Urinary tract infections (UTIs) are among the most common causes of sepsis presenting to 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 almost universal good progress, and 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 that can lead to treatment failure, repeat infections, or significant morbidity and mortality with a poor outcome. It is vitally important to determine if the presenting episode is the result of 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 infections which carry a higher risl of treatment failure as these typically require longer antibiotic courses and sometimes additional workup.
In a clinical context that is not associated with treatment failure or poor outcomes, a simple UTI, or simple cystitis, is an infection of the urinary tract that occurs due to appropriate susceptible bacteria. Typically this is an infection in a nonpregnant immune competent female patient. Pyuria and/or bacteriuria without any symptoms is not a UTI and may not require treatment. An example would be a patient with a Foley catheter or an incidental positive urine culture in an asymptomatic non pregnant immune competent female.
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 right context can be considered as simple UTI, provided there is a prompt response to first-line antibiotics without any long-term sequela.
Any urinary tract infection that does not conform to the above description or clinical trajectory is considered a complicated UTI. In these scenarios, one can 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.
Examples of a complicated UTI include:
Infections occurring despite the presence of anatomical protective measures (UTI in males are by definition considered complicated UTI)
Infections occurring due to anatomical abnormalities, for example, an obstruction, hydronephrosis, renal tract calculi, or colovesical fistula
Infections occurring due to an immune compromised state, for example, steroid use, post chemotherapy, diabetes, elderly population, HIV)
Atypical organisms causing UTI
Recurrent infections despite adequate treatment (multi-drug resistant organisms)
Infections are occurring in pregnancy (including asymptomatic bacteriuria)
Infections are occurring after instrumentation, nephrostomy tubes, ureteric stents, suprapubic tubes or Foley catheters
Infections in renal transplant patients
Infections are occurring in patients with impaired renal function
Infections following prostatectomies or radiotherapy
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