Fifty Foley bladder catheters that had been indwelling for periods ranging from 3 to 83 days (mean 35 days) were examined for the presence of bacterial biofilm. Scanning electron microscopy on freeze-dried cross-sections and fixed, critical point-dried longitudinal sections revealed biofilm formation on the luminal surfaces of 44 of the catheters. Culture of urine samples and sonicates from catheters revealed that the prevalence of bacteriuria was less than that of catheter colonization. A wide range of nosocomial species were found colonizing the catheters, Escherichia coli being most often isolated. The bacterial composition of the biofilms ranged from single species to mixed communities containing up to four species. There was no relationship between the length of time that the catheter had been in situ and the extent of biofilm formation. The biofilms varied in thickness from 3 to 490 microns and were visible as layers of bacterial cells up to about 400 cells deep, embedded in a matrix.

An increased risk of bladder cancer is a recognized complication in spine-injured patients undergoing long-term urethral catheterization to preserve renal function. Aerobic cultures from 28 of 30 paraplegic patients showed complex bacterial flora containing nitrate-reducing organisms (Escherichia coli, Proteus and Klebsiella spp.). Urine samples from 29 paraplegic patients were also found to contain volatile nitrosamines. Mean N-nitrosamine excretion levels were 0.65 +/- 0.69 micrograms/day N-nitrosodimethylamine, 0.25 +/- 0.44 micrograms/day N-nitrosopiperidine and 0.39 +/- 0.50 micrograms/day N-nitrosopyrrolidine. A mean urinary nitrite excretion of 10.4 +/- 13.2 mg/day was found in 24 out of 30 paraplegic patients. In the sterile urine of control volunteers (medical staff attending the paraplegic patients and in-patients from other wards of the hospital), no urinary excretion of volatile N-nitrosamines and nitrite was found. The results clearly demonstrate a bacterially mediated in vivo formation of N-nitroso compounds in the urinary tracts of paraplegic patients which may be an important etiological risk factor for bladder cancer in this patient group.

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✓ Intracranial pressure (ICP) was monitored continuously for 48 to 72 hours in 12 patients with dementia and communicating hydrocephalus, to see if this would help determine which patients might benefit from surgical shunting of CSF, since not all such patients respond to treatment. Patients who showed variability of ICP improved following surgery, while patients with consistently flat ICP tracings did not. It is suggested that continuous monitoring of ICP may help identify cases suitable for surgery.