Student Research

Rapid detection of Methicillin-Resistant Staphylococcus aureus using genetically immobilized fiber optic biosensors

Biosensors are emerging to become the standard in medical diagnostics due to their rapid detection capabilities. Methicillin-resistant Staphylococcus aureus (MRSA) is typically known for skin infections and can be life-threatening if not treated immediately. Its methicillin-resistance, encoded by the mecA gene, protects it from beta-lactam antibiotics. By targeting the mecA gene DNA sequences, MRSA can be detected rapidly compared to other diagnostic techniques that can take up to 48 hours. Our goal is to detect MRSA using fiber optic biosensors that our group demonstrated worked for antibody-antigen interactions in a similar study, where the tapered regions of the sensors were functionalized by immunoglobulin-G (Ig-G) and tested for detection of anti-IgG. Such antibody-antigen reactions created a biological nanolayer modifying the waveguide structure leading to a change in the sensor signal. The limit of detection was estimated to be less than 50 ng/mL with low temperature sensitivity. Utilization of the rate of the sensor peak shift within the first few minutes of antibody-antigen reaction was proposed as a rapid detection method. The reagents used in this study, excluding IgG, are the same needed for the mecA immobilized biosensors. We expect MRSA to be detected when mecA DNA fragments immobilized on a silica surface hybridize with MRSA DNA extracts (prepared using lysostaphin cell lysis and heat-treatment of cells). We anticipate this interaction will modify the refractive index of the medium near the fiber's surface similar to the rapid detection method in the IgG immobilized study.

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