Acute prostatitis is swelling and irritation (inflammation or infection) of the prostate gland that develops rapidly.

Acute prostatitis is usually caused by a bacterial infection of the prostate gland. Any bacteria that can cause a urinary tract infection can cause acute bacterial prostatitis, including:

• Enterococci
• Escherichia coli
• Klebsiella pneumonia
• Proteus mirabilis
• Pseudomonas aeruginosa
• Staphylococcus aureus

Some sexually transmitted diseases (STDs) can cause acute prostatitis, typically in men younger than age 35. These STDs include:

• Chlamydia
• Gonorrhea
• Trichomonas
• Ureaplasma urealyticum

Prostatitis from an STD usually comes soon after sexual contact with an infected partner.

In men older than age 35, E. coli and other common bacteria typically cause prostatitis. E. coli prostatitis may occur spontaneously or after:

• Epididymitis
• Urethritis
• Urinary tract infections

Acute prostatitis may also develop from problems involving the urethra or prostate, such as:

• Bladder outlet obstruction
• Catheterization or cystoscopy
• Prostate biopsy
• Trauma
• Phimosis
• Anal (rectal) intercourse
• Transurethral surgeries

Prostatitis is rare in young boys. Men ages 20 - 35 who have multiple sexual partners are at an increased risk. Also at high risk are those who engage in anal intercourse, especially without using condoms.

Men age 50 or older who have an enlarged prostate (benign prostatic hyperplasia) are at increased risk for prostatitis due to their risk of urinary tract infection.