The resistance of urinary tract pathogens to chlorhexidine bladder washouts

Isolates of Providencia stuartii, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae and Streptococcus faecalis from urinary-tract infections in spinally-injured patients together with Escherichia coli 10418 were challenged with chlorhexidine (200 mg l-1) in a model of a catheterized bladder under conditions which simulate the bladder washout technique. All species survived the antiseptic. Organisms growing on the wall of the bladder model appeared to be particularly resistant and electron microscopy showed that these cells were embedded in a protective glycocalyx. The effect of chlorhexidine bladder washouts on the bacterial flora in the urine of patients was also observed and shown to be minimal and temporary. Examination of urinary sediments from patients revealed the presence of micro-colonies of bacteria embedded in a polysaccharide matrix. We conclude that bladder washouts with chlorhexidine are not likely to eliminate established infections with organisms that occur in patients with indwelling bladder catheters.