The purpose of this study is to determine if a single dose of amikacin (a type of antibiotic) can be used to effectively treat emergency department patients with uncomplicated cystitis (inflammation of the bladder). Participating in this study will allow the patient to treat their urinary tract infection (UTI) with a single intramuscular (IM (into the arm)) or intravenous (IV (into the vein)) shot of amikacin, rather than having to go to the pharmacy to pick up a prescription for antibiotics, and then take antibiotics for 3-7 days. A single dose of amikacin has been demonstrated to be safe, effective and well tolerated in other studies, but some patients may decline to participate because they do not wish to have an IV or IM shot, or because they don't want to speak on the phone with a research assistant three times over the next 30 days.