eMedicine Specialties > Urology > Infections and Related Inflammatory Conditions

Acute Bacterial Prostatitis and Prostatic Abscess

Author: Jonathan J Rhee, MD, Staff Physician, Department of Urology, University of Virginia
Coauthor(s): Michael Piesman, MD, Staff Physician, Department of Internal Medicine, Madigan Army Medical Center; Raymond A Costabile, MD, Jay Y Gillenwater Professor of Urology, University of Virginia Health System
Contributor Information and Disclosures

Updated: Dec 5, 2008

Introduction

Acute prostatitis presents as an acute urinary tract infection in men. It is much less common than chronic prostatitis but is easier to identify because of its more uniform clinical presentation. Chronic prostatitis, which now has several classifications, is poorly understood partly because of its uncertain etiology and lack of clearly distinguishing clinical features.

Acute prostatitis is usually associated with predisposing risk factors, including bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH) or an immunosuppressed state. This review focuses on acute bacterial prostatitis (ABP).

History of the Procedure

In 1978-1979, symptoms due to acute and chronic prostatitis accounted for 25% of outpatient urinary conditions. In 1985, according to Nickel, acute and chronic prostatitis accounted for more office visits than BPH or prostate cancer. Most of these visits were for chronic prostatitis. In the early 1990s, the diagnosis of prostatitis resulted in slightly more than 2 million office visits per year.

Problem

Pathologically, prostatitis is defined as an increased number of inflammatory cells within the prostate gland. The inflammatory process may be infectious or inflammatory in origin. The most common histologic pattern is a lymphocytic infiltrate in the stroma immediately adjacent to the prostatic acini.¹ Prostatitis occurs in distinct forms that have separate causes, clinical features, and outcomes. Four clinical entities have been described: acute bacterial prostatitis, chronic bacterial prostatitis, nonbacterial or abacterial prostatitis, and prostatodynia.

The National Institutes of Health (NIH) classification and definition of the categories of prostatitis are as follows:

• Category I - Acute bacterial prostatitis, ie, acute infection of the prostate
• Category II - Chronic bacterial prostatitis, ie, recurrent urinary tract infection and/or chronic infection of the prostate
• Category III - Chronic abacterial prostatitis/chronic pelvic pain syndrome, ie, discomfort or pain in the pelvic region for at least 3 months with variable voiding and sexual symptoms and/or no demonstrable infection (By definition, the syndrome becomes chronic after 3 mo.)
• Category IIIA - Inflammatory chronic pelvic pain syndrome, ie, white blood cells in semen and/or expressed prostatic secretions and/or third midstream bladder specimen
• Category IIIB - Noninflammatory chronic pelvic pain syndrome, ie, no white blood cells in semen and/or expressed prostatic secretions
• Category IV - Asymptomatic inflammatory prostatitis, ie, evidence of inflammation in biopsy samples, semen and/or expressed prostatic secretions, and no symptoms

Frequency

Using data from the National Ambulatory Medical Care Surveys (NAMCS), Collins et al (1998) found that prostatitis was listed as the diagnosis in almost 2 million US physician visits annually from 1990-1994.² Prostatitis is the most common urologic diagnosis in males younger than 50 years and the third most common diagnosis in men older than 50 years (after BPH and prostate cancer). However, acute prostatitis is rare. Approximately 5% of cases of acute bacterial prostatitis progress to chronic bacterial prostatitis.³

The international prevalence rate of prostatitis is similar to that in the United States. Of 600 men diagnosed with prostatitis, 5% had bacterial prostatitis, 64% had nonbacterial prostatitis, and 31% had pelvic-perineal pain syndrome or prostatodynia.

Etiology

Most prostatic infections (82%) involve only a single bacterial organism. In some cases, 2 or 3 strains of bacteria may be involved. The organisms primarily responsible for acute bacterial prostatitis are also those responsible for most urinary tract infections.

The most common causal organisms of acute bacterial prostatitis include gram-negative members of the Enterobacteriaceae family. They include Escherichia coli, Proteus mirabilis, Klebsiella species, Enterobacter species, Pseudomonas aeruginosa, and Serratia species. Of these, E coli is involved most often and has been shown to increase biofilm formation.⁴

Obligate anaerobic bacteria and gram-positive bacteria other than enterococci rarely cause acute bacterial prostatitis. Enterococci account for 5-10% of documented prostate infections.⁵ Staphylococcus aureus infection due to prolonged catheterization may occur in the hospital. Other occasional causative organisms include Neisseria gonorrhea, Mycobacterium tuberculosis, Salmonella species, Clostridium species, and parasitic or mycotic organisms. N gonorrhea should be suspected in sexually active men younger than 35 years.

If recurrent urinary tract infections are confirmed, patients need to be evaluated for structural abnormality.

Pathophysiology

Several theories exist regarding the pathogenesis of acute bacterial prostatitis.

• Intraprostatic urinary reflux: This theory is the most widely accepted. Infected urine refluxes into the ejaculatory and prostatic ducts that empty into the posterior urethra. Because of the anatomy of the prostate gland, ducts that drain glands in the large peripheral zone are positioned more horizontally than other prostatic ducts and, thus, facilitate the reflux of urine into the prostate. Consequently, most infections occur in the peripheral zone.
• Ascending urethral infection: In younger men, ascending urethral infection may occur following sexual intercourse. Meatal inoculation may occur during unprotected anal intercourse, instrumentation, and prolonged catheterization.
• Direct invasion or lymphogenous spread from the rectum
• Direct hematogenous infection
• The following are risk factors for acute bacterial prostatitis (all allow bacterial colonization):
  • Intraprostatic ductal reflux
  • Phimosis and redundant foreskin
  • Specific blood groups⁶
  • Unprotected anal intercourse
  • Urinary tract infections
  • Acute epididymitis
  • Indwelling Foley catheter and condom catheter
  • Transurethral surgery
  • Altered prostatic secretions

Presentation

Acute bacterial prostatitis usually presents as an acute illness with moderate to severe fever, chills, low back and perineal pain, urinary frequency and urgency, nocturia, dysuria, and generalized malaise. Arthralgia and myalgia may accompany these symptoms. Acute bacterial prostatitis may also result in acute urinary retention due to varying degrees of bladder outlet obstruction. The diagnosis of acute bacterial prostatitis is based primarily on clinical findings, in association with positive results on urinalysis and urine culture.

In patients with acute bacterial prostatitis, rectal palpation usually reveals an enlarged, exquisitely tender, swollen prostate gland, which is firm, warm, and, occasionally, irregular to the touch. Care must be taken to avoid vigorous prostatic massage in a patient with suspected acute bacterial prostatitis to prevent bacteremia and sepsis.

Sexual dysfunction is described as a symptom of chronic prostatitis and chronic pelvic pain syndrome. Pain associated with ejaculation (which translates to impaired overall quality of life) contributes to or causes erectile dysfunction.⁷

Indications

Prostatic abscess, which is an uncommon but well-described complication of acute bacterial prostatitis (ABP), is a potential indication for surgery. Medical management of prostatic abscess is often unsuccessful.Transrectal or perineal aspiration of the abscess is preferred and is often effective, especially if symptoms do not improve after 1 week of medical therapy. Transurethral resection of the prostate and drainage of the cavity is another approach. However, this approach is less desirable because of the potential hematogenic spread of bacteria.

Relevant Anatomy

The prostate is an extraperitoneal organ that encircles the neck of the bladder and urethra and weighs approximately 20 g in a healthy man. The adult prostate is divided into 4 distinct zones or regions: the periurethral, central, transitional, and peripheral zones. Carcinoma arises more often in the peripheral zone. However, the distribution of prostatic inflammation among the various zones is not clear.

Histologically, the prostate gland is composed of tubuloalveolar glands. The glandular spaces are lined by epithelium, which is composed of 2 layers of cells—a basal layer of low cuboidal epithelium covered by a layer of columnar mucus-secreting cells. The glands have a distinct basement membrane and are separated by a fibromuscular stroma.

Contraindications

Prostate biopsy is contraindicated in patients with suspected acute bacterial prostatitis (ABP) because of the potential complication of seeding the bacterial infection in adjacent organs. Furthermore, prostate biopsy is extremely painful without a prostatic nerve block. The current practice is to anesthetize the area prior to core biopsy sampling. Biopsy in the face of acute bacterial prostatitis may result in gram-negative sepsis.

Because of the potential for systemic infection and bacteremia, urethral instrumentation should be avoided in patients with acute bacterial prostatitis, especially if the patient is unstable or is already showing signs of sepsis, although placement of a small drainage catheter is safe in experienced hands. Pretreatment with appropriate antibiotics is mandatory.

Transurethral or perineal surgical approaches in the treatment of a prostatic abscess should be undertaken with caution and are currently not advised unless other drainage techniques have failed. Perineal incision can cause impotence due to nerve injury, and transurethral resection can elicit hematogenous spread of bacteria, leading to sepsis.⁸

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