at -20C. After incubation in 10(4) CFU/ml. E. coli for 5 hours at 37C, 62% and 93% inhibition of adherence was observed. Acetylsalicylic acid and ibuprofen did not demonstrate similar results. Similar inhibition (82% and 95%) was observed despite preincubation of the treated catheters in sterile urine for 4 days. A bioluminescent assay of bacterial adherence also revealed inhibition only with salicylic acid. Studies using 3H-leucine demonstrated a decrease in adherence with higher concentrations of salicylic acid. Finally, tridodecylmethylammonium was used to bind salicylic acid to silastic catheters. After a 5-hour incubation in 10(4) CFU/ml. at 37C, 94% and 99% inhibition were observed with 200 and 600 mM. salicylic acid. Salicylic acid decreases adherence of E. coli to silastic catheters. This observation may be of value in designing catheters less likely to cause urinary tract infection.