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. 1977 Jan;11(1):88–91. doi: 10.1128/aac.11.1.88

Comparative In Vitro Activity of Nafcillin, Oxacillin, and Methicillin in Combination with Gentamicin and Tobramycin Against Enterococci

Chatrchai Watanakunakorn 1, Cheryl Glotzbecker 1
PMCID: PMC351923  PMID: 836017

Abstract

The in vitro activity of nafcillin, oxacillin, and methicillin alone and in combination with gentamicin and tobramycin against 30 strains of enterococci was investigated. The penicillinase-resistant penicillins were less active than penicillin and ampicillin against the enterococci. Nafcillin was more active than oxacillin and methicillin. Sixty-six percent of strains were inhibited by nafcillin at 6.25 μg/ml, but none was inhibited by oxacillin and methicillin at the same concentration. At 12.5 μg/ml, 83, 16, and 0% were inhibited by nafcillin, oxacillin, and methicillin, respectively. By using a variety of criteria and analyses, it was shown that none of the antibiotic combinations studied demonstrated enhanced killing of all strains of enterococci. Nafcillin-gentamicin was the best combination, and enhanced killing was demonstrated against most strains. Oxacillin was more effective than methicillin when combined with gentamicin. Tobramycin was probably less effective than gentamicin in combination with the penicillinase-resistant penicillins against enterococci.

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Selected References

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

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