Effect of protein binding on the activity of penicillins in combination with gentamicin against enterococci.

Abstract

To assess the effect of protein binding by human serum on the synergistic interaction of penicillins with gentamicin, time-kill curves were determined for four penicillins alone and in combination with gentamicin against 10 blood isolates of enterococci. Killing curves demonstrated synergism with penicillin G plus gentamicin against all 10 strains in either broth or 50% human serum. In broth the combinations of nafcillin plus gentamicin and oxacillin plus gentamicin were synergistic against 10 of 10 strains and 4 of 10 strains, respectively. However, in serum, nafcillin plus gentamicin was synergistically bactericidal against only two strains and oxacillin plus gentamicin against none. Methicillin plus gentamicin was synergistic against none of the enterococci in either medium. Thus, the semisynthetic, penicillinase-resistant penicillins are unlikely to be effective in the therapy of patients with enterococcal endocarditis.

• Authors: R H Glew, R C Moellering Jr
• Journal: Antimicrobial agents and chemotherapy (Antimicrob Agents Chemother) Vol. 15 Issue 1 Pg. 87-92 (Jan 1979) ISSN: 0066-4804 [Print] United States
• PMID: 426508 (Publication Type: Journal Article)

Chemical References

• Gentamicins
• Penicillins

Topics

• Blood Bactericidal Activity
• Drug Synergism
• Endocarditis, Bacterial (drug therapy)
• Enterobacteriaceae (drug effects)
• Gentamicins (pharmacology)
• Humans
• Penicillins (pharmacology)
• Protein Binding
• Streptococcus (drug effects)