This study will examine if a single dose of Ciprofloxacin and Trimethoprim/Sulfamethoxazole are equivalent for prophylaxis immediately prior to prostate biopsy, when a patient has a suspected prostate cancer.

Background: The number of prostate biopsies are estimated to approximately 1.000.000 each year I Europe1. The infection rates after transrectal prostate biopsy are increasing annually2. The most common antibiotic used for prophylaxis is Ciprofloxacin, however, Trimethoprim/Sulfamethoxazole is also a feasible alternative3.

Aim: To evaluate the best antibiotic prophylaxis prior to trans rectal prostate biopsy in low risk patients.

Outcome: Hospitalization for infection within 14 days from biopsy.

Method: By randomization of all eligible patients with low risk of infectious complications. Patient and treating physician is blinded to treatment allocation. By using the nationwide and full coverage national patient register (NPR), mandatory for inpatient care4. All patients can be identified by the Swedish personal identification number5. Both patients related baseline characteristics is gathered through register linkages. To validate the outcome variables, for all patients admitted to hospital within 14 days will be subject for chart review. Comparing all patients from the participating units, having a code specific to trans rectal biopsy, and comparing to the excluded patients as well as included patients, will make a separate exclusion analysis.

The standard operating procedure for randomization is that patients will fill a form and informed consent of participation prior to the planned biopsy. If no exclusion criteria are filled and informed consent obtained, patient will be randomized through a web based randomization program, where only date of biopsy, earlier prostate biopsy, number of biopsies, PSA and prostate size is collected. Other baseline variables will be obtained by cross linkage to the NPR and the National Prostate Cancer Registry. A randomization number is given to all patients at this stage and a key code is established at each participating unit containing every patient randomization number and subsequent personal identification number.

After complete requirement, data will be collected at Västernorrlands Läns Landsting and analyzed according to protocol.

Analysis will be made by logistic regression and point estimates with Single sided 97.5% Confidence Interval. Sample size is calculated to require 2800 patients assuming a 0.5% frequency of infections, able to detect a difference of 0.75% in absolute proportion of infections.

Missing data on outcome variable, received treatment or date of biopsy will be excluded from analysis.

Inclusion Criteria:

• Indication for trans rectal prostate biopsy (Physicians discretion)
• Informed consent

Exclusion Criteria:

• Diabetes Mellitus
• Indwelling urinary catheter
• Prior urinary infection (last 6 months)
• Dipstick positive (Nitrites test)
• Allergy to Ciprofloxacin or Trimethoprim/Sulfamethoxazole
• Severe liver disease
• Concomittant use of Tizanidine
• Immunosuppression