Some observations on the activity of three antiseptics used as bladder irrigants in the treatment of urinary tract infection in patients with indwelling catheters

A comparison has been made of the activity of three antiseptics that are used as bladder irrigants in the treatment of urinary tract infection in catheterised patients. At the concentrations and exposure times used for bladder irrigation, phenoxyethanol (2:4% v/v) proved to be highly bactericidal against urine-grown cells of all the common urinary pathogens tested. Chlorhexidine (200 microgram/ml) was active against Escherichia coli and produced significant reductions in the viability of Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa but failed to eradicate Providencia stuartii. Exposure to noxythiolin (2.5% v/v) for 20 min had little effect in any of the bacteria, even though all strains tested had been recorded as noxythiolin-sensitive by conventional plate sensitivity tests. Contact with noxythiolin for periods of at least 1-2 hrs was necessary before extensive bactericidal activity was detected. These results provide an explanation of the poor clinical performance of noxythiolin that we have observed.