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. 1973 Nov;4(5):564–568. doi: 10.1128/aac.4.5.564

Synergism of Carbenicillin and Gentamicin Against Enterococci

Robert D Libke 1, Claude Regamey 1, John T Clarke 1, William M M Kirby 1
PMCID: PMC444596  PMID: 4791492

Abstract

Carbenicillin and gentamicin were tested for synergism against 25 strains of enterococci by two different methods. Killing curves were determined by doing serial colony counts of broth cultures containing the antibiotics separately and in combination. The combination was synergistic for all 25 strains with 75 and 4 μg of carbenicillin and gentamicin per ml, respectively. Reducing the concentrations to 50 and 3 μg of the antibiotics per ml with four strains significantly reduced the rate of killing of the combination. Synergism was also studied by constructing isobolograms, by using the standard two-dimensional broth dilution checker-board technique, and by measuring the end points both for minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs). Synergism was present for all 25 strains when bactericidal end points (MBCs) were evaluated, but was present for only 7 of the 25 strains when MICs were used to construct isobolograms. The time and effort involved were roughly the same for killing curves and for isobolograms, and it was concluded that neither had a distinct advantage over the other.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. BULGER R. J., KIRBY W. M. GENTAMICIN AND AMPICILLIN: SYNERGISM WITH OTHER ANTIBIOTICS. Am J Med Sci. 1963 Dec;246:717–726. doi: 10.1097/00000441-196312000-00013. [DOI] [PubMed] [Google Scholar]
  2. Ericsson H. M., Sherris J. C. Antibiotic sensitivity testing. Report of an international collaborative study. Acta Pathol Microbiol Scand B Microbiol Immunol. 1971;217(Suppl):1+–1+. [PubMed] [Google Scholar]
  3. Jawetz E. Combined antibiotic action: some definitions and correlations between laboratory and clinical results. Antimicrob Agents Chemother (Bethesda) 1967;7:203–209. doi: 10.1128/AAC.7.2.203. [DOI] [PubMed] [Google Scholar]
  4. Klastersky J., Cappel R., Daneau D. Clinical significance of in vitro synergism between antibiotics in gram-negative infections. Antimicrob Agents Chemother. 1972 Dec;2(6):470–475. doi: 10.1128/aac.2.6.470. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Klastersky J., Swings G., Daneau D. Antimicrobial activity of the carbenicillin-gentamicin combination against gram-negative bacilli. Am J Med Sci. 1970 Dec;260(6):373–380. doi: 10.1097/00000441-197012000-00006. [DOI] [PubMed] [Google Scholar]
  6. McCracken G. H., Jr, Nelson J. D., Thomas M. L. Discrepancy between carbenicillin and ampicillin activities against enterococci and Listeria. Antimicrob Agents Chemother. 1973 Mar;3(3):343–349. doi: 10.1128/aac.3.3.343. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Moellering R. C., Jr, Wennersten C., Weinberg A. N. Studies on antibiotic synergism against enterococci. I. Bacteriologic studies. J Lab Clin Med. 1971 May;77(5):821–828. [PubMed] [Google Scholar]
  8. Moellering R. C., Jr, Wennersten C., Weinberg A. N. Synergy of penicillin and gentamicin against Enterococci. J Infect Dis. 1971 Dec;124 (Suppl):S207–S209. doi: 10.1093/infdis/124.supplement_1.s207. [DOI] [PubMed] [Google Scholar]
  9. Moellering R. C., Jr, Wennersten C., Weinstein A. J. Penicillin-tobramycin synergism against enterococci: a comparison with penicillin and gentamicin. Antimicrob Agents Chemother. 1973 Apr;3(4):526–529. doi: 10.1128/aac.3.4.526. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Orfanakis M. G., Wilcox H. G., Smith C. B. In vitro studies of the combined effect of ampicillin and sulfonamides on Nocardia asteroides and results of therapy in four patients. Antimicrob Agents Chemother. 1972 Mar;1(3):215–220. doi: 10.1128/aac.1.3.215. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Preston D. A., Wick W. E. Preclinical assessment of the antibacterial activity of nebramycin factor 6. Antimicrob Agents Chemother (Bethesda) 1970;10:322–327. doi: 10.1128/AAC.10.2.322. [DOI] [PubMed] [Google Scholar]
  12. Sabath L. D. Synergy of antibacterial substances by apparently known mechanisms. Antimicrob Agents Chemother (Bethesda) 1967;7:210–217. [PubMed] [Google Scholar]
  13. Standiford H. C., Kind A. C., Kirby W. M. Laboratory and clinical studies of carbenicillin against gram-negative bacilli. Antimicrob Agents Chemother (Bethesda) 1968;8:286–291. [PubMed] [Google Scholar]
  14. Standiford H. D., De Maine J. B., Kirby W. M. Antibiotic synergism of enterococci. Relation to inhibitory concentrations. Arch Intern Med. 1970 Aug;126(2):255–259. [PubMed] [Google Scholar]
  15. Watanakunakorn C. Penicillin combined with gentamicin or streptomycin: synergism against enterococci. J Infect Dis. 1971 Dec;124(6):581–586. doi: 10.1093/infdis/124.6.581. [DOI] [PubMed] [Google Scholar]
  16. Weinstein A. J., Moellering R. C., Jr Penicillin and gentamicin therapy for enterococcal infections. JAMA. 1973 Feb 26;223(9):1030–1032. [PubMed] [Google Scholar]
  17. Wilkowske C. J., Facklam R. R., Washington J. A., 2nd, Geraci J. E. Antibiotics synergism: enhanced susceptibility of group D streptococci to certain antibiotic combinations. Antimicrob Agents Chemother (Bethesda) 1970;10:195–200. [PubMed] [Google Scholar]
  18. Zimmermann R. A., Moellering R. C., Jr, Weinberg A. N. Mechanism of resistance to antibiotic synergism in enterococci. J Bacteriol. 1971 Mar;105(3):873–879. doi: 10.1128/jb.105.3.873-879.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]

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