[The influence of a monobactam antibiotic, aztreonam, and other antibiotics on blood coagulation in vitamin K-deficient rats].

The influence of aztreonam (AZT), a new monobactam antibiotic, on blood coagulation was compared with latamoxef (LMOX), cefoperazon (CPZ), cefotetan (CTT) and ampicillin (ABPC). These antibiotics were administered intraperitoneally once a day for 7 days to rats fed a vitamin K-deficient diet. On the 8th day, blood coagulation activity and bacteria in the caecum were observed. 1) One hundred mg/kg and 300 mg/kg of LMOX prolonged the blood coagulation time and decreased normal prothrombin in a dose-dependent manner. CPZ, CTT and ABPC (300 mg/kg each) decreased both of these parameters, but not as much as LMOX did. AZT (300 mg/kg) had no effect on these parameters. 2) Three hundred mg/kg of ABPC and LMOX decreased the viable cell counts of all aerobic G (+), aerobic G (-), and anaerobic bacteria and yeast, while AZT decreased only aerobic G (-) bacteria. These results suggest that AZT may be less likely to induce hypoprothrombinemia than other antibiotics in clinical use.