Melioidosis, an infection caused by the bacterium Burkholderia pseudomallei, is a major cause of community-acquired septicaemia in northeast Thailand. Common manifestations include cavitating pneumonia, hepatic and splenic abscesses, and soft tissue and joint infections. Despite improvements in diagnostic procedures and treatment, the mortality of severe melioidosis remains unacceptably high - approximately 35% with currently used antibiotics (ceftazidime or co-amoxiclav). There is clear evidence that antibiotics can affect mortality; the use of ceftazidime rather than previous regimens (doxycycline + chloramphenicol + co-trimoxazole) led to a 50% reduction in mortality from 80% to 35%. However, the mortality in the first 48 hours has not been altered by any treatment regimen. A key question is whether alternative antibiotics could improve early outcome. The hypothesis tested is that meropenem is superior to ceftazidime in terms of mortality for the treatment of melioidosis.