• Follow local guidelines, when these are available.
• If symptoms are severe (for example severe nausea and vomiting, confusion, tachypnoea, tachycardia, or hypotension), admit the person to hospital; intravenous antibiotics may be required.
• If there is fever or loin pain (or both), manage as upper urinary tract infection (UTI) — see the CKS topic on Pyelonephritis - acute.
• Otherwise, treat for lower UTI:
• Obtain a urine sample for culture and microscopy before starting antibiotic treatment.
• Relieve symptoms with paracetamol or ibuprofen.
• 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.

These recommendations are based on guidelines from the Scottish Intercollegiate Guidelines Network (SIGN), the Health Protection Agency (HPA), and the European Urological Association (EUA) [SIGN, 2006; HPA and Association of Medical Microbiologists, 2008; European Association of Urology, 2009]. Because urinary tract infection (UTI) in men is rare, there are no controlled trials. These guidelines are therefore based on expert opinion or extrapolation from studies in women with UTI.

Obtaining a urine sample before starting treatment

• Obtaining a urine sample for culture and sensitivity before starting treatment is recommended:
• To confirm UTI — urine dipstick tests are not sufficiently accurate. This recommendation is pragmatic, and is extrapolated from the evidence on the use of urine dipstick tests to diagnose lower UTI in women. Recent UK national and European guidelines do not discuss the use of urine dipstick tests for men with suspected UTI [SIGN, 2006; HPA and Association of Medical Microbiologists, 2008; European Association of Urology, 2009]. A recent systematic review and meta-analysis of urine dipstick tests to exclude UTI found that only one of 23 studies was done in men, and reported results combined from all studies without regard to gender [St John et al, 2006].
• To guide the choice of antibiotic — resistance to first-line antibiotics is not uncommon, and infections with multi-resistant Escherichia coli with extended-spectrum beta-lactamase enzymes (ESBL) are increasing [HPA and Association of Medical Microbiologists, 2008].

Empirical treatment with trimethoprim or nitrofurantoin

• There is no evidence from clinical trials of antibiotics for lower UTI in men. Therefore, recommendations are based on evidence extrapolated from treatment of lower UTI in women (which is reviewed in the CKS topic on Urinary tract infection (lower) - women) and on expert opinion.
• Choice of antibiotic
• Trimethoprim and nitrofurantoin are active against most uropathogens, and are recommended as first-line options by the Health Protection Agency (HPA) and Association of Medical Microbiologists for use in men with lower UTI and without fever and flank pain [HPA, 2009].
• Several guidelines recommend that nitrofurantoin should not be used to treat UTI in men. This is on the grounds that it can be difficult to exclude the possibility of prostatitis, and that nitrofurantoin is not present in therapeutic concentrations in prostatic secretions [SIGN, 2006; European Association of Urology, 2009]. However, these recommendations refer to UTI with fever or other signs of acute prostatitis, and neither guideline expressed concern that acute prostatitis would be likely in men with symptoms of lower UTI and without fever and other symptoms of prostatitis.
• For initial empirical treatment, the HPA and Association of Medical Microbiologists recommend not using broad-spectrum antibiotics (such as co-amoxiclav, quinolones, and cephalosporins) when narrow-spectrum antibiotics remain effective. This is because broad-spectrum antibiotics increase the risk of Clostridium difficile, meticillin resistant Staphylococcus aureus (MRSA), and the development of antibiotic resistance [HPA and Association of Medical Microbiologists, 2008].
• Trimethoprim is not recommended if the man has used it in the past 12 months because use of trimethoprim up to 1 year previously is associated with increased risk of infection with a resistant organism. The evidence is reviewed in the CKS topic on Urinary tract infection (lower) - women.
• Trimethoprim is not recommended for empirical treatment of recurrent UTI in men because of the (theoretical) increased risk that this is due to a resistant organism.
• Duration of treatment
• In contrast to the situation in women, there is no evidence that short courses are as effective as longer courses of antibiotics to treat lower UTI in men. Because men are more likely than women to have an occult complicating factor, at least 7 days of antibiotic treatment is recommended [SIGN, 2006; European Association of Urology, 2009].