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Abstract

Cefotaxime has remarkable potency against all Enterobacteriaceae, including Enterobacter species, Citrobacter freundii, Serratia marcescens, and Morganella morganii, Proteus vulgaris, and Providencia species — all of which are resistant to earlier cephalosporins. Cefotaxime generally inhibits >90010 of enteric bacilli at concentrations of ⩽0.5 µg/ml; in one study it inhibited >98% of isolates at ⩽8 µg/ml. For staphylococci and nonenterococcal streptococci, the mean values for the minimal inhibitory concentration50 (MIC50) of cefotaxime (i.e., the lowest concentration inhibiting growth of 50% of tested strains) are 1.1–1.9 µg/ml and 0.01–0.05 µg/ml, respectively. Cefotaxime is inactive against Streptococcus faecalis and most other serogroup D streptococci. It is moderately active against Pseudomonas aeruginosa (MIC50, 19 µg/ml) and Acinetobacter calcoaceticus subspecies anitratus (MIC50, 18 µg/ml). Because the activity of cefotaxime against other pseudomonads and nonfermentative gram-negative bacilli varies, in vitro susceptibility testing must be used as a guide to therapy. Cefotaxime is potent against Haemophilus influenzae and Neisseria species. Infections due to β-lactamase-producing gonococci have been treated effectively with cefotaxime (MIC, mode = ⩽0.OO4 µg/ml). Most anaerobes are highly susceptible to cefotaxime, but the minimal inhibitory concentrations for 10%–20% of Bacteroides fragilis strains (MIC50, 5.3 µg/ml) and other Bacteroides species may exceed obtainable serum concentrations.

The potent antimicrobial activity of cefotaxime appears to be the result of a combination of characteristics which include: β-lactamase stability (types I, III, IV, and V), good ability to pass through the cell membrane, strong affinity for lethal penicillinbinding proteins l a, lb(s), and 3, minimal limitation by the inoculum effect, and bactericidal action at or close to the inhibitory concentration. Clinically useful methods of susceptibility testing have been developed and can be recommended for clinical laboratory use.

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© 1982 by The University of Chicago
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Session I: Basic Science
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