Masters Thesis

Identification of Two Novel Β-lactamases from an Extensively Antibiotic Resistant Strain of Empedobacter Falsenii, Wf282

The spread of antibiotic resistance is rapidly threatening the effectiveness of antibiotics in the clinical setting. More infections are being caused by pathogenic bacteria that have gained resistance to many or all antibiotics that are currently available. Empedobacter falsenii is an emerging nosocomial pathogen. Wf282 is an extensively resistant strain of E. falsenii in which two novel β-lactamases (bla), EBR-2 and EPF-1, have been identified. The objectives of this work were to characterize these two novel genes and describe the potential role of this species as a reservoir of theses resistance determinants. Escherichia coli TOP10 cells harboring a plasmid containing blaEBR-2 showed approximately a two-fold and a four-fold decrease decrease in susceptibility to imipenem and meropenem, respectively, according to the MIC values. Acinetobacter nosocomialis M2 cells harboring a plasmid containing blaEBR-2 showed approximately a four-fold decrease in susceptibility to imipenem and an eight-fold decrease in susceptibility to meropenem. E. coli TOP10 cells harboring a plasmid containing blaEPF-1 showed a two-fold decrease in susceptibility to ceftazidime. The EBR-2 protein showed the highest catalytic efficiency for penicillin G as compared to meropenem and ampicillin and was unable to hydrolyze cefepime. EPF-1 was solubilized using an auto-induction medium but was not well purified. The results described in this work broaden the current understanding of the role of β-lactamases in the Flavobacteriaceae family and suggest that E. falsenii Wf282 may be a reservoir of these novel resistance determinants.

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