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ANTIBACTERIAL ACTIVITY OF SOME DERIVATIVES OF 7‐AMINOCEPHALOSPORANIC ACID AGAINST STAPHYLOCOCCUS AUREUS AND SYNERGISM BETWEEN THESE AND OTHER ANTIBIOTICS
Author(s) -
JAGO MARGARET
Publication year - 1964
Publication title -
british journal of pharmacology and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0366-0826
DOI - 10.1111/j.1476-5381.1964.tb01540.x
Subject(s) - staphylococcus aureus , benzylpenicillin , cephalosporin , fusidic acid , antibiotics , chemistry , microbiology and biotechnology , strain (injury) , staphylococcus , penicillin , bacteria , biochemistry , biology , genetics , anatomy
The N ‐phenylacetyl derivative of 7‐aminocephalosporanic acid (cephaloram) had roughly the same activity as benzylpenicillin against a number of Gram‐positive organisms and about one‐eighth of the activity of benzylpenicillin against penicillin‐sensitive strains of Staphylococcus aureus . This derivative and the N ‐α‐phenoxy‐propionyl derivative of 7‐aminocephalosporanic acid were 4 to 8 and 4 to 16 times as active as methicillin against penicillinase‐ and nonpenicillinase‐producing staphylococcal strains, respectively. Neither the presence of horse serum nor changes in inoculum size appreciably affected the activities of any of the derivatives of 7‐aminocephalosporanic acid which were tested. After forty‐eight subcultures in the presence of antibiotic the increase in minimum inhibitory concentration against the staphylococcus was about four‐times as great for cephaloram as for cephalosporin C. The resistant penicillinase‐producing strains remained stable after six subcultures in antibiotic‐free medium, and all the strains retained coagulase activity. Some degree of cross‐resistance was found between the derivatives of 7‐aminocephalosporanic acid and those of 6‐aminopenicillanic acid. Synergism was observed in vitro between certain derivatives of 7‐aminocephalosporanic acid and 6‐aminopenicillanic acid when they were tested together or with fusidic acid or cephalosporin P 1 against a weak penicillinase‐producing strain of Staphylococcus aureus . Cephalosporin C and cephalosporin C (pyridine), each in combination with benzylpenicillin, showed a significant degree of synergism in protection experiments in mice infected with a strong penicillinase‐producing strain of Staphylococcus aureus .