This is a Phase 1 open-label study of three doses of amikacin/fosfomycin. Approximately 30 healthy volunteers will be dosed in five cohorts of six subjects each. The first (sentinel) subject in each of the first three cohorts will be dosed alone. If no significant safety or tolerability events occur, the remaining five subjects in each of the first three cohorts will be dosed. The first cohort (n=6) will be administered the 30/12 mg dose of amikacin/fosfomycin. The second cohort (n=6) will be administered the 60/24 mg dose of amikacin/fosfomycin. The third cohort (n=6) will be administered the 90/36 mg dose of amikacin/fosfomycin. All doses in cohorts 1, 2, and 3 will be delivered with the PARI Investigational eFlow Nebulizer System. The fourth cohort (n=6) will be administered the 90/36 mg dose of amikacin/fosfomycin using the PARI LC Sprint Nebulizer. The fifth cohort (n=6) will test the lowest dose level at which all subjects achieved > 0.3 µg/mL amikacin peak serum concentration. The nebulizer used to deliver doses in cohort 5 will be determined after amikacin concentrations from cohorts 1 through 4 are reviewed.