Due to the increasing prevalence of multi-drug resistant (MDR) bacteria, it is now important to begin the search for novel means of defending against such resistant infections. Enterobacteriaceae is a clinically relevant family of bacteria that has shown extensive resistance to many antibiotics, especially after biofilm formation. Inhibitory poly-microbial interactions within this family have been observed. It is known that Citrobacter freundii (CF) growth is significantly inhibited by Klebsiella pneumoniae (KP) through a secreted protein. In this study, the potential KP bacteriocin was screened for its inhibitory effects on CF at various phases of biofilm development. The suspected KP bacteriocin was also tested for its ability to decrease the dosage of antibiotics necessary to inhibit CF growth. Using spectrophotometric analysis, it was shown that the combined treatment of streptomycin and the KP protein allowed a decrease in the minimum inhibitory concentration of streptomycin needed from 50 μM to 32 μM. The combined treatment also yielded increased inhibition at the initial attachment phase of CF infection, as well as after biofilm development. The study uses the secreted KP protein to show the use of poly-microbial interactions within clinical applications. Future projects concerning this KP molecule can pursue the use of a C. elegans model to determine its efficacy in vitro
