Urinary Tract Infection
Urinary tract infection (UTI) is a common post-operative complication for various surgical procedures. Patients that develop UTIs in the peri-operative period have higher rates of mortality and longer lengths of stay, so it is important that they are promptly recognised and managed.
There are several factors that increase the risk of developing post-operative urinary tract infection:
- Age > 60yrs
- Significant comorbidities (e.g. renal failure, diabetes mellitus)
- Catheterisation, foreign body (e.g. artificial sphincter), or recent instrumentation
- Urinary retention or renal stones
Common causative organisms are E. Coli, Klebsiella sp., Enterobacteur sp., Proteus sp., Pseudomonas sp., and Staphylococcus sp.
The classical clinical features of UTI are urinary frequency, urgency, dysuria, and pyrexia. On examination, these patients often have mild suprapubic pain and be pyrexial.
A UTI should also be considered in the any patient who presents:
- With delirium
- Septic (without a clear foci of infection)
- In acute urinary retention
It is also important to assess for features of pyelonephritis as well (loin pain, renal angle tenderness, or pyrexia).
A urine dipstick* should be performed initially for all suspected cases (despite a high rate of contamination seen in the elderly population).
*Sterile pyuria is the presence of elevated numbers of white cells in the urine however has appears sterile using standard culture techniques. Causes of sterile pyuria include an inadequately treated UTI, a sexually-transmitted infection, or renal stones
If the urine dipstick is positive (nitrites* or leukocyte esterase ± blood) or clinically in keeping with UTI, then a sample of the urine should be sent off for microscopy, culture, and sensitivities (MC&S). These are usually referred to as a ‘mid-stream urine (MSU)’ or, if the patient is catheterised, a ‘catheter specimen of urine (CSU)’.
*Most Gram-negative bacteria will convert nitrates to nitrites so can be used as a surrogate marker for a urinary infection
Depending on the clinical picture, blood tests may be considered:
- FBC, CRP, and U&Es
- Blood cultures (for any septic patient)
- VBG (to check pH and lactate)
A bladder scan may be warranted if the patient has entered retention; if this is the case, catheterisation is typically indicated.
If pyelonephritis is suspected or in cases of recurrent UTIUs, a renal US may be required to check for obstructive causes.
Ensure the patient is well hydrated (either through PO or IV routes) and maintains a satisfactory urine output of >0.5mL/kg/hour.
Definitive management is with antibiotics; ensure to refer to your local antimicrobial prescribing guidelines for guidance, classically trimethoprim, nitrofurantoin, and co-amoxiclav are common antibiotic choices.
The majority of UTIs will resolve from the empirical treatment, yet adapt accordingly following MC&S results if poor response. Any catheterised patients with a UTI should have their catheter changed prior to starting any antibiotics.
- The classical features of a UTI are urinary frequency, urgency, dysuria, and pyrexia
- Urine dipstick +/- MCS will aid the diagnosis of a UTI
- Start empirical antibiotic therapy and ensure adequate hydration
- Change any catheter in the presence of a UTI