Enterobacter Infection

Eligible subjects will be those age 18 years or more with mono-microbial blood stream infection caused by E. coli, Klebsiella species, Enterobacter species, Serratia species, Citrobacter species, or Proteus species, who have achieved adequate source control, are afebrile and hemodynamically stable for 48 hours or more and have received microbiologically active intravenous therapy for 3-5 days. The bloodstream isolate must be susceptible to amoxicillin, amoxicillin-clavulanate, fluoroquinolones, oral cephalosporins and/or trimethoprim-sulfamethoxazole and the subject must be able to take oral medication directly or through a feeding tube. Exclusions criteria include allergy to all in-vitro active antimicrobials which are available in oral formulations, pregnancy, infective endocarditis, central nervous system infection, terminal illness with expected survival less than 14 days, absolute neutrophil count less than 1,000/ml and hematopoietic or solid organ transplantation within the preceding 90 days. Randomization will be stratified by urinary versus non-urinary source of bacteremia. The primary outcome is treatment failure at 90-days with 10% margin for non-inferiority in the 95% confidence interval around the difference in outcome between the two study groups.