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 >100,000 CFU/mL for organisms identified as common pathogens; however, many sites now use either 10,000 CFU/mL or 1000 CFU/mL threshold, based on the method of collection or patient population as a baseline for culture work-up and clinical significance.[43]

Urine from a man with urinary tract symptoms (dysuria, frequency, urgency, suprapubic pain, costovertebral angle pain) that grows ≥10³ colony-forming units (CFU)/mL of one, or predominantly one, organism in culture suggests the presence of UTI.​[25][44]

History

Most UTIs in men occur after 50 years of age, and the incidence is highest among those residing in long-term care facilities.

Dysuria most often results from infection.[6] 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.[25] Finally, the history includes identification of systemic signs (e.g., fever, rigors) 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:[25]

  • Previous UTI

  • Benign prostatic hyperplasia (BPH)

  • Urinary tract 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 may occur in patients with complicated 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.[2][45]​ 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.[43]​ 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.[15] Culture is essential to confirm the diagnosis of UTI and because of the potential for non-traditional organisms in men.[5][19]​ The presence of ≥10² CFU/mL of one, or predominantly one, organism in culture confirms UTI in symptomatic men. A midstream clean-catch urine sample used for culture compares favourably with suprapubic aspiration or catheter specimens.[46]

No difference exists in the approach to patients 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.[11][4]​​ But a negative U/A does exclude the presence of UTI.[4][11]​​​

Biological markers of bacterial infection, such as the myeloid cell soluble trigger receptor expression (sTREM-1), have not been a reliable method for detecting infection of the male urinary tract as a result of their low sensitivity.[42][47][48]

Imaging

Imaging of the kidneys, ureters, and bladder by computed tomography (CT), ultrasound, or intravenous urogram, should be reserved for:[1][3]

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

  • Cases of treatment failure

  • Those with persistent haematuria

  • 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.[1][3][12][13][19][26]

The healthcare provider must choose an imaging technique based on availability of local resources and the underlying pathology that is suspected. CT scan offers the best overall detail but is expensive. A plain x-ray of kidneys, ureters, and bladder can be helpful if stones are suspected, but CT scan is more reliable. If an obstructive process is suspected, ultrasound can rule this out. The intravenous urogram (IVU) has only limited usefulness compared with the other modes of imaging, but the clinician may consider obtaining an IVU if continued suspicion exists after a negative CT or ultrasound, or in cases where a less expensive test is desired.

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