Cefdaloxime pentexil tosilate

This comparative study determined the effect of blood on the antienterococcal activities of the newer cephalosporins. Standardized disk diffusion susceptibility tests were performed with 57 strains of enterococci (30 Enterococcus faecalis strains) on Mueller-Hinton agar with and without 5% sheep blood supplementation. Twelve cephalosporins representing five different structural groups (based on the 7-alpha position substitution) were tested. The greatest frequency of activity enhancement by blood was observed with cefdaloxime and cefdinir (7-alpha hydroxyimino group) against E. faecalis. Cephalosporins with a 7-alpha methoxyimino group (cefpodoxime, cefepime, and cefpirome) had marked increases in zone diameters (3 to > 9 mm) when tested with the blood supplement. Cephems with 7-alpha amino or carboxy substitutions did not demonstrate any enhanced activity. Awareness of this phenomenon is important for the interpretation and accuracy of cephalosporin susceptibility testing.

The disk diffusion zones and the MICs of six newer antimicrobials with significant activity against Haemophilus influenzae were compared using the Haemophilus test medium (HTM) and National Committee for Clinical Laboratory Standards methods. The rank order of potency was cefpodoxime (MIC50, < or = 0.03 micrograms/ml) > cefetamet > cefdinir > cefdaloxime = trospectomycin > cefmetazole (MIC50, 2 micrograms/ml). Susceptible breakpoint interpretive criteria for HTM tests were established that conformed to prior recommendations for each drug when tested against other species. Absolute agreement between methods ranged from 89% to 100% with < or = 1% false-susceptible interpretive errors. The recommended, tentative disk diffusion susceptible interpretive criteria were for 5-micrograms cefdinir disks > or = 20 mm (MIC correlate, < or = 1 micrograms/ml); for 10-micrograms cefetamet disks > or = 18 mm (MIC correlate, < or = 4 micrograms/ml); for 30-micrograms cefetamet disks > or = 21 mm (MIC correlate, < or = 4 micrograms/ml); for 30-micrograms cefmetazole disks > or = 16 mm (MIC correlate, < or = 16 micrograms/ml); for 10-micrograms cefpodoxime disks > or = 21 mm (MIC correlate, < or = 2 micrograms/ml); for 30-micrograms cefdaloxime disks > or = 23 mm (MIC correlate, < or = 2 micrograms/ml) and for 30-micrograms trospectomycin disks > or = 17 mm (MIC correlate, < or = 16 micrograms/ml). beta-Lactamase-negative, ampicillin-resistant (BLNAR) H. influenzae isolates consistently had the highest MICs for each cephalosporin tested.(ABSTRACT TRUNCATED AT 250 WORDS)