Katsuhiko Sawatari

New β‐Lactamase‐Resistant Cephem Treatment of Guinea Pigs Infected with Legionella pneumophila

The in vivo antimicrobial effect of seven new β‐lactamase‐resistant cephems (cefotaxime, latamoxef, ceftazidime, ceftriaxone, cefotiam, cefbuperazone, and MT‐141) on Legionella pneumophila (strain 81–066, serogroup IV) in guinea pigs was compared with that of erythromycin. As the minimal LD100 within one week was about 4.0 × 109 CFU/ml by intraperitoneal injection of the strain, the animals were inoculated with 2.0 ml of twofold dilutions of a suspension of this bacterium. The animals developed purulent peritonitis and systemic involvement demonstrated by the development of periangitis, pneumonia and pleuritis in the lungs. Three different doses of antibiotics were administered intraperitoneally immediately after the rectal temperature reached more than 40 C. Erythromycin had a significant therapeutic effect but none of the new cephems tested death of the infected guinea pigs.