Antibacterial Activity of Eight Cephalosporins (Cefamandole Included) on Two Common Respiratory Pathogens (Haemophilus Influenzae and Diplococcus Pneumoniae)

Abstract

Two hundred recent clinical isolates of Haemophilus and Pneumococcus were tested in vitro against eight cephalosporins by means of disc diffusion and agar dilution tests.

Cefamandole was the most active cephalosporin against Haemophilus, 97% of the strains being inhibited by 0,78 mcg per ml of this drug. In order of decreasing bacteriostatic effectiveness, the other drugs were classified as follows: cephapirin, cephalothin, cefoxitin, cephaloridine, cefazolin, cephradine and cephalexin. This, study suggest that prediction of the susceptibility of Haemophilus strains to cephalosporins, on the basis of one drug of this group testing alone, is likely to be hazardous.

The most active cephalosporins against D. pneumoniae were cephaloridine, cephapirine, cefazolin, cefamandole and cephalothin which inhibited 90% of the strains at 0,19 mcg per ml. Cefoxitin, cephradine and cephalexin were clearly less active, requiring 3,12mcg per ml to exhibit the same antibacterial activity. Nevertheless, none of the strains were clearly resistant to these drugs.