[Investigations on antibacterial activity of apalcillin]

In 201 clinical isolates the antibacterial activity of (2S,5R, 6R)-6-[(R)-2-(4-Hydroxy-1,5-naphthyridine-3-carboxamido) -2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0]heptane-2-carbonic acid (apalcillin, PC-904) a new semisynthetic broad spectrum penicillin, was tested. The activity was almost equal to piperacillin, the at present optimal penicillin derivative, but against pseudomonas apalcillin was clearly superior. Lack of activity as compared to the acylureidopenicillins was found in proteus species whilst its activity against E. coli and klebsiella species was higher. Antagonism was observed in pseudomonas aeruginosa for the combination of apalcillin and cefoxitin which also existed with azlocillin or piperacillin and cefoxitin.