Summary
Sulbactam/ampicillin (Unasyn™) possesses the antimicrobial activity of each drug plus the synergistic action and qualities of sulbactam used as a β- lactamase inhibitor. The combination has a spectrum of activity against many Enterobacteriaceae, Haemophilus species, Branhamella catarrhalis, pathogenic Neisseria species, Acinetobacter anitratus, some pseudomonads, nearly all anaerobes (including Bacteroides), Staphylococcus species, streptococci, and the enterococci. Sulbactam/ampicillin was found to be bactericidal, and its minimum inhibitory concentrations (MICs) affected only by high inoculum concentrations (> 106 CFU/ml).
Fixed ratio in vitro susceptibility tests appear to be preferred, since they best approximate clinical formulations and drug pharmacokinetics. The ratio of 1:1 has been studied, but other ratios such as 1:2 (sulbactam/ampicillin) should be evaluated to promote greater test accuracy. Separate interpretive criteria for most Gram- negative bacteria, Haemophilus, and staphylococci appear unnecessary for some tests.
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Jones, R.N. In Vitro Evaluations of Aminopenicillin/β-Lactamase Inhibitor Combinations. Drugs 35 (Suppl 7), 17–26 (1988). https://doi.org/10.2165/00003495-198800357-00005
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DOI: https://doi.org/10.2165/00003495-198800357-00005