Cavernous tissue antibiotic levels in penile prosthesis surgery

A comparison of the delivery of several antibiotics (vancomycin, gentamicin and aztreonam) to the tissue site of prosthesis implantation was studied using cavernous tissue levels for each antibiotic. A total of 32 patients underwent penile prosthesis implantation. Intravenous antibiotics were administered 1 to 2 hours preoperatively, with vancomycin and aztreonam given to patients at the Tulane University Medical Center, and vancomycin and gentamicin given to patients at the New Orleans Veterans Administration Hospital. At operation the urine, serum and cavernous tissue were concurrently sampled and later analyzed for antibiotic concentration. The mean cavernous tissue level for vancomycin was 55.5 ± 5.5 ng./mg. (standard deviation) for 20 patients, while the mean cavernous tissue levels for aztreonam and gentamicin were 8.9 ± 2.1 ng./mg. for 10 patients and 4.7 ± 1.2 ng./mg. for 12 patients, respectively. When the delivery of antibiotic to cavernous tissue was compared (quantitated as ng. antibiotic per mg. tissue per mg. drug administered), a statistically significant value (p <0.01) was observed with vancomycin (0.11 ng./mg./mg.) greater than gentamicin (0.06 ng./mg./mg.) or aztreonam (0.01 ng./mg./mg.), and with no significant difference observed between aztreonam or gentamicin. These findings suggest that cavernous tissue levels may be used as a method to determine optimal antibiotic prophylaxis against penile prosthesis infection.