Identification of two novel b-lactamases (EBR-2 and EPF-1) from Empedobacter (formerly Wautersiella) falsenii comb.nov.

DIXON C.; CHIEM K.; TRAGLIA G.; BRIGGS N.; ALMUZARA M.; BARBERIS CLAUDIA; MONTAÑA SABRINA; MERINO C.; MUSSI MA; TOLMASKY M; IRIARTE A.; VAY C.; RAMÍREZ M.S.

San Diego

Congreso; Interscience Conference of Antimicrobial Agents and Chemotherapy (ICAAC); 2015

American Society for Microbiology

Background: Due to the dramatic increase in antibioticresistance levels observed all over the world researchrelated to this topic is imperative. This increase has beenobserved as a result of the missuse of antibiotics leading toan increase in infections caused by emerging multi-drugresistant pathogens, such as the one studied here,Empedobacter falsenii. E. falsenii comb. nov. was firstdescribed in 2006 and renamed in 2014. Methods: In theyear 2013, a strain of E. falsenii (Wf282) was isolated. Thestrain was found to be resistant to different antibiotics,including carbapenems and colistin. Whole-genome shotgunsequencing was performed and two putative β-lactamaseswere identified. Recombinant plasmids harboring theβ-lactamases were generated and sequence analysis wasperformed to confirm them. BLAST V2.0 software was usedfor sequence analysis. Disk diffusion tests as well as MICsand synergy tests to various β-lactams and β-lactams inhibitors were done. Results: Sequence analysis of theputative β-lactamases genes showed that one has a 97% ofidentity to a carbapenemase EBR-1 and the other 69% ofidentity with a putative β-lactamase. E. coli transformedwith the recombinant plasmids was used in thesusceptibility tests. Disk diffusion tests and MICs showedthat one of the β-lactamases (EBR-2) possess activityagainst meropenem and imipenem and is inhibited byEDTA. The results obtained for the other novel β-lactamase(EPF-1) showed that it possesses some activity againstceftazidime and cefepime. Moreover a clear inhibition ofEPF-1 was observed using the amoxicillin/clavulanic acid.Conclusions: Two novel β-lactamases, EBR-2 and EPF-1,were identified in this species. The presence of thisenzymes allow us to find novel antibiotics resistance traitsthat may explain the phenotype present in this strain aswell as its potential role as a reservoir of antibioticresistance genes. Further experimentation is needed inorder to fully characterize EBR-2 and EPF-1, identifying thepreferential substrates as well as the kinetic features of theenzymes.