A comparison of antibiotic regimens in the treatment of acute melioidosis in a mouse model

Melioidosis is caused by the Gram-negative bacillus Burkholderia pseudomallei. Most clinical reports of disease are from south-east Asia and northern Australia. The organism is intrinsically resistant to most commonly available antibiotics. Standard therapy includes ceftazidime either alone or in combination with co-trimoxazole. The clinical advantage in adding co-trimoxazole has never been determined; nor has the activity of newer, fourth-generation cephalosporins, such as cefepime, been studied in the treatment of this condition. BALB/c mice have been shown to represent an animal model of melioidosis. This animal model was used in this study to compare the efficacy of ceftazidime and cefepime alone or with co-trimoxazole, in the therapy of melioidosis. Antibiotic levels in the mice were determined by HPLC, and dosing was modified to keep plasma antibiotic levels at or above the MIC for the organism-antibiotic combination for a significant part of a 12 h period. Bacterial load, as determined by splenic counts, showed that ceftazidime in combination with co-trimoxazole was the most effective therapeutic option. The animal model described in this study can be used as a preliminary evaluation of therapeutic options for melioidosis.