Complicated Urinary Tract Infections

Excerpt

Urinary tract infections (UTIs) are among the most common causes of sepsis presenting in hospitals. UTIs have a wide variety of presentations. Some are simple UTIs that can be managed with outpatient antibiotics and carry a reassuring clinical course with an almost universally good outcome. On the other end of the spectrum, florid urosepsis in a comorbid patient can be fatal. UTIs can also be complicated by several risk factors leading to treatment failure, repeat infections, or significant morbidity and mortality with a poor outcome. It is vitally important to determine if the presenting episode results from these risk factors and whether the episode is likely to resolve with first-line antibiotics.

It is important to properly define a complicated UTI as an infection that carries a higher risk of treatment failure. These infections typically require longer courses of treatment, different antibiotics, and sometimes additional workups.

In a clinical context not associated with treatment failure or poor outcomes, a simple UTI (or simple cystitis) is an infection of the urinary tract due to appropriate susceptible bacteria. Typically this is an infection in an afebrile non-pregnant immune-competent female patient. Pyuria and/or bacteriuria without any symptoms is not a UTI and may not require treatment. An example would be an incidental positive urine culture in an asymptomatic, afebrile non-pregnant immune-competent female. A complicated UTI is any UTI other than a simple UTI, as defined above. Therefore, all UTIs in immunocompromised patients, males, pregnant patients, and those associated with fevers, stones, sepsis, urinary obstruction, catheters, or involving the kidneys are considered complicated infections.

The normal female urinary tract has a comparatively short urethra and, therefore, carries an inherent predisposition to proximal seeding of bacteria. This anatomy increases the frequency of infections. Simple cystitis, a one-off episode of ascending pyelonephritis, and occasionally even recurrent cystitis in the proper context can be considered a simple UTI, provided there is a prompt response to first-line antibiotics without any long-term sequela.

Any UTI that does not conform to the above description or clinical trajectory is considered a complicated UTI. In these scenarios, one can almost always find protective factors that failed to prevent infection or risk factors that lead to poor resolution of sepsis, higher morbidity, treatment failures, and reinfection. The reason for the distinction is that complicated UTIs have a broader spectrum of bacteria as an etiology and have a significantly higher risk of clinical complications. The presence of urinary tract stones and catheters is likely to increase the incidence of recurrences compared to patients without these foci of bacterial colonization.

Examples of a complicated UTI include:

1. Infections occurring despite the presence of anatomical protective measures (UTIs in males are, by definition, considered complicated UTIs)

2. Infections occurring due to anatomical abnormalities, for example, an obstruction, hydronephrosis, renal tract calculi, or colovesical fistula

3. Infections occurring due to an immunocompromised state, for example, steroid use, postchemotherapy, diabetes, HIV, older individuals

4. Atypical organisms causing UTI

5. Recurrent infections despite adequate treatment (multi-drug resistant organisms)

6. Infections occurring in pregnancy (including asymptomatic bacteriuria)

7. Infections occurring after instrumentation, such as placing or replacement of nephrostomy tubes, ureteric stents, suprapubic tubes, or Foley catheters

8. Infections in renal transplant and spinal cord injury patients

9. Infections in patients with impaired renal function, dialysis, or anuria

10. Infections following surgical prostatectomies or radiotherapy