The purpose of the study is to compare the safety and effectiveness of the antibiotic levofloxacin by administering a higher dose of levofloxacin and using a shorter course of therapy.

This study will be a pilot study of the efficacy of 750 mg of levofloxacin once daily for 5 days in the treatment of complicated urinary tract infection.

The specific objectives include:

1. To describe clinical and microbiological outcome at short and long term follow-up with 5 days levofloxacin in subjects with acute symptomatic complicated urinary infection, both with and without indwelling catheters.
2. To determine the tolerability of levofloxacin 750-mg once daily in patients with complicated urinary infection.
3. To describe some characteristics of the resolution of the inflammatory response with treatment of complicated urinary infection as demonstrated by changes in urine proteins.
4. To identify any emergence of resistant organisms in recurrent urinary infection following therapy.

Inclusion Criteria:

1. Acute symptoms of urinary infection of less than 7 days duration and an underlying structural or functional abnormality of the genitourinary tract.
2. Pre-therapy urine culture > 105 cfu/ml (> 108 cfu/L) of at least one urinary pathogen.
3. Age 18-80 years, male or female.

Exclusion Criteria:

1. Prior allergic reaction to any fluoroquinolone antimicrobial.
2. Known infection with a fluoroquinolone - resistant organism.
3. Requiring parenteral therapy because of severity of illness or unable to take oral medications.
4. Women who are pregnant or breastfeeding.
5. Requiring additional antimicrobial therapy for infections elsewhere.