Authors: Rainey Hughes, Avalon Marker, Elizabeth Bouwhuis, Yeshaswini Dudde, Bryan Dopp, Scot Carington, Jared Nelson
Mentors: Daniel Clark
Insitution: Weber State University
Antibiotic resistance is a pressing concern within the medical community as bacteria's resistance to antibiotics is escalating alongside the increased usage of antibiotics. According to the CDC, there are close to 2.8 million antibiotic resistant infections every year, with about 35,000 of them resulting in death. This issue has prompted antibiotic stewardship programs in clinics and hospitals to avoid adding to the list of resistant bacteria. Staphylococcus aureus, including the formidable methicillin-resistant S. aureus (MRSA) strain, poses a grave threat due to its antibiotic resistance. The challenges stemming from this resistance become even more formidable when these infecting bacteria assemble into biofilms. Biofilms are robust, adhesive layers composed of bacteria and their extracellular matrices of polysaccharides, proteins, and DNA. In clinical environments like hospitals, biofilms frequently develop on medical devices such as stents, catheters, and IV lines, as well as on metal and plastic surfaces of medical equipment. These biofilms exacerbate antibiotic treatments due to incomplete eradication; the most resilient bacteria persist after exposure.
There is evidence indicating that bacteriophages, which are viruses that will a target particular species or strain of bacteria, have the ability to encode depolymerases. These depolymerases can identify biofilms, adhere to them, and subsequently break down extracellular polymeric substances. Furthermore, bacteriophages can produce lysins, which induce bacterial cell death through cellular lysis. These characteristics can potentially render the bacteria more susceptible to antibiotics. The use of bacteriophages can also be beneficial when it comes to the concern of opportunistic infections. Due to its selectivity to specific bacteria, it can attack the target hosts and leave the natural flora intact.
In our research, we have induced biofilms in our bioreactor. With these biofilms we have been able to test different concentrations of multiple antibiotics, including Vancomycin, Oxacillin, and Carbenicillin in combination with phage K at different concentrations. Our research is aimed at showing a synergistic relationship between phage K and antibiotics, that will allow a subinhibitory concentration of both, in combination, to induce a complete kill and clearance. We have measured this by evaluating bacterial growth via absorbance measurements at 600nm in a Tecan plate reader. We have also measured biofilm clearance using the plate reader and measuring fluorescence at 630nm with a biofilm tablet assay. It was found that a subinhibitory concentration of antibiotic alone did not induce a complete kill and clearing, and that a subinhibitory concentration of phage alone did not induce a complete kill and clearing. However, once these concentrations were used in combination with each other, the complete clearing and killing of MRSA was achieved, and furthermore, was achieved with the antibiotic that the staphylococcus aureus is resistant to. Leading us to believe that we have found a renewed use for a currently ineffective defense mechanism.