• Follow local guidelines, when these are available.
• Do not treat asymptomatic bacteriuria.
• Considerable clinical judgement is required to diagnose urinary tract infection (UTI) in men with an indwelling urinary catheter.
• If symptoms are severe (for example severe nausea and vomiting, confusion, tachypnoea, tachycardia, hypotension, reduced urine output), admit the person to hospital; intravenous antibiotics may be required.
• Check that the catheter is correctly positioned and is not blocked. If the catheter has been in place for more than a week, consider changing it before starting antibiotic treatment.
• If there is fever or loin pain (or both), manage as upper UTI. See the CKS topic on Pyelonephritis - acute.
• Otherwise, treat for lower UTI.
• Relieve symptoms with paracetamol or ibuprofen.
• Before starting antibiotic treatment, obtain a urine sample for culture and microscopy.
• Treat with an antibiotic for 7 days.
• If symptoms are mild, consider withholding antibiotics until the result of urine culture is available to guide choice of antibiotic.
• If treatment cannot wait for the culture results, start empirical treatment with trimethoprim or nitrofurantoin.
• Trimethoprim 200 mg twice daily, for 7 days. Trimethoprim should not be used for empirical treatment if the man has a history of recurrent infections or has taken trimethoprim within the past 12 months.
• Nitrofurantoin 50 mg four times daily, or 100 mg (modified-release) twice daily, for 7 days. The standard formulation is suitable for most people. Consider prescribing the modified-release formulation if nausea has previously been troublesome with the standard formulation, or if adherence with taking medication four times daily is likely to be poor.
• Follow up after 48 hours (or according to the clinical situation) to check response to treatment and the urine culture results.

Using clinical judgement to decide when to use antibiotics

• Careful clinical judgement is recommended when deciding to use an antibiotic in people with an indwelling urinary catheter. This is because all people with a long-term indwelling urinary catheter will have bacteriuria at some stage, there is no good evidence that antibiotics are beneficial for asymptomatic bacteriuria, and repeated treatment of asymptomatic bacteriuria increases the risk of colonization by drug-resistant bacteria [SIGN, 2006; European Association of Urology, 2009].

Admitting to hospital

• The recommendation to admit the person to hospital if systemic symptoms and signs are present is based on expert opinion [SIGN, 2006].

Reviewing catheter care

• The recommendation to review the care of the catheter is based on expert opinion [NICE, 2003; European Association of Urology, 2009].
• The recommendation to consider changing the catheter before starting antibiotic treatment for urinary tract infection (UTI) is based on one small trial and expert opinion [SIGN, 2006; European Association of Urology, 2009]. See the evidence in the CKS topic on Urinary tract infection (lower) - women.

Using urine culture to guide the choice of antibiotic

• The recommendation to use the culture results to guide treatment and, if practical, to withhold treatment until the culture results are available, is based on expert opinion. It is intended to reduce the risks of complications and treatment failure, which are generally increased in people with an indwelling urinary catheter [SIGN, 2006].
• The recommendation to change to a more appropriate antibiotic if the antibiotic was started empirically and a resistant organism is isolated on urine culture is based on expert opinion. It is intended to reduce the risks of complications and treatment failure [SIGN, 2006; European Association of Urology, 2009].

Relieving symptoms

• CKS found no trials of analgesics for relieving the symptoms of UTI. The recommendation to use paracetamol or ibuprofen to treat the symptoms of UTI is based on their use in other painful infections and the experience of experts [SIGN, 2006].

Choosing an antibiotic

• As there is no direct evidence from clinical trials of different antibiotics in men with an indwelling urinary catheter, the recommendation to prescribe trimethoprim or nitrofurantoin for empirical treatment of UTI is based on the recommendations in the Treatment section of Managing lower UTI in men.

Treating for 7 days

• Antibiotic treatment for 7 days is recommended because there is only one small trial of treatment duration. Although this found that shorter courses are equally effective for UTI in people with an indwelling urinary catheter, further studies are required to support a recommendation for a shorter course. See the evidence in the CKS topic on Urinary tract infection (lower) - women.