[6R-[(R)-2-[3-[2-(p-Aminosulfonyl)anilino-4-hydroxy-5- pyrimidinyl]ureido]-2-(4-hydroxyphenyl)acetamido]-penicillanic acid, sodium salt (VX-VC 43), a new broad-spectrum beta-lactam antibiotic. In vitro and in vivo antibiotic activity].

6R-[(R)-2-[3-[2-(p-Aminosulfonyl) anilino-4-hydroxy-5-pyrimidinyl] ureido]-2-(4-hydroxyphenyl)acetamido]-penicillanic acid, sodium salt (VX-VC 43), a pyrimidinylureidopenicillin, is a broad-spectrum antibiotic. In vitro it is more active than piperacillin, apalcillin and mezlocillin especially against the following strains; E. coli, Ps. aeruginosa, Ps. stutzeri, K. pneumoniae, Eb. cloacae, Ser. marcescens, Proteus, Sh. flexneri, Y. enterocolitica, Cb. freundii, Acb. calcoaceticus, Bacteroides and Sc. faecalis. The minimal inhibitory concentration (MIC, micrograms/ml), for VX-VC 43 lies between 0.06 and 4 for piperacillin between 0.25 and 16, for apalcillin between 0.25 and 8, and for mezlocillin between 0.5 and 32. The action of VX-VC 43 is bactericidal. In tests against patient-isolates of E. coli (n = 50), Ps. aeruginosa (n = 50), K. pneumoniae (n = 46) and Eb. cloacae (n = 50) VX-VC 43 is clearly more active than Piperacillin. In the case of Ps. aeruginosa 2 micrograms/ml VX-VC 43 inhibits 43.9% of the bacteria and 8.5% with piperacillin; for E. coli 0.25 micrograms/ml inhibits 43.9% with VX-VC 43 and 0% with piperacillin; for K. pneumoniae 4 micrograms/ml inhibits 43.7% with VX-VC 43 and 28% for piperacillin; with Eb. cloacae 2 micrograms/ml inhibits 78% with VX-VC 43 and 4% with piperacillin. Addition of 50% human serum, or a change in culture medium pH (from 6 to 8) has little or no effect on the MIC of VX-VC 43 or piperacillin.(ABSTRACT TRUNCATED AT 250 WORDS)