Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens
The aim of this study was to compare the abilities of various urease-positive species to encrust and block catheters with crystalline biofllm. Experiments were performed in laboratory models of the catheterised bladder infected with a range of urease- producing species. The results of these experime...
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Cardiff University
2007
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616.9 Broomfield, Robert James Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
description |
The aim of this study was to compare the abilities of various urease-positive species to encrust and block catheters with crystalline biofllm. Experiments were performed in laboratory models of the catheterised bladder infected with a range of urease- producing species. The results of these experiments allowed the classification of the bacteria into three groups: rapid encrusters, slow encrusters and non-encrusters. Rapid encrusters (<italic>Pr. mirabilis, Proteus vulgaris</italic> and <italic>Providencia rettgeri</italic>) were able to raise the urinary pH to 8 - 9 and cause catheter blockage within 37 h. Slow encrusters (<italic>Morganella morganii, Staphylococcus aureus</italic> and <italic> Staphylococcus saprophytics</italic>) were able to raise the urinary pH moderately (from 6.1 to 6.89 - 7.39 over 96 h) and cause the formation of some encrustation on the catheters. Non- encrusters {<italic>Providencia stuartii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens, Enterobacter cloacae, Citrobacter freundii</italic> and <italic>Citrobacter koseri</italic>) were not able to raise the mean urinary pH above mean levels of 6.45 and did not form crystalline biofilm. <italic>Pr. mirabilis, Pr. vulgaris </italic> and <italic>Pv. rettgeri</italic> were also capable of rapidly encrusting silver-hydrogel coated latex catheters (Bard I.C. catheter) and nitrofurazone impregnated silicone catheters (Rochester NF catheter). There were no significant differences between the times these organisms took to block these catheters compared to all-silicone control catheters. The antimicrobial catheters also had no effect on the urinary pH generated by these organisms. The insensitivity of the three encrusting species to nitrofurazone (MICs 32- 128 ug/ml) is clearly a major factor in the failure of these catheters to prevent encrustation. The results of experiments in which the balloons of all-silicone catheters were inflated with solutions of triclosan (3 mg/ml in 0.1 M sodium carbonate) confirmed previous observations that catheter encrustation by <italic>Pr. mirabilis</italic> was prevented by this strategy. It also proved effective against <italic>Pr. vulgaris</italic>. In both cases, in contrast to the controls, the numbers of viable cells recovered from the residual urine fell steeply within 24 h, the pH of the urine dropped below its nucleation pH (pH 6.5) and the catheters drained freely for the seven day experimental period. The effect of triclosan on encrustation by Pv. rettgeri was minimal however, with no significant difference between blockage times or urinary pHs in the test and control models. While the Proteus sp. had MICs of triclosan of < 0.2 ug/ml, the value for <italic>Pv. rettgeri</italic> was 64 ug/ml. Inflating catheter balloons with a solution which generated nitric oxide proved ineffective as a means of controlling catheter encrustation. Previous studies have shown that a simple cellulose acetate / bromothymol blue sensor is capable of signalling infection by <italic>Pr. mirabilis</italic> and the early stages of catheter encrustation. Placed in the drainage bag it can give early warnings to patients, carers and nurses that catheters need to be replaced. While the use of the sensor in this way could avoid the clinical crises induced by catheter blockage, it would be of more value if an effective strategy to inhibit encrustation could be deployed when the problem is signalled. In the present study it was demonstrated that strips of the sensor polymer placed in the drainage bags changed from yellow to blue signalling the rise in urinary pH induced by infection with <italic>Pr. mirabilis, Pr. vulgaris</italic> or <italic>Pv. rettgeri </italic>. Electron microscopy confirmed that encrustation had started on the catheters at the times the sensors turned blue. Triclosan (3 mg/ml) introduced into the catheter balloons when the signal was observed was found to halt the development of the Proteus crystalline biofilms. It was concluded that an integrated sensor / modulator strategy was feasible for the control of encrustation by these species. (Abstract shortened by UMI.). |
author |
Broomfield, Robert James |
author_facet |
Broomfield, Robert James |
author_sort |
Broomfield, Robert James |
title |
Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
title_short |
Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
title_full |
Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
title_fullStr |
Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
title_full_unstemmed |
Crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
title_sort |
crystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogens |
publisher |
Cardiff University |
publishDate |
2007 |
url |
http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.584062 |
work_keys_str_mv |
AT broomfieldrobertjames crystallinebacterialbiofilmformationonurinarycathetersbyureaseproducingurinarytractpathogens |
_version_ |
1716780376920162304 |
spelling |
ndltd-bl.uk-oai-ethos.bl.uk-5840622015-03-20T03:22:25ZCrystalline bacterial biofilm formation on urinary catheters by urease producing urinary tract pathogensBroomfield, Robert James2007The aim of this study was to compare the abilities of various urease-positive species to encrust and block catheters with crystalline biofllm. Experiments were performed in laboratory models of the catheterised bladder infected with a range of urease- producing species. The results of these experiments allowed the classification of the bacteria into three groups: rapid encrusters, slow encrusters and non-encrusters. Rapid encrusters (<italic>Pr. mirabilis, Proteus vulgaris</italic> and <italic>Providencia rettgeri</italic>) were able to raise the urinary pH to 8 - 9 and cause catheter blockage within 37 h. Slow encrusters (<italic>Morganella morganii, Staphylococcus aureus</italic> and <italic> Staphylococcus saprophytics</italic>) were able to raise the urinary pH moderately (from 6.1 to 6.89 - 7.39 over 96 h) and cause the formation of some encrustation on the catheters. Non- encrusters {<italic>Providencia stuartii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens, Enterobacter cloacae, Citrobacter freundii</italic> and <italic>Citrobacter koseri</italic>) were not able to raise the mean urinary pH above mean levels of 6.45 and did not form crystalline biofilm. <italic>Pr. mirabilis, Pr. vulgaris </italic> and <italic>Pv. rettgeri</italic> were also capable of rapidly encrusting silver-hydrogel coated latex catheters (Bard I.C. catheter) and nitrofurazone impregnated silicone catheters (Rochester NF catheter). There were no significant differences between the times these organisms took to block these catheters compared to all-silicone control catheters. The antimicrobial catheters also had no effect on the urinary pH generated by these organisms. The insensitivity of the three encrusting species to nitrofurazone (MICs 32- 128 ug/ml) is clearly a major factor in the failure of these catheters to prevent encrustation. The results of experiments in which the balloons of all-silicone catheters were inflated with solutions of triclosan (3 mg/ml in 0.1 M sodium carbonate) confirmed previous observations that catheter encrustation by <italic>Pr. mirabilis</italic> was prevented by this strategy. It also proved effective against <italic>Pr. vulgaris</italic>. In both cases, in contrast to the controls, the numbers of viable cells recovered from the residual urine fell steeply within 24 h, the pH of the urine dropped below its nucleation pH (pH 6.5) and the catheters drained freely for the seven day experimental period. The effect of triclosan on encrustation by Pv. rettgeri was minimal however, with no significant difference between blockage times or urinary pHs in the test and control models. While the Proteus sp. had MICs of triclosan of < 0.2 ug/ml, the value for <italic>Pv. rettgeri</italic> was 64 ug/ml. Inflating catheter balloons with a solution which generated nitric oxide proved ineffective as a means of controlling catheter encrustation. Previous studies have shown that a simple cellulose acetate / bromothymol blue sensor is capable of signalling infection by <italic>Pr. mirabilis</italic> and the early stages of catheter encrustation. Placed in the drainage bag it can give early warnings to patients, carers and nurses that catheters need to be replaced. While the use of the sensor in this way could avoid the clinical crises induced by catheter blockage, it would be of more value if an effective strategy to inhibit encrustation could be deployed when the problem is signalled. In the present study it was demonstrated that strips of the sensor polymer placed in the drainage bags changed from yellow to blue signalling the rise in urinary pH induced by infection with <italic>Pr. mirabilis, Pr. vulgaris</italic> or <italic>Pv. rettgeri </italic>. Electron microscopy confirmed that encrustation had started on the catheters at the times the sensors turned blue. Triclosan (3 mg/ml) introduced into the catheter balloons when the signal was observed was found to halt the development of the Proteus crystalline biofilms. It was concluded that an integrated sensor / modulator strategy was feasible for the control of encrustation by these species. (Abstract shortened by UMI.).616.9Cardiff Universityhttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.584062http://orca.cf.ac.uk/54619/Electronic Thesis or Dissertation |