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  • Introduction
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Infector Detector: Specifications

The system must be able to detect the presence of biofilms on urinary catheters by detection of AHL, at a minimum concentration of 5nM, and report with a visual signal within 3 hours. It must work within a temperature range of 20°-30°C, be portable and easy to use, have a shelf life of at least seven days, and must not be harmful or infectious.

Property	Value
Inputs	System must be sensitive to AHL concentration between 5-50nM
Outputs	System must give a visual signal if bacteria is present
Operating Conditions	System must operate within temperature 20-30°C
	System must operate within pH range of 6-8
Health Regulations	System Must not be living replicating bacteria
Response Time	System needs to have a response time under 3 hour
Lifespan	System must have a shelf life of 7 days
Packaging	System must be portable and convenient to use

Project Plan

The formation of biofilms in bacteria is a common phenomenon and is present in many opportunistic pathogens. The biofilm is composed of a series of polysaccharides and proteins, which binds together to form a large complex, adhering the bacteria together. The presence of biofilms act as a defensive barrier against the immune system, and also external anti-microbial agents. In order to coordinate the formation of a biofilm, the concentration of bacteria must be relatively large. To do this, many bacteria uses some form of quorum sensing to orchestrate the formation of a biofilm(reference 1).

Many forms of quorum sensing components are used be bacteria. Some systems including the Lux (Las) system, encoded by the lux operon used in Escherichia bacteria. The lux system produces acyl-homoserine lactones (AHL), which is freely diffusible. Also the fsr system found in Enteroccous encodes for a signaling peptide, which is detected by a two component signaling system. Both systems are found to be active during biofilm formation, suggesting that quorum sensing is essential in biofilm formation.

For our project, we have decided to target the Lux system, since it is a better understood. Our device will detect the specific signaling molecule 3-oxohexanoyl-homoserine lactone (3OC₆HSL). This molecule can be detected by the counterpart LuxR.

For future research, it is possible to attempt to use detectors in other quorum sensing systems, such as those found in Enteroccocus. Alternatively, other pathogen-secreted materials can be used to detect biofilms. Examples will include α-toxins found in Staphylococcus.