A microbiological evaluation of apalcillin.

The in vitro activity of apalcillin was tested against 350 clinical isolates of Escherichia coli, Enterobacter, Klebsiella, Proteus, Pseudomonas aeruginosa and Streptococcus faecalis. Using a minimal inhibitory concentration of 16 mg/l as the breakpoint, only 19.7% of the strains were resistant to apalcillin. A regression analysis demonstrated that it is possible to test bacteria for sensitivity with a 20 micrograms apalcillin disc. The results on Mueller-Hinton agar are very similar to those on Iso-Sensitest medium. Like other ureido penicillins, apalcillin is sensitive to most beta-lactamases; it is effective against ampicillin-resistant strains since it penetrates the outer membrane of gram-negative bacteria well and is highly effective against target proteins. Strains producing high amounts of beta-lactamases do become resistant to apalcillin.