Abstract
1. The antibacterial activity of cephapirin (CEP) is strongest against staphylococci. CEP is active against Escherichia coli, Salmonella, Shigella, Klebsiella and some of other Gram-negative bacteria. The activity is almost similar to that of cephalothin (CET), weaker than cephaloridine (CER), and stronger than cephalexin (CEX).
2. The antibacterial activity of CEP against Pseudomonas and Proteus, except P. mirabilis, is very weak as same as CET, CER and CEX, that 97% of the strains tested grew in media with 100 mcg/ml CEP.
3. Cross resistance was observed between CEP and CER or CEX in most strains isolated clinically. Some strains of Klebsiella isolated were sensitive to CEP and resistant to CET.
4. CEP was stable against penicillinase produced by staphylococci, but easily be decomposed by cephalosporinase produced by Gram-negative bacteria.
5. The therapeutic effects of CEP and CET for infections with Staphylococcus and E. coli were almost similar at larger doses, but CEP was superior to CET at small doses.
