University of Arkansas, Fayetteville


As a serious expense for both the hospital and the patient, nosocomial infections create a burden on the health care industry that is not easily overcome. Among the infections commonly contracted in the hospital environment, those associated with the Clostridium difficile bacterium account for millions of cases each year. Largely due to the nature of C. difficile infection as a response to the disruption of the normal flora of the colon caused by antibiotic activity, no completely effective treatment for this condition has been identified. It is this problem that forms the foundation for research devoted to the development of a control mechanism for the expression of the oligopeptide permease (opp) genes, which are important metabolic structural genes in the C. difficile genome. In the work reported here, a genetic construct with the ability to monitor the activity of the dual promoter known to control the expression of the opp genes was created. When this construct was used in combination with a highly expressed gene for an opp regulatory protein, we found that gene expression associated with the oppDF promoter was enhanced significantly, while oppAB expression was greatly inhibited. This pattern was observed using fructose, glucose, mannitol, and pep tides as growth substrates, with the degree of induction and repression varying with the nature of the substrate. Future applications of the pUA442 construct may make it possible to determine the specific conditions that prevent the formation of structures of metabolism in C. difficile on the most basic transcriptional level, and ultimately allow for the regulation of one of the nosocomial infections that so greatly contributes to the problems of the health care industry.