Approach

There is debate over the exact number of bacteria in a urine culture that is needed to define urinary tract infection (UTI) in men. The standardised threshold in symptomatic patients is >10⁵ colony-forming units/mL (CFU/mL) for organisms identified as common pathogens; however, many sites now use either 10⁴ CFU/mL or 10³ CFU/mL threshold, based on the method of collection or patient population as a baseline for culture work-up and clinical significance.[51] In men, positive results are usually seen if there are more than 10³ CFU/mL, which is much lower than the threshold for women.[52]

A positive diagnosis of UTI in a male can be made in a symptomatic patient with urine that grows ≥10³ CFU/mL of one, or predominantly one, organism in culture.​[31]​​[52][53]

History

Dysuria most often results from localised infection.[2][8]​​​ Also, frequency, urgency, and suprapubic pain signal UTI. Costovertebral angle pain suggests extension of UTI to the kidney (pyelonephritis). Rectal or perineal pain can indicate UTI associated with prostatitis. Men may present with urethral discharge or have symptoms related to impaired urine flow, such as hesitancy or nocturia.[31] A history of cloudy or foul smelling urine can indicate a UTI.[9]​ Finally, the history includes identification of systemic signs (e.g., fever, rigors), presence of haematuria, and possible immunocompromised states (e.g., diabetes mellitus) that may indicate a more severely ill patient requiring hospitalisation.

The past medical history can reveal the following risks contributing to UTI:[31]

  • Previous UTI

  • Benign prostatic hyperplasia (BPH)

  • Bladder stones

  • Previous urological surgery or instrumentation

  • Recent hospitalisation

The social history will identify sexual practices and preferences; anal sex in particular increases risk of UTI.

Physical examination

The physical examination is useful in excluding other possible causes for the patient's symptoms. It should at least include the abdomen, genitalia, rectum, and palpation of the costovertebral angle.

A tender boggy prostate, firm enlarged prostate, or nodularity suggests prostatitis, prostate hyperplasia, and prostate cancer, respectively.

Penile lesions or discharge suggest sexually transmitted infection.

Tenderness or swelling of the epididymis or testes implies the presence of epididymitis or orchitis, respectively.

Fever is suggestive of a systemic bacterial infection, and may be seen with prostatitis, orchitis, epididymitis, pyelonephritis, or UTI.

Laboratory

A dipstick or microscopic urinalysis (U/A) is the initial test for men with suspected UTI. If dipstick is negative for nitrites and leukocyte esterase, or microscopic U/A is negative for bacteria and leukocytes, this excludes infection, but the presence of these markers does not rule in UTI.[4][54]​​​​ One Denmark study of patients presenting to the accident and emergency department found both a negative leukocyte esterase and negative nitrite had a negative predictive value of 93.3% for men.[55]​ Negative results should prompt a search for another cause of the patient's symptoms.

A positive U/A in a man with typical UTI symptoms should be followed by a urine culture and empirical antibiotic therapy while awaiting the culture result. In the absence of signs and symptoms of a UTI, a urine culture is typically not recommended.[51]​ In men with a positive U/A, obtaining a Gram stain of the urine can guide the initial antibiotic choice; however, it is not required, because empirical therapy can be chosen based on the anticipated pathogenic bacteria. Gram stain, like U/A, does not confirm the presence of UTI.[23] Culture is essential to confirm the diagnosis of UTI and because of the potential for non-traditional organisms in men.[7][19]​​​ The presence of ≥10³ CFU/mL of one, or predominantly one, organism in culture confirms UTI in symptomatic men.[56]​ A midstream clean-catch urine sample used for culture compares favourably with suprapubic aspiration or catheter specimens.[57] In the absence of signs and symptoms of a UTI, a urine culture is typically not recommended.[51]

The general approach to patients is similar in the outpatient and long-term care settings. However, in long-term care, U/A is even less predictive of the presence of UTI because a high proportion of these patients have pyuria related to asymptomatic bacteriuria.[6][16]​​​​​​ However, a negative U/A does exclude the presence of UTI.[6][16]​​​​ In patients with indwelling catheters, a urine dipstick should not be used to diagnose UTI, as catheters are usually colonised with bacteria and will likely give a positive result. Instead, a urine culture is used to support the diagnosis in a symptomatic patient.[58]

Visible or non-visible haematuria need further assessment for malignancy. See Assessment of visible haematuria and Assessment of non-visible haematuria.

Imaging

Imaging of the kidneys, ureters, and bladder by computed tomography (CT), or ultrasound should be reserved for:​[5][59][60]​​​​[61]

  • Those who have voiding dysfunction without a clearly identifiable cause such as BPH

  • Cases of treatment failure

  • Suspicion of obstruction or complication

  • Those with signs of upper tract infection.

Although imaging of men with UTI frequently results in abnormal findings, it usually does not alter treatment. Therefore, it is not indicated in all cases.​[32][59]​​[60] ​The American College of Radiology recommends that CT urography and/or ultrasound of the kidneys and retroperitoneum be considered for further evaluation in patients with raised creatinine, stones, haematuria, UTI, or other complicating history.[62][63]

The healthcare provider must choose an imaging technique based on availability of local resources and the underlying pathology that is suspected.

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