Urinary Tract Infection
| Overview |
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- Urinary Tract Infections (UTIs) are infections of the urinary tract and includes infections of the urethra, termed urethritis, as well as infections of the bladder, termed cystitis. Infections of the kidneys are considered separately in acute pyelonephritis.
| Etiology |
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- UTIs are typically caused by bacteria and a wide variety of organisms can be the source of infection; however, in general, gram negative bacteria are usually to blame. Because most UTIs originate from urethral seeding, the offending organism is typically part of the normal GI flora. The most common organism is Escherichia coli although the following bacteria can also yield UTIs: Proteus mirabilis, Klebsiella pneumoniae, Enterobacter, Serratia, Pseudomonas aeruginosa. Certain sexually transmitted diseases can also cause UTIs and should be considered in young, sexually-active patients who have recently acquired a new partner. These organisms include: Chlamydia trachomatis, Neisseria gonorrhea, or Ureaplasma urealyticum.
| Pathogenesis |
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- The entire urinary tract and kidneys are in essence a single continuous tube. Therefore, bacteria which have gained access to the urethra (causing urethritis) can extend into the bladder and thus cause cystitis. From the bladder infections can ascend through the ureters and gain access to the kidneys via the renal pelvis and calyces, causing acute pyelonephritis which is discussed separately.
| Clinical Consequences |
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- Overview
- The acute onset of the symptomology described below is a strong indicator of UTI in at-risk populations. Generally, the symptomology of cystitis and urethritis largely overlap. However, the presence of constitutional symptoms and flank pain indicates likely extension of infection into the kidneys and thus the presence of acute pyelonephritis.
- Signs and Symptoms
- Dysuria, urinary frequency and urgency as well as suprapubic pain
- Urinalysis will often show bacteruria, pyuria, and hematuria
- Complications
- Acute Pyelonephritis: Spread of infection into the kidneys
| Risk Factors |
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- Female Gender: UTIs are very common among adult women and fairly rare among men until late in life
- Sexual Activity: Physical trauma during sexual activity substantially increases the risk of UTI from a GI flora source such as E. Coli
- Pregnancy: UTIs are very common in pregnant women and tend to spread much more rapidly
- Urinary Tract Obstruction: Obstructions impede urine flow thus facilitating establishment of infection
- Renal and Urinary Tract Stones: Caliculi impede urine flow, damage the urinary epithelium, and provide a nidus for establishment of infection
- Neurogenic Bladder: Stasis of urine renders the bladder prone to infection
- Diabetes Mellitus: Increased risk is probably due to impaired immunity in these individuals
- Foley Catheter: Urinary catheters provide an excellent nidus upon which infection can establish and route by which it can extend.