This is a first-in-human phase 1 study to assess if ACHN-490 Injection is safe in people. Groups of people will receive either the study medication (ACHN-490) or a placebo (normal saline) as a single infusion. If the single dose is well tolerated then this group will receive 1 dose per day for up to 10 consecutive days. A new group of people will receive the study medication at a higher dose than the previous dose level as long as the previous dose was safe.