- Pseudomonas aeruginosa bacteria are common pathogens that are difficult to treat and are therefore critical to diagnose early when involved in infections.
- The commonly used method for confirming a P. aeruginosa infection is cultural inoculation, which takes 2-3 days to yield results.
- 2-Aminoacetophenone (2-AA) is a volatile substance produced by P. aeruginosa bacteria in high concentrations. Detection of 2-AA using mass spectrometry has proven successful, but the expensive equipment and highly trained personnel involved make this method impractical in the clinic.
- We determined through experiments and in silico docking analysis that there is a binding site between 2-AA and a native LuxR receptor from Vibrio fischeri. Based on this knowledge, we set out to create a biosensor using E. coli harbouring a plasmid encoding LuxR and a reporter luciferase for bioluminescence.
- Through mutagenesis we found a LuxR variant with three amino acids mutated (termed m22). It shows improved binding with 2-AA, yielding a higher specificity (preventing false positives) and a lower detection limit.
- We have designed a prototype device for detecting P. aeruginosa in pus samples using this novel biosensor. It is made of three primary components: a simple plastic tube containing the sample, a cap containing the E. coli-based biosensor, and a bioluminescence detector above the cap. These components are enclosed in a light-sealed aluminium capsule.
- Our device allows inexpensive detection of P. aeruginosa infection in a matter of hours.
- Initial tests with pus from otitis externa (outer ear infections) yielded correct diagnosis in 25/26 cases (7 positive, 17 negative). Only one false negative was reported, which can likely be attributed either to contamination (in the culture used for comparison) or to a rare P. aeruginosa variant that produces less 2-AA.
- Other infections of head and neck origin were correctly detected in 16/20 cases (4 positive, 12 negative) with 4 false negatives. Due to this poorer performance we plan to focus primarily on otitis externa in the short term.
P. aeruginosa, Rapid Diagnostics, Biosensors, Ear Infection, Hospital-Acquired Infection
- Seeking funding for research to improve efficiency and expand to other applications
- Seeking industrial collaboration to advance to clinical trials
- Between 1 million and 3 million cases of otitis externa in the US annually, 20%-60% of which are caused by P. aeruginosa
- At least 90% of malignant otitis externa cases, common in diabetic and immunocompromised individuals, are caused by P. aeruginosa
- Potential applications in cystic fibrosis, otitis media, infected burns, infected catheters, diabetes complications and more
Yael Helman, PI, HU
Noam Sobel, Full Professor and Head of Neurobiology Department, WIS
Ronen Kreizman , Licensing Officer,