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Developing a real time sensing system to monitor bacteria in wound dressings.

Farrow MJ, Hunter IS, Connolly P - Biosensors (Basel) (2012)

Bottom Line: It is based on impedance sensors that could be placed at the wound-dressing interface and potentially monitor bacterial growth in real time.Impedance was measured using disposable silver-silver chloride electrodes.The main findings were that the impedance profiles obtained by silver-silver chloride sensors in bacterial suspensions could detect the presence of high cell densities.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, University of Strathclyde, Wolfson Centre, Glasgow, G4 0NW, UK. malcolm.farrow@strath.ac.uk.

ABSTRACT
Infection control is a key aspect of wound management strategies. Infection results in chemical imbalances and inflammation in the wound and may lead to prolonged healing times and degradation of the wound surface. Frequent changing of wound dressings may result in damage to healing tissues and an increased risk of infection. This paper presents the first results from a monitoring system that is being developed to detect presence and growth of bacteria in real time. It is based on impedance sensors that could be placed at the wound-dressing interface and potentially monitor bacterial growth in real time. As wounds can produce large volumes of exudate, the initial system reported here was developed to test for the presence of bacteria in suspension. Impedance was measured using disposable silver-silver chloride electrodes. The bacteria Staphylococcus aureus were chosen for the study as a species commonly isolated from wounds. The growth of bacteria was confirmed by plate counting methods and the impedance data were analysed for discernible differences in the impedance profiles to distinguish the absence and/or presence of bacteria. The main findings were that the impedance profiles obtained by silver-silver chloride sensors in bacterial suspensions could detect the presence of high cell densities. However, the presence of the silver-silver chloride electrodes tended to inhibit the growth of bacteria. These results indicate that there is potential to create a real time infection monitor for wounds based upon impedance sensing.

No MeSH data available.


Related in: MedlinePlus

The final cell numbers of RN4220 in the parallel suspension experiment from low starting cell densities. Bar colours indicate sample number: Red—sample one; Blue—sample two; and Yellow—sample three.
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biosensors-02-00171-f004: The final cell numbers of RN4220 in the parallel suspension experiment from low starting cell densities. Bar colours indicate sample number: Red—sample one; Blue—sample two; and Yellow—sample three.

Mentions: The final cell densities of RN4220 after 16 h culture with Ag-AgCl sensors in MHB, MHB with glucose and with pre-washed sensors, showed wide variation, as shown in Figure 4. The control cultures, which contained no sensors, always reached approximately 1 × 109 CFU∙mL−1 within 24 h. Only one of the three vials with sensors in MHB grew to a density in excess of 5 × 107 CFU∙mL−1. In the experiments with added glucose and sensors present, one MHB-0.1% glucose, three MHB-0.2% glucose and one MHB-0.4% glucose vials grew to more than 5 × 107 CFU∙mL−1. For the sensors that were pre-washed before inoculation, only two of the three vials reached densities above 5 × 107 CFU∙mL−1. In total there were 15 RN4220 vials with sensors, and of these 15 it was observed that 8 reached cell densities above 5 × 107 CFU∙mL−1, and the remaining 7 remained below this level. This was evidence that the presence of the Ag-AgCl sensors may have inhibited the RN4220 growth from lower inoculation densities. The level of glucose appears to affect the amount of inhibition, with 0.2% being the optimum to overcome the reduced growth.


Developing a real time sensing system to monitor bacteria in wound dressings.

Farrow MJ, Hunter IS, Connolly P - Biosensors (Basel) (2012)

The final cell numbers of RN4220 in the parallel suspension experiment from low starting cell densities. Bar colours indicate sample number: Red—sample one; Blue—sample two; and Yellow—sample three.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263571&req=5

biosensors-02-00171-f004: The final cell numbers of RN4220 in the parallel suspension experiment from low starting cell densities. Bar colours indicate sample number: Red—sample one; Blue—sample two; and Yellow—sample three.
Mentions: The final cell densities of RN4220 after 16 h culture with Ag-AgCl sensors in MHB, MHB with glucose and with pre-washed sensors, showed wide variation, as shown in Figure 4. The control cultures, which contained no sensors, always reached approximately 1 × 109 CFU∙mL−1 within 24 h. Only one of the three vials with sensors in MHB grew to a density in excess of 5 × 107 CFU∙mL−1. In the experiments with added glucose and sensors present, one MHB-0.1% glucose, three MHB-0.2% glucose and one MHB-0.4% glucose vials grew to more than 5 × 107 CFU∙mL−1. For the sensors that were pre-washed before inoculation, only two of the three vials reached densities above 5 × 107 CFU∙mL−1. In total there were 15 RN4220 vials with sensors, and of these 15 it was observed that 8 reached cell densities above 5 × 107 CFU∙mL−1, and the remaining 7 remained below this level. This was evidence that the presence of the Ag-AgCl sensors may have inhibited the RN4220 growth from lower inoculation densities. The level of glucose appears to affect the amount of inhibition, with 0.2% being the optimum to overcome the reduced growth.

Bottom Line: It is based on impedance sensors that could be placed at the wound-dressing interface and potentially monitor bacterial growth in real time.Impedance was measured using disposable silver-silver chloride electrodes.The main findings were that the impedance profiles obtained by silver-silver chloride sensors in bacterial suspensions could detect the presence of high cell densities.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, University of Strathclyde, Wolfson Centre, Glasgow, G4 0NW, UK. malcolm.farrow@strath.ac.uk.

ABSTRACT
Infection control is a key aspect of wound management strategies. Infection results in chemical imbalances and inflammation in the wound and may lead to prolonged healing times and degradation of the wound surface. Frequent changing of wound dressings may result in damage to healing tissues and an increased risk of infection. This paper presents the first results from a monitoring system that is being developed to detect presence and growth of bacteria in real time. It is based on impedance sensors that could be placed at the wound-dressing interface and potentially monitor bacterial growth in real time. As wounds can produce large volumes of exudate, the initial system reported here was developed to test for the presence of bacteria in suspension. Impedance was measured using disposable silver-silver chloride electrodes. The bacteria Staphylococcus aureus were chosen for the study as a species commonly isolated from wounds. The growth of bacteria was confirmed by plate counting methods and the impedance data were analysed for discernible differences in the impedance profiles to distinguish the absence and/or presence of bacteria. The main findings were that the impedance profiles obtained by silver-silver chloride sensors in bacterial suspensions could detect the presence of high cell densities. However, the presence of the silver-silver chloride electrodes tended to inhibit the growth of bacteria. These results indicate that there is potential to create a real time infection monitor for wounds based upon impedance sensing.

No MeSH data available.


Related in: MedlinePlus