Abstract
Disodium α-sulfobenzylpenicillin (sulfocillin) shows a potent in vitro antibacterial activity against Gram-positive and Gram-negative bacteria. In vitro studies of sulfocillin were carried out using the microorganisms lately isolated from clinical source. Sulfocillin demonstrates antibacterial activity against penicillin G resistant strains of staphylococci as nearly strong as that against the sensitive ones. Against Escherichia coli, Proteus vulgaris and P. mirabilis, sulfocillin is also active, while being moderate against P. morgani and Pseudomonas aeruginosa. The antibacterial activity is somewhat influenced by the inoculum size, being strong in the case of a small inoculum at acidic pH. The activity is influenced neither by the presence of horse serum in the medium, nor by the difference of test media. Protein binding rate of the penicillin examined by cellophane bag dialysis is low. Sulfocillin is relativelystable against staphylococcal penicillinase. Bacterial resistance to sulfocillin is demonstrated stepwise by the serial transfer, as in the case of carbenicillin. Cross resistance is found between sulfocillin and other penicillins against Staphylococcus aureus FDA 209P and Escherichia coli NIHJ JC-1, which are made resistant to penicillins by serial subcultures in culture medium. Bactericidal and bacteriolytic examinations with S. aureus FDA 2O9P and E. coli NIHJ JC-1 reveals strong activities of sulfocillin. The paradoxical reduction of both activities at high concentrations of sulfocillin and carbenicillin was observed with S. aureus FDA 209P. Sulfocillin is relatively stable at pH 2.
