SOME BIOLOGICAL PROPERTIES OF CEPHALOSPORIN C AND A DERIVATIVE

Abstract

Some biological properties of cephalosporin C and of a pyridinium derivative, “cephalosporin CA (pyridine),” were examined. Staphylococci, both penicillinase‐producing and non‐penicillinase‐producing, and some other bacteria tested, were inhibited by 60 to 125 μg cephalosporin C/ml., and 5 to 20 μg cephalosporin CA (pyridine)/ml. The ratio of the activity of the two antibiotics varied for different organisms. Resistance developed slowly on repeated subculture of penicillinase‐producing staphylococci in presence of either antibiotic. The minimum inhibitory concentration of cephalosporin CA (pyridine) upon penicillinase‐producing staphylococci increased 4 to 8‐fold with a 500‐fold increase in inoculum size; with cephalosporin C there was a 2‐fold increase. Their activity was not reduced by serum. Both substances were non‐toxic. They were excreted quantitatively in the urine when given intravenously or subcutaneously to mice. After oral administration less than 5% of the dose was excreted. Cephalosporin CA (pyridine) was about 8 times more active than cephalosporin C in protecting mice from an experimental streptococcal infection, nine doses of 6.25 mg/kg affording complete protection. 1961 British Pharmacological Society