Label-free electrical sensing of bacteria in eye wash samples: A step towards point-of-care detection of pathogens in patients with infectious keratitis

Abstract

The diagnosis of keratitis is based on visual exam, tissue cytology, and standard microbial culturing to determine the type of the infectious pathogen. To prescribe appropriate therapy, it is important to distinguish between bacterial, fungal, and viral keratitis, as the treatments are quite different. Diagnosis of the causative organism has a substantial prognostic importance. Further, timely knowledge of the nature of the pathogen is also critical to adapt therapy in patients unresponsive to empiric treatment options, which occurs in 10% of all cases. Currently, the identification of the nature of the pathogen that causes keratitis is achieved via microbial culture screening, which is laboratory-based, expensive, and time-consuming. The most frequent pathogens that cause the corneal ulcers are P. aeruginosa and S. aureus. Here, we report a microchip for rapid (<1 h) detection of P. aeruginosa (6294), S. aureus (LAC), through on-chip electrical sensing of bacteria lysate. We evaluated the microchip with spiked samples of PBS with bacteria concentration between 101 to 108 CFU/mL. The least diluted bacteria concentration in bacteria-spiked samples with statistically significant impedance change was 10 CFU/ml. We further validated our assay by comparing our microchip results with the standard culture-based methods using eye washes obtained from 13 infected mice.

Label‐Free Quantitative Proteomics Distinguishes General and Site‐Specific Host Responses to Pseudomonas aeruginosa Infection at the Ocular Surface

“…Infected, control, and counter lateral (eye opposite the infection) eyes were collected. We previously demonstrated consistent proliferation of P. aeruginosa at the corneal surface with colony forming units counts and we confirmed the formation of P. aeruginosa biofilms …”

“…Invasive P. aeruginosa clinical isolate 6294 (human keratitis isolate used in animal models) was used for the experiments . The bacterial strain was grown overnight at 37 °C in Tryptic Soy Broth (TSB) (Cardinal Health, Dublin, OH) agar plates supplemented with 5% sheep blood.…”

Development of uracil-DNA-glycosylase-supplemented loop-mediated isothermal amplification coupled with nanogold probe (UDG-LAMP-AuNP) for specific detection of Pseudomonas�aeruginosa

“…Recently, a microchip electrical sensing for detection of P. aeruginosa was developed. The detection limit of spiked eye wash samples at 10 CFU ml −1 was reported ( 33 ). Another study based on magnetic relaxation switch (MRSw) aptasensor for detection of P. aeruginosa with the sensitivity of 50 CFU ml −1 was also reported ( 34 ).…”

Hydrogel Based Sensors for Biomedical Applications: An Updated Review

“…As certain chemicals are taken up by cellular structures for digestion, a kind of chemical-specific biosensor is fashioned [ 26 , 27 ]. Bacteria and fungi microorganisms are categorized in the cell bioreceptor’s group and have been used for toxicity detection [ 28 ]. In the bioreceptors of a cellular structure, abundant carrier proteins that provide facilities to transport a chemical compound from one place to another (surfaces to internal parts or between cells) can be used for molecular recognition [ 29 , 30 , 31 ].…”