Assessment of Prostatic Tissue Concentration of Ertapenem After a Pre-operative Administration

Inclusion Criteria: * Acceptance and understanding of the consent form (signed) * 18-80 years old patients * BPH needing endoscopic resection according to French Urology Association recommendations * Procedure and follow up made in investigator center * normal digital rectal examination * PSA : * patient \> 69 years old, not necessary * patient \< 69 years old, PSA\<20 and if 4\<PSA\<20, the ratio free PSA/total PSA must be \>10% * patient with renal clearance \>60 estimated with MDRD * patient affiliated to the social security Exclusion Criteria: * personal or familial history of prostatic or genito-urinary cancer * personal history of pelvic irradiation * personal history of hormone-therapy * personal history of prostatic adenomectomy by abdominal approach * personal history of allergy to beta-lactamines * urinary tract infection or bacterial colonisation at the time of procedure * carbapenems treatment in the two weeks before surgery * hyperresponsivness to ertapenem or other carbapenems antibiotic * patient with renal clearance estimated with MDRD \<60 * patient with catheter or probe permanently