46.1 Acute Prostatitis, Epididymitis & Orchitis

Epidemiology & Pathophysiology of Acute Bacterial Prostatitis (ABP)

Acute bacterial prostatitis (National Institutes of Health [NIH] Category I) is a severe, acute infectious illness of the prostate gland that accounts for approximately 5% to 10% of all prostatitis presentations in primary care. Unlike non-bacterial chronic pelvic pain syndromes (NIH Category III), ABP represents an active, life-threatening parenchymal infection demanding rapid diagnostic recognition and prolonged bactericidal therapy.

NIH Classification of Prostatitis Syndromes

To avoid diagnostic confusion, the NIH categorizes prostatitis into four distinct entities:

• Category I: Acute Bacterial Prostatitis (ABP) — Acute systemic bacterial infection of the prostate gland.
• Category II: Chronic Bacterial Prostatitis (CBP) — Recurrent urinary tract infections caused by the same bacterial pathogen persisting within the prostatic parenchyma or calculi.
• Category III: Chronic Prostatitis / Chronic Pelvic Pain Syndrome (CP/CPPS) — Perineal or pelvic pain for >=3 months without identifiable bacterial infection (Subtype IIIa: Inflammatory [leukocytes in semen/EPS]; Subtype IIIb: Non-inflammatory).
• Category IV: Asymptomatic Inflammatory Prostatitis — Incidental finding of inflammatory cells in prostatic secretions or histology in the absence of genitourinary symptoms.

Microbiologic Etiology

The microbiologic spectrum of acute bacterial prostatitis mirrors that of complicated ascending urinary tract infections:

• Gram-Negative Enteric Coliforms (>90% of cases):
  • Escherichia coli: The predominant causative pathogen, accounting for 80% to 85% of all community-acquired cases.
  • Klebsiella pneumoniae: 3% to 5%.
  • Proteus mirabilis: 3% to 5% (frequently associated with alkaline urine and struvite calculi).
  • Enterobacter aerogenes / cloacae and Serratia marcescens: 2% to 3%.
• Healthcare-Associated & Resistant Pathogens:
  • Pseudomonas aeruginosa: Seen particularly after transurethral instrumentation, indwelling urethral catheterization, or recent transrectal prostate biopsy.
  • Enterococcus faecalis (Gram-positive) and Staphylococcus aureus (including MRSA, often via hematogenous dissemination from distant infectious foci or injection drug use).
  • Sexually transmitted pathogens (Neisseria gonorrhoeae, Chlamydia trachomatis) are rare causes of isolated acute prostatitis, though they frequently cause concurrent urethritis and epididymo-orchitis in men younger than 35 years.

Pathogenesis & The Route of Infection

The predominant mechanism of infection is retrograde ascent of infected urine from the posterior urethra into the prostatic branched tubuloalveolar ducts, often facilitated by high intraurethral voiding pressures against an unrelaxed external sphincter (urinary reflux). Bacteria adhere to the prostatic ductal epithelium, colonize the glandular acini, and induce intense microvascular congestion, intraprostatic edema, polymorphonuclear infiltration, and microabscess formation. The resultant dramatic swelling of the prostate gland compresses the prostatic urethra, leading to secondary bladder outlet obstruction and acute urinary retention.

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Clinical Presentation & Physical Examination

Patients with acute bacterial prostatitis characteristically present with an explosive, rapidly progressive clinical constellation of systemic toxicity combined with severe lower urinary tract irritation and voiding obstruction.

Cardinal Symptoms

1. Systemic Toxicity: Abrupt high fevers (temperature often >38.5°C [101.3°F]), shaking chills, diaphoresis, generalized arthralgias, myalgias, nausea, and profound malaise.
2. Irritative Lower Urinary Tract Symptoms (LUTS): Severe dysuria, marked urinary frequency, urgency, and nocturia, secondary to trigonal and posterior urethral inflammation.
3. Obstructive Voiding Symptoms: Hesitancy, straining, weak or split urinary stream, terminal dribbling, sensation of incomplete emptying, and frank acute urinary retention resulting from mechanical compression of the urethra by the swollen, edematous prostate.
4. Pain Distribution: Deep-seated, throbbing ache localized to the perineum, sacrococcygeal spine, suprapubic area, or low back. Pain is characteristically exacerbated by sitting, defecation (due to fecal compression against the posterior prostate), or ejaculation.

Digital Rectal Examination (DRE) & The Cardinal Safety Warning

[!CAUTION] CRITICAL CLINICAL PEARL: PROSTATIC MASSAGE IS STRICTLY CONTRAINDICATED Vigorous, forceful, or repeated digital manipulation or massage of the prostate is STRICTLY CONTRAINDICATED in suspected acute bacterial prostatitis.

Applying mechanical compression to an acutely infected, hyperemic prostate forces massive inocula of bacteria into the friable prostatic venous plexus and pudendal circulation, directly precipitating bacteremia, septic shock, and hematogenous seeding. Furthermore, manual compression risks retrograde dissemination through the vas deferens, causing acute secondary epididymo-orchitis or capsular rupture. DRE must be performed with extreme gentleness purely to establish the diagnosis.

• Gentle DRE Technique & Findings:
  • Perform an exceptionally gentle, single-finger digital examination.
  • The acutely infected prostate is palpated as exquisitely tender, hot/warm to the touch, swollen, tense, and boggy (soft and spongy).
  • The normal median sulcus is frequently effaced by bilateral lobar swelling.
  • If focal fluctuation or severe asymmetric asymmetry is noted, a prostatic abscess must be strongly suspected.

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Diagnostic Evaluation & Laboratory Workup

                     DIAGNOSTIC TRIAGE FOR ACUTE PROSTATITIS

   Diagnostic Test          Expected Finding                     Clinical Pitfall / Pearl
   ═════════════════════════════════════════════════════════════════════════════════════════════
   Midstream Urinalysis     Pyuria (>10 WBC/HPF), leukocyte       Essential first step; bacteriuria
                            esterase (+), nitrites (+), hematuria confirms infected urinary tract.

   Urine Culture &          Growth of >=10^5 CFU/mL coliform      Mandatory in ALL suspected cases;
   Susceptibility           (typically E. coli)                   guides targeted de-escalation.

   Serum PSA                Markedly elevated (often >20 ng/mL)   DO NOT ORDER in acute phase;
                            due to architectural disruption       remains elevated for 4-6 weeks.

   Blood Cultures (x2 sets) Positive in 20-30% of febrile cases;  Mandatory if febrile, toxic, or
                            identifies bacteremia                 admitted to inpatient service.

   Bedside Bladder US       Elevated post-void residual volume    Identifies acute urinary retention;
                            (often >300-500 mL)                   guides cautious decompression.
   ═════════════════════════════════════════════════════════════════════════════════════════════

Laboratory Workup

• Clean-Catch Midstream Urinalysis: Typically reveals marked pyuria, positive leukocyte esterase, positive nitrites, and variable microscopic hematuria. Unlike chronic prostatitis (which requires the Meares-Stamey 4-glass localization test or 2-glass pre/post-massage test), a simple midstream specimen in ABP is heavily colonized and diagnostic.
• Urine Culture and Susceptibility: An absolute standard of care in every suspected case of ABP. Culture identifies the organism and provides minimum inhibitory concentrations (MICs) to confirm susceptibility to fluoroquinolones and TMP-SMX.
• Blood Cultures: Two sets of peripheral blood cultures must be drawn in all patients with systemic fevers, hemodynamic instability, or those requiring hospitalization.
• Serum Prostate-Specific Antigen (PSA):
  • Acute inflammatory disruption of the prostatic epithelial-stromal barrier allows leakage of massive amounts of PSA into the systemic circulation, often elevating serum PSA to >20 to 50 ng/mL.
  • Clinical Warning: Serum PSA should never be measured during an acute episode of prostatitis to screen for prostate cancer. Testing during active infection generates false-positive alarms, causes profound patient distress, and leads to inappropriate biopsies. If an incidental PSA was drawn, it should be repeated no earlier than 4 to 6 weeks after complete resolution of the infection.

Emergency Management of Acute Urinary Retention in ABP

Prostatic swelling frequently precipitates acute urinary retention. Urethral catheterization must be approached with extreme caution:

• Transurethral catheterization through a severely inflamed, friable prostatic urethra can cause severe mucosal trauma, intolerable pain, and hematogenous bacteremia.
• If bladder decompression is required, a gentle attempt with a small-caliber (12 to 14 French) soft silicone Foley catheter may be performed by an experienced clinician.
• If any resistance is encountered or the patient experiences agonizing pain, do not force the catheter. Immediate percutaneous suprapubic cystostomy (placed by urology under ultrasound guidance) is the preferred, safe method to drain the bladder while completely bypassing the infected prostate.

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Antimicrobial Pharmacotherapy & Tissue Penetration

Treating bacterial prostatitis presents a unique pharmacokinetic challenge because the prostate is protected by a physiological blood-prostate barrier similar in function to the blood-brain barrier.

Pharmacokinetics of Prostatic Penetration

During acute inflammation, increased vascular permeability temporarily permits hydrophilic drugs (such as beta-lactams and aminoglycosides) to enter the prostatic interstitium. However, within 48 to 72 hours of antimicrobial initiation, local inflammation subsides, the prostatic capillary endothelium reconstitutes its tight junctions, and the blood-prostate barrier is re-established. To achieve therapeutic bactericidal concentrations within the prostatic acini and lipid-rich stroma, an antimicrobial must possess:

1. High lipid solubility (allowing passive diffusion across epithelial membranes);
2. Low plasma protein binding (maximizing free drug fraction);
3. A favorable ionization constant (pKa) that facilitates "ion trapping" within the acidic environment of prostatic fluid (prostatic fluid pH ~6.5 to 7.0 vs serum pH 7.40).

Only two oral antibiotic classes reliably satisfy these rigorous criteria: Fluoroquinolones and Trimethoprim-Sulfamethoxazole (TMP-SMX).

                  ANTIMICROBIAL REGIMENS FOR ACUTE BACTERIAL PROSTATITIS

   Clinical Setting      Preferred Regimen                    Dosage & Route      Mandatory Duration
   ═════════════════════════════════════════════════════════════════════════════════════════════════
   Outpatient            Ciprofloxacin                        500 mg PO BID       4 to 6 WEEKS
   (Mild-to-moderate,    OR Levofloxacin                      500 mg PO daily     (MANDATORY FULL
   hemodynamically       OR Trimethoprim-Sulfamethoxazole     1 DS tablet PO BID  COURSE)
   stable, tolerating    (TMP-SMX 160/800 mg)                 (if susceptible)
   oral fluids)          

   Inpatient             Ampicillin PLUS Gentamicin           2 g IV q6h +        Step-down to oral
   (High fevers,         OR Ceftriaxone                       5 mg/kg IV q24h;    quinolone once
   hemodynamic           OR Levofloxacin                      1-2 g IV daily;     afebrile for 48 hr;
   instability, sepsis,  OR Ciprofloxacin                     750 mg IV daily;    complete 4 to 6
   urinary retention)    OR Piperacillin-Tazobactam           400 mg IV q12h;     WEEKS total
                         (if hospital-acquired/Pseudomonas)   3.375 g IV q6h      therapy
   ═════════════════════════════════════════════════════════════════════════════════════════════════

Why a Mandatory 4 to 6 Weeks of Therapy?

[!IMPORTANT] THE 4-TO-6-WEEK ANTIMICROBIAL MANDATE Primary care clinicians must prescribe a FULL COURSE OF 4 TO 6 WEEKS of targeted antimicrobial therapy for acute bacterial prostatitis, even if the patient becomes completely asymptomatic and afebrile within 48 to 72 hours.

Short antibiotic courses (e.g., 7 to 14 days, as used for uncomplicated pyelonephritis or cystitis) result in an unacceptably high rate of treatment failure (>50%). Inadequate duration allows viable bacteria to hide within obstructed prostatic canaliculi and calcified corpora amylacea, creating chronic bacterial prostatitis (Category II) or a frank prostatic abscess, which requires surgical intervention and months of suppressive therapy.

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Prostatic Abscess: Diagnosis & Urologic Intervention

A prostatic abscess is a localized collection of purulent fluid within the prostate parenchyma. It arises as a direct complication of untreated or inadequately treated acute bacterial prostatitis.

Clinical Suspicion & Red Flags

A prostatic abscess should be strongly suspected in any patient with ABP who exhibits:

• Persistent fever, chills, or leukocytosis after 48 to 72 hours of appropriate, culture-directed intravenous or oral antimicrobial therapy;
• Worsening pelvic, perineal, or rectal pain despite therapeutic compliance;
• Recurrent or progressive urinary retention;
• A fluctuant, tender mass or asymmetrical softening palpated during a repeat, exceptionally gentle digital rectal examination.

High-Risk Patient Populations

Prostatic abscess is disproportionately encountered in men with:

• Poorly controlled diabetes mellitus (impaired neutrophil chemotaxis and microvascular perfusion);
• Chronic immunosuppression (HIV/AIDS, solid organ transplantation, chronic corticosteroid therapy);
• Chronic indwelling urethral Foley catheters or intermittent clean catheterization;
• Recent transrectal ultrasound-guided prostate needle biopsy.

Diagnostic Imaging & Surgical Management

• Diagnostic Modality of Choice:
  • Transrectal Ultrasound (TRUS): Highly accurate for defining the exact location, volume, and internal septations of the abscess, visible as single or multiple hypoechoic, thick-walled fluid cavities. TRUS is contraindicated if the patient has extreme rectal pain or anal strictures.
  • Contrast-Enhanced Pelvic CT or Pelvic MRI: Indicated when TRUS is contraindicated or if periprostatic, levator ani, or ischiorectal fossa extension is suspected.
• Intervention:
  • Abscesses <1 cm in diameter without systemic sepsis may occasionally resolve with prolonged intravenous antibiotics alone.
  • Abscesses >=1 to 2 cm, or those accompanied by severe sepsis, mandate active drainage:
    • Transurethral Unroofing / Resection: Transurethral resection of the prostate (TURP) roof covering the cavity allows immediate, wide-open drainage into the prostatic urethra.
    • Transrectal or Transperineal Needle Aspiration: Performed under real-time TRUS or CT guidance; fluid is aspirated completely and sent for Gram stain, culture, and sensitivities.

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Acute Epididymitis & Orchitis

Acute epididymitis is an inflammation of the epididymis characterized by scrotal pain, erythema, and progressive swelling lasting fewer than 6 weeks. In up to 60% of cases, the inflammatory process spreads to the adjacent testicle, producing acute epididymo-orchitis.

Pathophysiological Mechanism

The primary pathophysiologic mechanism is retrograde intraurethral ascent of microorganisms from the bladder neck, prostate, or urethra along the ejaculatory duct and vas deferens into the coiled tubules of the epididymis. Straining against a closed bladder neck, heavy lifting with a full bladder, or vigorous physical exertion can generate transient high retrograde pressures that drive infected urine through the vas deferens into the tail (globus minor) of the epididymis.

              AGE-STRATIFIED MANAGEMENT OF ACUTE EPIDIDYMITIS

   Patient Category        Primary Microbial Etiologies     First-Line Guideline Antimicrobial Regimen
   ═════════════════════════════════════════════════════════════════════════════════════════════════════
   Sexually Active Men     Chlamydia trachomatis            Ceftriaxone 500 mg IM in a single dose*
   Aged < 35 Years         Neisseria gonorrhoeae            PLUS Doxycycline 100 mg PO BID x 10 days
                           (Sexually Transmitted)

   Men Aged >= 35 Years    Enteric Coliforms                Levofloxacin 500 mg PO once daily x 10-14 days
   OR Post-Catheterization (Escherichia coli,               OR Ciprofloxacin 500 mg PO BID x 10-14 days
   OR Post-Instrumentation  Klebsiella, Pseudomonas)

   Men Practicing          Dual Etiology:                   Ceftriaxone 500 mg IM single dose*
   Insertive Anal Sex      Enteric Coliforms (E. coli)      PLUS Levofloxacin 500 mg PO daily x 10 days
   (Any Age)               PLUS C. trachomatis / N. gon     (covers coliforms + STIs)
   ═════════════════════════════════════════════════════════════════════════════════════════════════════
   *Note: For patients weighing >= 150 kg (330 lbs), Ceftriaxone dose should be increased to 1,000 mg (1 g) IM.

Clinical Presentation & Physical Examination

• Onset & Evolution: Unlike testicular torsion (which begins abruptly in seconds to minutes), epididymitis develops gradually over 24 to 72 hours.
• Symptoms: Unilateral scrotal ache that radiates up the spermatic cord into the ipsilateral flank or groin, progressive scrotal enlargement, dysuria, urethral discharge (in sexually transmitted cases), and fever (present in 25% to 35% of cases).
• Physical Examination:
  • Early: Marked induration, tenderness, and swelling isolated strictly to the posterior aspect of the testis along the epididymis (starting at the tail).
  • Late: Inflammation envelops the entire testicle (epididymo-orchitis) with an inflammatory reactive hydrocele, making physical distinction between the testis and epididymis impossible.
  • The Cremasteric Reflex: Intact and brisk in epididymitis. Lightly stroking the superior-medial thigh produces elevation of the ipsilateral testis (>0.5 cm). An intact cremasteric reflex strongly argues against testicular torsion.
  • Prehn Sign: Passive manual elevation of the painful hemiscrotum over the pubic symphysis relieves pain (positive Prehn sign) due to temporary reduction in venous and gravitational tension on the epididymal pedicle.

[!WARNING] CLINICAL ALERT: PREHN SIGN CANNOT EXCLUDE TESTICULAR TORSION Although a positive Prehn sign is historically taught as suggestive of epididymitis, prospective surgical studies demonstrate that Prehn sign has low specificity and can be falsely positive in patients with partial or intermittent testicular torsion.

Clinicians must NEVER rely upon Prehn sign alone to rule out testicular torsion. In any post-pubertal adolescent or young adult presenting with acute scrotal pain, urgent Color Doppler Scrotal Ultrasound is mandatory unless the clinical picture is unequivocally typical of an STI in an older patient with normal anatomy and a clear timeline.

Diagnostic Workup for Epididymitis

1. Urine Testing: Midstream urinalysis and urine culture (identifies enteric coliforms in men >=35).
2. Urethral Swab or First-Catch Urine Nucleic Acid Amplification Testing (NAAT): Mandatory in sexually active men <35 or those with risk factors; tests for Neisseria gonorrhoeae, Chlamydia trachomatis, and Mycoplasma genitalium (patient must not have voided within 1 to 2 hours prior to collection).
3. Color Doppler Scrotal Ultrasound: The definitive imaging study. Confirms acute epididymitis by demonstrating an enlarged, hyperemic epididymis with markedly increased blood flow (hypervascularity) on color and power Doppler, preserved or increased testicular perfusion, and frequently an associated reactive hydrocele with thickened scrotal wall.

Supportive Management

In addition to targeted antimicrobial therapy:

• Strict bed rest for 48 to 72 hours during the peak acute phase;
• Scrotal elevation and immobilization: Use of an athletic supporter (jockstrap) or a rolled towel placed beneath the scrotum while recumbent dramatically decreases venous tension;
• Cold ice packs applied to the scrotum for 20 minutes at a time (never apply ice directly to skin);
• Scheduled oral non-steroidal anti-inflammatory drugs (NSAIDs; e.g., Naproxen 500 mg PO BID) for pain relief and soft tissue anti-inflammatory action;
• Sexual partner notification: Partners from the preceding 60 days must be referred for evaluation and empiric treatment, and the patient must abstain from sexual contact until both partners complete therapy and symptoms resolve.

Isolated Viral Orchitis: Mumps & Systemic Pathogens

Isolated orchitis (testicular inflammation without primary epididymal involvement) is overwhelmingly viral in origin, with Mumps (paramyxovirus) serving as the classic prototypical pathogen.

Mumps Orchitis

• Epidemiology: Occurs in 20% to 30% of post-pubertal adolescent and adult males afflicted with mumps parotitis. It is extremely rare in prepubertal boys (<10 years old).
• Clinical Presentation:
  • Develops acutely 4 to 7 days after the onset of bilateral or unilateral painful parotitis (swelling and erythema anterior to the ear and over the angle of the mandible).
  • Abrupt high fevers (up to 40°C [104°F]), shaking chills, severe headache, nausea, and excruciating unilateral (70-80%) or bilateral (20-30%) testicular pain and massive scrotal enlargement.
  • Physical examination reveals a shiny, erythematous, tense hemiscrotum with a profoundly enlarged, exquisitely tender testis; the epididymis is typically spared or only mildly reactive.
• Complications & The Fertility Threat:
  • Testicular Atrophy: Seen in 30% to 50% of affected testes within 1 to 6 months post-infection, secondary to pressure-induced necrosis caused by tunica albuginea inelasticity during severe parenchymal edema.
  • Impairment of Spermatogenesis: Abnormal sperm count, decreased motility, and elevated abnormal forms occur in up to 30% of cases. However, permanent complete sterility is uncommon, occurring in <1% to 2% of bilateral cases, because Leydig cell function and some seminiferous tubules are usually preserved.
• Management & Prevention:
  • No specific antiviral therapy exists; management is strictly supportive (strict bed rest, scrotal suspension, ice compresses, NSAIDs, or narcotics for severe intractable pain).
  • Prevention: High two-dose coverage with the Measles-Mumps-Rubella (MMR) live-attenuated vaccine (first dose at age 12-15 months, second dose at age 4-6 years).