Date of Award


Degree Type

Honors College Thesis

Academic Program

Biological Sciences BS


Biological Sciences

First Advisor

Mohamed Elasri, Ph.D.

Advisor Department

Biological Sciences


Staphylococcus epidermidis is a human pathogen that is increasingly known for its role in hospital infections associated with implantable medical devices. Antibiotic resistance has become a concerning issue for these infections as this bacteria have various virulence traits that help to evade immune response and antibiotic treatment. Currently, the most effective way to treat S. epidermidis infection is removal of the implant and long-term antibiotic treatment. S. epidermidis causes infection by expressing several protein factors that induce biofilm formation, the bacteria’s primary virulence mechanism. The purpose of this study was to perform the phenotypic characterizations of the msaABCR operon in S. epidermidis, and we hypothesized that msaABCR may play a role in biofilm formation, protease production, urease production, and deoxyribonuclease production. To test this hypothesis, we constructed a mutant strain by deleting the msaABCR operon from the wild-type strain RP62A. The mutant was later used in several phenotypic assays to observe its activity in biofilm formation, protease production, PIA quantification, and urease production. The msaABCR mutant of RP62A showed increased biofilm relative to RP62A after 24hr incubation. However, the msaABCR mutant showed reduced biofilm compared to RP62A after 48- and 72 hr incubation. Increased protease and urease production was also observed in the msaABCR mutant relative to RP62A. This study provides insights on the role of the msaABCR operon in S. epidermidis virulence mechanisms as it relates to biofilm formation.