Most cases cause by ascending infections from urethra to bladder into the bladder. Female urethra is short and colonized by normal bacteria of the vagina.

Occasional infection may arise from hematogenous spread or lymphatic

Most common organisms 80-90% E.coli (O, K, H antigen serotypes)

  • 10-20% organisms staphylococcus saprophyticus, Proteus, Pseudomonas, Klebsiella and Enterobacter species. Gram positive group b strep and fungal organisms are isolated from indwelling.

Risk factors:

  • School age children congenital abnormalities
  • Postmenstrual due to hypoestrogenic state and vaginal epithelium atrophy, poor hygiene
  • Premenopausal- history UTI, frequent sexual intercourse, diaphragm contraceptionspermicde, increasing parity, DM, obesity, SCT, urinary calculi, neurological conditions

Symptoms frequency and urgency, some suprapubic pain

Acute pyelonephritis combination associated fever and chills

Laboratory traditionally- 100,000 single isolte bacteria was used to define UTI. By diagnosing bacteria with colony count 1,000-10,000 in symptomatic patients improve the sensitivity without significant compromising specificity.

  • Urine dipstick testing for leukocyte esterase or nitrate is rapid and an inexpensive method with sensitivity 75% and specificity 82%


Increase resistance to amoxicillin and trimethoprim-sulfamethoxazole as high as 30% in some populations.


  • Uncomplicated UTI (bactrim PCN not first line rx)
  • 3 day therapy with eradication of 90%
  • Trimethoprim-sulfamethoxazole- (one tablet) 160 mg/800 mg twice daily for 3 days
  • Ciprofloxacin 250 mg- twice daily for 3 days
  • Levofloxacin 250 mg- once daily for 3 days
  • Nitrofurantoin macrocrystals- 50-100 QID for 7 days
  • Nitrofurantoin monohydrate- 100 mg twice daily for 7 days
  • Acute pyelonephritis
  • Outpatient management if patient is reliable. Urine culture performed and empirical therapy started. Regardless rx 14 day oral or parental abx
  • 1st line with flouroquinolone, if area of low resistance trimethoprim sulfamethoxazole
  • Only gm + B lactam- rx amoxicillin, ampicillin and cephalosporin
  • Recurrent urinary tract infection
  • Occur 25-50% within 1 year, treatment with once daily Rx with nitrofurantoin, cipro, sulfa and can be continued for 6-12 months
  • Non medical
  • Increased hydration worsens retention and decreases pH
  • Post coital voiding not effective
  • Drinking cranberry juice decreases symptoms of UTI, because of proanthocyandin inhibits attaching to urinary pathogens
  • Estrogen postmenopausal decreases UTI from reoccurring