The
in vitro activity of Bay K-4999, 6[D-2-(3-furfurylidenamino-2-oxo-imidazolidine-1-carboxamido)-2-(4-hydroxy-phenyl) acetamido] penicillinate, a new ureido penicillin was evaluated against 555 clinical isolates and compared to selected β-lactams. Bay K-4999 inhibited most streptococci at concentrations less than I μg/ml, but was not active against β-lactamase producing
Staphylococcus aureus. The activity of Bay K-4999 against streptococci including
Streptococcus faecalis was similar to the activity of ampicillin. β-Lactamase-producing
Haemophilus influenzae and
Neisseria gonorrhoeae were inhibited by Bay K-4999; albeit at levels higher than needed for non-β-lactamasep roducing isolates. The activity of Bay K-4999 against the members of the Enterobacteriaceae varied from family to family and seemed to correlate with the presence of β-lactamases. Bay K-4999 was more active than ampicillin, piperacillin or mezlocillin against
Escherichia coli lacking β-lactamases. It was more active against Klebsiella than piperacillin or mezlocillin, but cefazolin-resistant strains were not inhibited. It had activity against
Pseudotonas aeruginosa comparable to piperacillin but was less active against
Bacteroides fragilis. Bay K-4999 was hydrolyzed by β-lactamases of
S. aureus, and by both plasmid and chromosomally-mediated β-lactamases of Enterobacteriaceae at rates comparable to ampicillin. It acted synergistically with gentamicin to inhibit resistant
Pseudomonas isolates.
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