D Stickler | PubMed Health

PubMed1992

Scanning electron microscopy of bacterial biofilms on indwelling bladder catheters.

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.

Bacterial Adhesion↗

PubMed1992

Virulence factors in Escherichia coli from urinary tract infections in patients with spinal injuries.

A collection of 70 strains of Escherichia coli from urinary tract infections in spine-injured patients undergoing long-term bladder catheterization were tested for characteristics that have been associated with the ability to produce pyelonephritis. The incidence of the virulence factors were: mannose-resistant haemagglutinins (30%), P-fimbriae (17%), haemolysin (27%), K-antigens (28%) and aerobactin (by bioassay 33%, by gene probe 39%). Only 54% of the strains belonged to the O-serotypes usually associated with urinary tract infections. E. coli carrying the full complement of virulence factors were rare in the urinary tract of the spinal patients and were not associated with episodes of symptomatic pyelonephritis. It is clear that the neuropathic bladder and the presence of the catheter permits a wide variety of bacterial types to colonize the urinary tract and cause infection of the kidney. The identification of host markers rather than bacterial factors is suggested as a more fruitful approach to the early detection of cases likely to progress to pyelonephritis in this group of patients.

Cross Infection↗

PubMed1991

Activity of antiseptics against biofilms of mixed bacterial species growing on silicone surfaces.

As part of a programme to establish the relative merits of antiseptics that are used as bladder instillations to control urinary tract infections in patients with indwelling catheters, the activity of five such formulations were tested against dense (10(9) cfu/cm2) mixed biofilms composed of Citrobacter diversus, Pseudomonas aeruginosa and Enterococcus faecalis growing on silicone discs. All three species were resistant to chlorhexidine (200 mg/l) and povidone-iodine (1% v/v) in the biofilm mode of growth, whereas these agents rapidly eliminated viable cells from urine suspensions of the mixed community. Lactic acid (1% v/v) produced a 1 log reduction of the biofilm population within 30 min of exposure. The mandelic acid (1% w/v) and mandelic acid (0.5% w/v)/lactic acid (0.5% v/v) mixture proved to be the most effective in eliminating the biofilm organisms. It is suggested that these latter solutions should now be tested for efficacy in bladder washouts against urinary tract infections in catheterized patients.

Anti-Infective Agents, Urinary↗

PubMed1991

Activity of some antiseptics against urinary tract pathogens growing as biofilms on silicone surfaces.

The activity of chlorhexidine, mandelic acid and a mandelic/lactic mixture were tested against biofilms of four species of gram-negative nosocomial organisms that commonly infect the catheterized urinary tract. Cells growing on silicone discs were exposed to concentrations of agents used in bladder instillation. Citrobacter diversus biofilms proved to be sensitive to all three agents. Pseudomonas aeruginosa, Proteus mirabilis and Klebsiella pneumoniae all survived well in chlorhexidine but their viability was significantly reduced by the mandelic acid formulations. These results suggest that bladder instillations of mandelic acid or mandelic/lactic acids would be more effective than chlorhexidine in eliminating biofilms from catheter surfaces.

Anti-Infective Agents, Urinary↗

PubMed1991

Activity of antiseptics against biofilms of mixed bacterial species growing on silicone surfaces.

As part of a programme to establish the relative merits of antiseptics that are used as bladder instillations to control urinary tract infections in patients with indwelling catheters, the activity of five such formulations were tested against dense (10(9) cfu/cm2) mixed biofilms composed of Citrobacter diversus, Pseudomonas aeruginosa and Enterococcus faecalis growing on silicone discs. All three species were resistant to chlorhexidine (200 mg/l) and povidone-iodine (1% v/v) in the biofilm mode of growth, whereas these agents rapidly eliminated viable cells from urine suspensions of the mixed community. Lactic acid (1% v/v) produced a 1 log reduction of the biofilm population within 30 min of exposure. The mandelic acid (1% w/v) and mandelic acid (0.5% w/v)/lactic acid (0.5% v/v) mixture proved to be the most effective in eliminating the biofilm organisms. It is suggested that these latter solutions should now be tested for efficacy in bladder washouts against urinary tract infections in catheterized patients.

Anti-Infective Agents, Local↗

PubMed1989

Racial differences in optic nerve head parameters.

Results of previous studies have strongly indicated that the prevalence of elevated intraocular pressure is greater in blacks than in whites and that blacks are more susceptible than whites to glaucomatous damage at any given level of pressure. It has also been suggested that a larger disc area might predispose an eye to glaucomatous damage. We investigated the possibility that clinically quantifiable differences might exist in optic disc parameters between normotensive white and black patients. Disc area, cup-to-disc ratio, and cup volume measured with a video-ophthalmograph (Rodenstock Optic Disc Analyzer) were significantly larger in blacks than in whites, while there was no difference in the disc rim area between the two groups. We derived a mathematical model of the optic disc that relates posterior displacement of the lamina cribrosa to the disc area, distensibility of the disc, and intraocular pressure.

Adolescent↗

PubMed1989

Activity of antiseptics against Escherichia coli growing as biofilms on silicone surfaces.

The activity of chlorhexidine, acetic, lactic and mandelic acids were examined against biofilms of Escherichia coli established on silicone discs and against the test strain growing in suspension in urine. The results showed that the concentrations of chlorhexidine and acetic acid normally used for bladder instillations to control infections in patients with indwelling catheters failed to eliminate cells from the biofilm in exposure periods of up to 2 h. Lactic acid (1% v/v) had a bactericidal effect on planktonic cells but poor activity against cells in the biofilm. Mandelic acid (1% v/v), and mandelic (1% v/v) and lactic acid (1% v/v) mixtures eliminated organisms from both suspensions and biofilms. It is suggested that these solutions be considered as alternatives to acetic acid and chlorhexidine for the washing of catheterized bladders.

Acetates↗