Cyclacillin: A Clinical and in Vitro Profile

The levels of orally administered cyclacillin and ampicillin were determined in serum and urine of 11 healthy male volunteers, and cyclacillin was found to be more rapidly absorbed. Cyclacillin, 2–12 g daily, was administered to 33 patients in the Greater Manila area who had various infections: cellulitis, urinary tract infections, respiratory tract infections, enteric fever, and severe systemic infections. The etiologic organisms were isolated and tested in vitro for sensitivity to cyclacillin and to either benzylpenicillin or ampicillin. The Staphylococcus aureus isolates were generally more susceptible to benzylpenicillin than to cyclacillin, and nearly all the gram-negative bacteria were resistant to this agent. Nevertheless, cyclacillin was fairly effective against infections due to the gram-positive cocci (including penicillin-resistant staphylococci). Urinary tract infections also responded well initially, but superinfections often followed. Only one of five severe infections responded well. The results of the treatment of enteric fever with dosages of 6–12 g were generally poor. Side effects were negligible.