Diagnosis

Recommendation

Clinical signs and symptoms compatible with CA-UTI should be used to diagnose infection in catheterised patients with urine culture and sensitivity testing employed to confirm the diagnosis and pathogen.

Good practice point

Clinical scoring tools and decision aids may be considered to aid assessment of clinical signs and symptoms.

Urine culture in symptomatic catheterised patients and use of clinical criteria-based decision aid tools are common in clinical practice in Scotland. A specific decision aid for diagnosis and management of suspected UTI in people with indwelling catheters is available from SAPG (https://www.sapg.scot/media/4570/decision-aid-for-management-of-cauti.pdf).

The shared aetiology among all people with CA-UTI may allow greater overlap in diagnostic and management strategies between the sexes. Most signs and symptoms in catheterised patients with bacteriuria are non-specific and to prevent unnecessary antibiotic use, patients should be thoroughly evaluated for the source of signs and symptoms before attributing them to the urinary tract. The presence of bacteria in the urine of catheterised patients is common and inevitable but ASB does not necessarily indicate presence of infection.

Statements from Infectious Diseases Society of North America

The following statements are reproduced, with permission, from The Infectious Diseases Society of America (IDSA) guideline which provides useful advice to support diagnosis of CA-UTI in women and men.¹²⁴

• CA-UTI in patients with indwelling urethral, indwelling suprapubic, or intermittent catheterisation is defined by the presence of symptoms or signs compatible with UTI with no other identified source of infection along with ≥103 CFU/mL of ≥1 bacterial species in a single catheter urine specimen or in a midstream voided urine specimen from a patient whose urethral, suprapubic, or condom catheter has been removed within the previous 48 hours.
• Signs and symptoms compatible with CA-UTI include new onset or worsening of fever, rigors, altered mental status, malaise, or lethargy with no other identified cause; flank pain; costovertebral angle tenderness; acute haematuria; pelvic discomfort; and in those whose catheters have been removed, dysuria, urgent or frequent urination, or suprapubic pain or tenderness.
• In catheterised patients, pyuria (presence of pus in the urine) is not diagnostic of CA-bacteriuria or CA-UTI.
  • The presence, absence, or degree of pyuria should not be used to differentiate catheterassociated asymptomatic bacteriuria (CA-ASB) from CA-UTI.
  • Pyuria accompanying CA-ASB should not be interpreted as an indication for antimicrobial treatment.
  • The absence of pyuria in a symptomatic patient suggests a diagnosis other than CA-UTI.
• In the catheterised patient, the presence or absence of odorous or cloudy urine alone should not be used to differentiate CA-ASB from CA-UTI or as an indication for urine culture or antimicrobial therapy.

All patients with a long-term indwelling catheter will have bacteria in their urine and will test positive for nitrite and leucocytes even in the absence of CA-UTI, rendering dipstick testing less sensitive to the detection of clinically significant bacteriuria. No evidence was identified for or against use of dipstick testing in patients with indwelling catheters and symptoms suggestive of CA-UTI.

Good practice point

Urinary dipsticks should not be used as part of the diagnostic assessment for UTI in patients
with indwelling catheters.

Evidence - See section 6.1 of full guideline