Since the isolation of a strain of Cephalosporium acremonium by Brotzu in 1945,1 the recovery of seven natural antibiotic substances from this fungus has been reported.2 One of these antibiotic substances is cephalosporanic acid.3 This nucleus is chemically closely related to the penicillin nucleus, 6-aminopenicillanic acid, differing by having a fused dihydrothiazine B lactam ring, rather than a fused thiazolidine B lactam ring.4 Synthetic manipulation of the 7-aminocephalosporin nucleus by Chauvette et al5 has resulted in the development of cephalothin (Keflin), now available commercially in the United States.
A second important derivative, cephaloridine, chemically 7-[α-(2-Thienyl) acetamido]-3-(1-pyridylmethyl)-3-cephem-4-carboxylic acid betaine, has been produced in England and has been the subject of several favorable clinical reports from that country.6,7
Cephaloridine has essentially the same spectrum of antimicrobial activity as cephalothin, but is more potent against gram-positive organisms. Generally, the pharmacological properties of the two drugs are similar.
Lucas JB, Thayer JD, Utley PM, Billings TE, Hackney JE. Treatment of Gonorrhea in Males With Cephaloridine. JAMA. 1966;195(11):919–921. doi:10.1001/jama.1966.03100110087023