Urinary Tract Infection in Males Differential Diagnoses

Diagnostic Considerations

One of the difficulties in diagnosing urinary tract infections (UTIs) in males lies in the fact that dysuria, with or without discharge, is the typical chief complaint with urethritis, which is a much more common disease. Determining the history of urinary and genital tract symptoms and sexual encounters, combined with laboratory testing of urine and urethral swabs, should allow differentiation of the 2 conditions. Absence of bacteruria despite symptoms of frequency, urgency, or dysuria suggests urethritis. However, bacteruria may be symptomatic or asymptomatic.

In males aged 15-50 years, UTI is more common in males with anatomic abnormalities; in the sexually active male with no urinary tract abnormalities, sexually transmitted disease (STD) – related urethritis predominates, although UTI may occasionally be diagnosed.

In elderly patients, the typical manifestations of UTI may be absent or replaced by vague findings of failure to thrive or worsening mental status. In addition, failure to consider an obstructing urinary calculus in this patient population results in delay of inpatient consultation with a urologist in the septic elderly patient.

Patients with diabetes and those with recent urinary tract instrumentation, recent hospitalization, or taking broad-spectrum antibiotics have an increased incidence of resistant organisms.

Pyuria

The differential diagnoses for infectious causes of sterile pyuria include perinephric abscess, urethral syndrome, chronic prostatitis, renal tuberculosis, and fungal infections of the urinary tract, including C neoformans and Coccidioides immitis.

Noninfectious causes of pyuria include uric acid and hypercalcemic nephropathy, lithium and heavy metal toxicity, sarcoidosis, interstitial cystitis, polycystic kidney disease, genitourinary malignancy, and renal transplant rejection.

Prostatitis

Prostatitis can coexist with benign prostatic hyperplasia (BPH) and prostate cancer. The symptom complex of BPH and chronic prostatitis overlap; older men are sometimes misdiagnosed with one or the other. In addition, prostatitis can increase prostate-specific antigen levels, raising the concern for prostate cancer.

Young men have a very low incidence of UTI; if UTI is diagnosed frequently in this population, the physician is probably overlooking the far more likely sexually transmitted disease (STD)–related urethritis/prostatitis.

Epididymitis

Among patients with acute scrotum, 90% of cases are caused by epididymitis, torsion of the spermatic cord, and torsion of a testicular appendage. Bacteria and leukocytes observed on a urethral Gram stain support a diagnosis of epididymitis, although some overlap may be observed between epididymitis, torsion of the spermatic cord, and torsion of a testicular appendage.

Consultation with a urologist is mandatory in all but the most clear-cut cases for operative salvage of the torsed testicle. Torsion of the spermatic cord must be assumed until proven otherwise, because unresolved torsion of the cord is likely to result in irreversible necrosis in less than 12 hours.

Cystitis

In men older than 50 years, the presentation of cystitis is difficult to differentiate from that of obstructive prostatism due to prostatic hyperplasia, transitional cell carcinoma of the bladder, or acute or chronic bacterial prostatitis. In young men, urolithiasis, bladder cancer, and strictures are included in the differential diagnoses.

Microscopic hematuria is found in approximately half of cystitis cases; when found without symptoms or pyuria, it should prompt a search for malignancy. Other factors to be considered in the differential diagnoses include calculi, vasculitis, renal tuberculosis, and glomerulonephritis. In a developing country, hematuria is suggestive of schistosomiasis, which can be associated with salmonellosis and squamous cell malignancies of the bladder.

Emphysematous and xanthogranulomatous pyelonephritis

Emphysematous pyelonephritis is an infection caused by gas-forming organisms. It results in a necrotizing infection of the renal and perirenal tissue. This process occurs mostly in patients with diabetes. Glucosuria enhances organism fermentation and carbon dioxide production. Obstruction of the upper urinary tract by calculi or necrotic renal papillae is common in this condition. The mortality rate for this complication is reported to be 43%. E coli is the most common pathogen, followed by Klebsiella and Proteus.

Intraparenchymal gas can be seen on imaging studies. This is distinctly different from gas occurring in the collecting system per se, which is not infrequent in pyelonephritis and is associated with a much better prognosis. Of emphysematous pyelonephritis cases, 10% are bilateral. Prompt treatment with antibiotics and nephrectomy or surgical drainage is required.

Xanthogranulomatous pyelonephritis is a rare, but severe, renal infection that is clinically difficult to differentiate from renal tumors. It can progress to nonfunction and swelling of the involved kidney, and it is often associated with obstructing calculi. Proteus is the most common pathogen, followed by E coli. A granulomatous reaction with suppuration results in destruction and swelling of the renal parenchyma.

Although no distinguishing characteristics can be observed upon imaging, the diagnosis can be made by examining cytologic specimens; the lipid material collects in macrophages (xanthoma cells). Pus and debris may fill the collecting system, creating the condition known as pyonephrosis.

Tuberculosis

Tuberculosis may involve the prostate, but epididymitis is the most common presentation of male genital tuberculosis. The testis and seminal vesicles may also be involved. A palpable mass is present in most cases. Ironically, although patients may present with infertility, tuberculosis may be spread by semen.

Differential Diagnoses

• Appendicitis
• Chlamydial Genitourinary Infections
• Chronic Pelvic Pain Syndrome and Prostatodynia
• Pancreatitis, Acute
• Pneumonia, Bacterial
• Prostate Hyperplasia, Benign
• Prostatitis, Bacterial
• Pyelonephritis, Acute
• Pyelonephritis, Chronic
• Sepsis, Bacterial
• Tuberculosis of the Genitourinary System
• Urinary Diversions and Neobladders
• Urinary Tract Obstruction
• Vesicoureteral Reflux
• Xanthogranulomatous Pyelonephritis