Diagnosis of catheter-associated UTI in adults

Consider the diagnosis of catheter-associated urinary tract infection (CA-UTI) in catheterised patients with signs and symptoms of UTI, including new onset or worsening fever (38°C or higher), rigors, acute deterioration of mental state in the absence of other causes, flank pain, acute haematuria and pelvic discomfortBonkat, 2024. For possible causes of acute deterioration of mental state, see Delirium.

The incidence of bacteriuria associated with an indwelling urinary catheter is between 3 and 10% per dayBonkat, 2024Chenoweth, 2016Lo, 2014. Therefore, after a month, almost all patients with a catheter will have bacteriuriaBonkat, 2024National Institute for Clinical Excellence (NICE), 2018. Asymptomatic catheter-associated bacteriuria rarely results in adverse outcomesKizilbash, 2013. Do not screen for or treat catheter-associated asymptomatic bacteriuria except in specific circumstances – see Asymptomatic bacteriuria in nonpregnant adults.

Bacteriuria, pyuria, and cloudy or malodorous urine are not reliable signs of CA-UTI in the absence of genitourinary symptomsBonkat, 2024. Inappropriate investigation (with urinalysis or urine culture) of asymptomatic patients can result in the incorrect diagnosis and treatment of CA-UTI. Bacteriuria and pyuria in patients with a urinary catheter should be interpreted with caution and other causes of symptoms should be considered. Absence of pyuria in a symptomatic catheterised patient suggests a diagnosis other than UTI.

Note: Do not perform urinalysis or urine culture in catheterised patients with nonspecific symptoms for CA-UTI.

For patients with suspected CA-UTI, obtain a urine sample for microscopy, culture and susceptibility testing before starting antibiotic therapy. For a guide to collecting urine samples in patients with indwelling urinary catheters, see Guide to collecting urine samples in patients with indwelling urinary catheters.

Figure 1. Guide to collecting urine samples in patients with indwelling urinary catheters

Remove the indwelling catheter and obtain a midstream urine sample.

OR (if ongoing catheterisation is required)

Replace the catheter [NB1], then collect a urine sample from the port in the drainage system, or if this is not possible, by separating the catheter from the drainage system.

Do not collect a urine sample from the drainage bag for culture.

Ensure the pathology request clearly indicates that the urine sample provided for testing was obtained via a catheter.

Note:

NB1: The catheter must be replaced before collecting the urine sample to avoid culture of bacteria present in the biofilm of the catheter but not in the bladder.