A number of mechanisms have been proposed to explain the etiology and pathogenesis of prostatitis. Some, such as a microbiologic cause, clearly explain the pathogenesis of certain categories, such as acute bacterial prostatitis (ABP) and chronic bacterial prostatitis (CBP). However, a unified theory for all categories and presentations does not exist, and will likely never be found.
Categories I and II are mostly caused by gram-negative Enterobacteriaceae and enteroccoccal species that originate in the gastrointestinal flora. The most common organism is Escherichia coli, which is identified in the majority of infections.8 Pseudomonas aeruginosa, Serratia species, Klebsiella species, and Enterobacter aerogenes make up most of the rest of the gram negative cultured organisms.9
An immune cascade secondary to an infectious or a non-infectious antigen with resultant inflammation is another important etiology.10 Other possible mechanisms include neural dysregulation, interstitial cystitis-like pain, and psychological causes. Psychological variables, such a depression, maladaptive coping techniques such as pain catastrophizing, poor social support, and stress are important in chronic prostatitis outcomes.11
Patients with Category I prostatitis (ABP) present with severe lower urinary tract symptoms such as frequency, urgency, intermittency, stranguria with possible retention. Those are commonly accompanied by systemic symptoms, frequently fever and occasionally nausea and vomiting. Evaluation consists of a complete physical examination that includes a digital rectal examination (DRE) to look for a very tender, possibly boggy prostate, a urinalysis to look for evidence of infection, and a urine culture to confirm the diagnosis. A vigorous DRE in this setting is to be avoided because of the risk of systemic bacterial dissemination.
Evaluation of Categories II (CBP) and III (CP/CPPS) should incorporate at a minimum: a thorough history, a physical examination, including a DRE, urinalysis, and culture. The history should include past UTIs and a discussion of the pain (location, severity and frequency), voiding symptoms (obstructive and irritative), and the impact this condition on the patient’s activities and quality of life. To that end, the Chronic Prostatitis Symptom Index (CPSI) is a useful clinical questionnaire given that objective parameters in this condition are often lacking.12 The CPSI consists of nine questions that evaluate three domains requiring evaluation: pain, urinary function, and quality of life. The total score allows for ongoing assessment of symptom severity in a condition characterized by waxing and waning symptomology. In addition, a lower urinary tract localization test is helpful in localizing infections to the prostate. A simple 2-glass technique has been shown to be a highly effective and practical collection method to rule out infection (Category II).13 It consists of a midstream urine collection followed by collection of the first 10 cc of urine after a vigorous prostate massage. Uropathogenic bacteria localized to the post-massage specimen (meaning a higher concentration of bacteria than in the pre-massage urine or the presence of any bacteria if pre-massage urine is sterile) indicates a prostate nidus of infection (Category II).