Urinary Tract Infection

A urinary tract infection (UTI) is an inflammation of the urinary epithelium usually caused by bacteria from gut flora. A UTI can occur anywhere along the urinary tract including the urethra, bladder, ureter, or kidney. At risk are premature newborns; prepubertal children; sexually active and pregnant women; women treated with antibiotics that disrupt vaginal flora; spermicide users; estrogen- deficient postmenopausal women; individuals with indwelling catheters; and persons with diabetes mellitus, neurogenic bladder, or urinary tract obstruction. Cystitis is more common in women because of the shorter urethra and the closeness of the urethra to the anus (increasing the possibility of bacterial contamination). Up to 50% of women may have a lower UTI at some time in their life.47,48 Uncomplicated UTIs are generally mild and without complications, and they occur in individuals with a normal urinary tract. A complicated (febrile) UTI develops when there is an abnormality in the urinary system or a health problem that compromises host defenses, such as human immunodeficiency virus (HIV), renal transplant, diabetes, or spinal cord injury. UTI may occur alone or in association with pyelonephritis, prostatitis, or kidney stones. Up to 40% of cases of septic shock are caused by urosepsis that present in the emergency room. Recurrent UTI is commonly defined as three or more UTIs within 12 months, or two or more occurrences within 6 months. It may occur as a relapse when there is a second UTI caused by the same pathogen within 2 weeks of the original treatment, or a reinfection that occurs more than 2 weeks after completion of treatment for the same or different pathogen.

Evaluation and Treatment

Infections in symptomatic individuals are diagnosed by urine culture of specific microorganisms with counts of 10,000/mL or more from freshly voided urine. Urine dipstick that is positive for leukocyte esterase or nitrite reductase can be used for the diagnosis of uncomplicated UTI. Risk factors, such as a urinary tract obstruction, should be identified and treated. Evidence of bacteria from urine culture and antibiotic sensitivity warrants treatment with a microorganism-specific antibiotic. Acute uncomplicated cystitis in non-pregnant women can be diagnosed without an office visit or urine culture. If a urine culture and sensitivity are ordered, the urine specimen must be obtained before the initiation of any antibiotic therapy; 3 to 5 days of treatment is most common. Complicated UTI requires 7 to 14 days of treatment. From 20% to 25% of women have relapsing infection within 7 to 10 days requiring prolonged antibiotic treatment. Follow-up urine cultures should be obtained 1 week after initiation of treatment and at monthly intervals for 3 months. Clinical symptoms are frequently relieved, but bacteriuria may still be present. Repeat cultures should be obtained every 3 to 4 months until 1 year after treatment for evaluation and treatment of recurrent infection. Recurrent UTI is effectively treated with short courses of antibiotics, but antibiotic resistance is an emerging problem. Urosepsis and septic shock are medical emergencies that usually demand parenteral, broad-spectrum antibiotic therapy and may require hospitalization. A UTI caused by schistosomiasis is treated with praziquantel. Noninfectious cystitis is associated with radiation or chemotherapy treatment for pelvic and urogenital cancers and is treated symptomatically.

Antibiotics usually are the first line treatment for urinary tract infections. Which drugs are prescribed and for how long depend on your health condition and the type of bacteria found in your urine.

Drugs commonly recommended for UTIs

  • Trimethoprim/sulfamethoxazole (Bactrim, Septra, others)
  • Fosfomycin (Monurol)
  • Nitrofurantoin (Macrodantin, Macrobid)
  • Cephalexin (Keflex)
  • Ceftriaxone

The group of antibiotic medicines known as fluoroquinolones such as ciprofloxacin (Cipro), levofloxacin and others isn't commonly recommended for simple UTIs, as the risks of these medicines generally outweigh the benefits for treating uncomplicated UTIs. In some cases, such as a complicated UTI or kidney infection, your doctor might prescribe a fluoroquinolone medicine if there are no other treatment options. Often, symptoms clear up within a few days of treatment. But you may need to continue antibiotics for a week or more. Take the entire course of antibiotics as prescribed.