Presentation Authors: Soum Lokeshwar, Laura Horodyski*, Miami, FL, Sarrah Lahorewala, Augusta, GA, Himanshu Arora, Joshua Bitran, Nicholas Hauser, Bruce Kava, Ranjith Ramasamy, Miami, FL
Introduction: Inflatable penile implants are used for treating erectile dysfunction. The AMS 700â„¢ (AMS) implant is coated with a blend of rifampin and minocycline (InhibiZone). TitanÂ® Coloplast (Coloplast) soaked in Rifampin/Gentamicin is comparable to AMS in preventing E. coli infection with in vitro studies. Intra-operative soaking of the implant with Bupivacaine is proposed as a strategy for pain control. However, no study has shown if this agent affects the protective effect of InhibiZone in AMS and/or of Rifampin/Gentamicin soaked Coloplast. We tested the hypothesis that the use of Bupivacaine does not alter the protective effect of antibiotic coating. We examined if the zone of inhibition (ZOI) against E. coli created by InhibiZone in AMS and/or by Rifampin/Gentamicin soaked Coloplast implant is altered by Bupivacaine.
Methods: E. coli was spread on LB agar plates. After a 30 minute incubation, 4 AMS InhibiZoneÂ® strips treated with saline or Bupivacaine (1 mg/ml) were placed on a plate. 4 Coloplast strips were dipped in various routinely used concentrations of Rifampin (0 â€“ 10 mg/ml) plus Gentamicin (0 â€“ 1 mg/ml) solution with or without Bupivacaine (1 mg/ml). Following 24 h and 48 h incubation, ZOI was measured using the ImageJ software. Normalized ZOI was calculated as (ZOI area/plate area) x 100. Unpaired t-test compared the mean Â± SD ZOI between Bupivacaine and no Bupivacaine groups (n = 4/group).
Results: AMS with InhibiZoneÂ® and Coloplast dipped in R+G combination inhibited E. coli growth following 24 h and 48 h incubation similarly. Coloplast strips dipped in R+G produced ZOI in a dose-dependent manner. The ZOI produced by AMS with InhibiZoneÂ® was comparable to Coloplast strips dipped in 1.25 mg/ml R plus 0.125 mg/ml G. For both implants, addition of Bupivacaine did not affect ZOI both at 24 h and 48 h incubation. AMS with InhibiZoneÂ® had a ZOI with and without Bupivacaine of 1.34 Â± 0.06 and 1.21 Â± 0.11 (p-value 0.062) at 24 h. For Coloplast 2.5/0.25 R+G combination showed a ZOI with and without Bupivacaine of 2.81 Â± 0.42 and 2.2 Â± 0.5 (p-value 0.122) at 24 h. This concentration of R+G was chosen since the ZOI produced was in the linear range and was the median of the various amounts used clinically.
Conclusions: Bupivacaine did not impede the antibacterial activity of InhibiZoneÂ® or Rifampin/Gentamicin soaked Coloplast. This suggests the use of Bupivacaine does not affect the protective effects of antibiotic dips and can be used during implant operation. Whether the in vitro findings, translate to surgical outcomes needs to be evaluated.