Studies were done on the effectiveness and safety of panipenem/betamipron, a new carbapenem antibiotic, in infections in the surgical domain and its safety when dissolved in infusions containing lactate. The obtained results are summarized as follows. The preparation, 0.5 g/0.5 g or 1.0 g/1.0 g, was administered by intravenous drip infusion 2 to 3 times a day to 31 cases of patients with infections in the surgical domain. A physiological saline solution was used as the solvent in 21 cases (group A) of them and Solita T3, an infusion containing lactate, was used as the solvent in the 10 remaining cases (group B). As for its clinical effects, results were rated as "excellent" in 20, "good" in 7, "fair" in 3 and "no response" in 1 out of the 31 cases, and the efficacy rate was 87.1%. Regarding its bacteriological effects, results were rated as "disappeared" in 22, "decreased" in 2, "unchanged" in 1 and "unknown" in 1 out of 26 cases from which bacteria were isolated, hence the bacteria-clearance rate was 88.0%. As for side effects, skin rash was seen in 1 case and slight increases of GOT and GPT were noted as abnormal changes in laboratory data in 2 cases. These side effects were all observed among the cases in group A but not at all in group B where a lactate containing infusion was used as the solvent.