A novel mechanism of resistance to penicillin-gentamicin synergism in Streptococcus faecalis.
A patient with enterococcal endocarditis, who relapsed after repeated courses of apparently adequate treatment with ampicillin plus gentamicin, was subsequently cured with ampicillin-tobramycin therapy. The organisms isolated from this patient were strains of Streptococcus faecalis that were resistant to penicillin (or ampicillin)-gentamicin synergism but not to penicillin (or ampicillin)-tobramycin synergism. The mechanism of resistance in these strains appears to be related to a specific defect in the intracellular uptake of gentamicin (but not tobramycin) in the presence of penicillin.
D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004697:Endocarditis, Bacterial / Q000188:drug therapy*; D013293:Enterococcus faecalis / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D005260:Female; D005839:Gentamicins / Q000378:metabolism / Q000627:therapeutic use*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010406:Penicillins / Q000378:metabolism / Q000627:therapeutic use*; D013290:Streptococcal Infections / Q000188:drug therapy*; D014031:Tobramycin / Q000378:metabolism
D005839:Gentamicins; D010406:Penicillins; D014031:Tobramycin