Penicillin resistance in Enterococcus faecalis: molecular determinants and epidemiology

Enterococcus faecalis plays a significant role in hospital-acquired infections (HAIs), and combination of penicillin with aminoglycoside is important in therapy of invasive HAIs. Penicillin resistance in this organism is due to modification of the drug target, penicillin-binding protein (PBP5), its overproduction and expression of β-lactamase. Although rare, this phenotype is often associated with multi-resistant high-risk enterococcal clonal complexes (HiRECCs), such as CC2 and CC9 which may promote its spread in the near future.