Comparative assessment of antimicrobial activities of antibiotic-treated penile prostheses.
BACKGROUND
Although infections associated with penile implants are relatively infrequent, they result in serious medical consequences. Because treatment of these infections usually requires removal of the infected penile implant, prevention of infection is crucial. Since bacterial colonization of the implant is a prelude to clinical infection, antimicrobial modification of the devices may inhibit device colonization and subsequent infection.


OBJECTIVE
We compared the spectrum and durability, both in vitro and in vivo, of two antibiotic-treated penile prostheses: InhibiZone implants pre-impregnated with minocycline and rifampin (M/R) and Titan implants dipped in vancomycin.


METHODS
1×1-cm cylinder segments of (1) control untreated, (2) M/R-impregnated, and (3) vancomycin-dipped implants were studied. Baseline zones of inhibition (ZI) were determined against clinical isolates, including methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), vancomycin-resistant Enterococcus (VRE), and Escherichia coli. In addition, ZI against methicillin-susceptible S. aureus were compared both in vitro after being washed in a flow chamber and after subcutaneous implantation in rabbits for 1, 2, 7, and 14 d.


METHODS
ZI were measured as the diameter of the clear zone around each test device minus the external diameter of the device.


CONCLUSIONS
Implants pre-impregnated with M/R displayed a broader spectrum of antimicrobial activity than vancomycin-dipped implants against both gram-positive and -negative bacteria. The M/R-impregnated devices also yielded significantly larger zones of inhibition against S. aureus than vancomycin-dipped implants, both in vitro (p<0.003) and in vivo throughout the 14-d period of device implantation in rabbits (p≤0.03).


CONCLUSIONS
Penile prostheses impregnated with M/R have a broader spectrum in vitro and a more durable antimicrobial activity in vitro and in an animal model than implants dipped in vancomycin. Therefore, along with being a more practical model for incorporating antimicrobials onto the device, the use of implants pre-impregnated with M/R may help reduce the incidence of penile implant infection.
Mansouri
Mohammad D
MD
Michael E. DeBakey Veterans Affairs Medical Center, Baylor College of Medicine, The Methodist Hospital, Houston, Texas 77030, USA. mdmansouri@aol.com
Boone
Timothy B
TB
Darouiche
Rabih O
RO
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004343:Drug Implants / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004359:Drug Therapy, Combination; D016983:Enterococcus / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D004927:Escherichia coli Infections / Q000188:drug therapy; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008911:Minocycline / Q000494:pharmacology*; D015917:Penile Prosthesis / Q000009:adverse effects / Q000382:microbiology*; D016459:Prosthesis-Related Infections / Q000188:drug therapy*; D011817:Rabbits; D012293:Rifampin / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000188:drug therapy; D013212:Staphylococcus epidermidis / Q000187:drug effects; D014640:Vancomycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D004343:Drug Implants; D014640:Vancomycin; D008911:Minocycline; D012293:Rifampin