The Effects of Combination Antibiotic Therapy on Methicillin-Resistant Staphylococcus aureus

Antibiotics are becoming less effective as bacteria are acquiring resistance, so it is essential that new ones are discovered. An example of a multidrug-resistant bacterial strain is methicillin-resistant Staphylococcus aureus (MRSA), which has infected around 95,000 patients and caused 19,000 deaths per year in the United States alone. Streptomyces are soil bacteria that have been the source of many antibiotics and therapeutics. In order to potentially discover a novel antibiotic to treat resistant bacteria like MRSA, a Streptomyces was isolated from soil and determined to be Streptomyces violaceorectus based on its 16S rRNA gene sequence. S. violaceorectus produces an antibiotic that inhibits the growth of Gram-positive and Gram-negative bacteria. With the recent lack in antibiotic discovery, new treatment options are necessary to combat antibiotic resistance. Combination antibiotic therapy, the simultaneous use of multiple antibiotics, has become a successful clinical treatment, especially with the use of a beta-lactam antibiotic such as ampicillin. This project helped determine the difference in inhibitory effect of the antibiotic produced by S. violaceorectus when used alone and in combination with ampicillin against MRSA. The antibiotic combination was more effective at inhibiting the growth of MRSA, and this difference was significant and replicable over 15 trials. Further analyses will increase our knowledge of the antibiotic produced by S. violaceorectus and its ability to inhibit resistant bacteria by itself or in combination with another antibiotic for future medical use.Molecular Bioscience