Ampicillin susceptibility can predict in vitro susceptibility of penicillin-resistant, ampicillin-susceptible Enterococcus faecalis Isolates to amoxicillin but not to imipenem and piperacillin

Our findings demonstrated that the results obtained for ampicillin may accurately predict the in vitro susceptibility to amoxicillin but not to imipenem and piperacillin among isolates of Enterococcus faecalis resistant to penicillin but susceptible to ampicillin, which have emerged recently, in contrast to penicillin- and ampicillin-susceptible isolates.