In vitro susceptibility and molecular analysis of gentamicin-resistant enterococci.
Enterococci with gentamicin MICs of 256 to 1,024 micrograms/mL were evaluated for susceptibility to ampicillin plus gentamicin synergism. Sixteen of eighteen enterococcal isolates were not susceptible to synergistic killing by ampicillin plus gentamicin; 11 possessed aac(6')-aph(2"), and 4 possessed aph(2")-Ic. A gentamicin MIC of 512 or 1,024 micrograms/mL predicted lack of ampicillin/gentamicin synergism, but a gentamicin MIC of 256 micrograms/mL did not. For six enterococcal strains possessing the gentamicin-resistance gene aph(2")-Ic, ampicillin plus dibekacin, ampicillin plus netilmicin, and ampicillin plus amikacin produced synergistic killing in five, three, and two strains, respectively.
Chow
J W
JW
Research and Medical Service, Department of Veteran's Affairs Medical Center, Detroit, Michigan, USA.
Donabedian
S M
SM
Clewell
D B
DB
Sahm
D F
DF
Zervos
M J
MJ
D000583:Amikacin / Q000494:pharmacology / Q000627:therapeutic use; D000667:Ampicillin / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D017931:DNA Primers / Q000737:chemistry; D015342:DNA Probes / Q000737:chemistry; D004262:DNA Restriction Enzymes; D003982:Dibekacin / Q000494:pharmacology / Q000627:therapeutic use; D004352:Drug Resistance, Microbial / Q000235:genetics; D004357:Drug Synergism; D004587:Electrophoresis, Agar Gel; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics; D005839:Gentamicins / Q000494:pharmacology* / Q000627:therapeutic use; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009428:Netilmicin / Q000494:pharmacology / Q000627:therapeutic use; D010406:Penicillins / Q000494:pharmacology* / Q000627:therapeutic use; D016133:Polymerase Chain Reaction
D017931:DNA Primers; D015342:DNA Probes; D005839:Gentamicins; D010406:Penicillins; D003982:Dibekacin; D009428:Netilmicin; D000667:Ampicillin; D000583:Amikacin; D004262:DNA Restriction Enzymes