(130) Antibiotic Solutions are the Ideal Irrigation Choice for Inflatable Penile Implant Hydrophilic Surfaces

Introduction

Inflatable penile prostheses (IPP) may be colonized by bacteria, which may contribute to clinical infections. Current attempts to reduce bacterial colonization include altered implant surface binding properties and mechanical irrigations with antiseptic solutions. Previous data has shown that prophylactically dipping IPPs in a solution of 2mg/mL vancomycin and 160μg/mL gentamicin (VG) reduces biofilm formation more than chlorhexidine gluconate (CHG) does. However, there is a paucity of data looking at VG as an irrigation step after a prophylactic dip.

Objective

To determine if VG irrigation of a previously CHG- or NS-dipped IPP decreases bacterial colonization more effectively than irrigation with normal saline.

Methods

Sterile 8mm diameter IPP pieces (Coloplast, Minneapolis, MN) were split into 4 groups with a minimum of 12 replicates each and submerged for 3 minutes in 3mL of normal saline (NS), 0.05% CHG in sterile water (Irrimax, Lawrenceville, GA), or VG (Sigma-Aldrich, Burlington, MA). Pieces were then rinsed in NS for five seconds, re-submerged in a separate well containing 2mL of NS or VG for 2 minutes, and finally rinsed for five seconds in a large volume of NS. After a 5 sec PBS rinse, pieces were incubated with 1 X 10^5 colony forming units per milliliter (CFU)/mL of methicillin-sensitive Staphylococcus aureus ATCC25923 in trypticase soy broth (TSB) for 48 hours. Samples were then rinsed with PBS and biofilm was removed by shaking in 0.3% Tween-20. Suspended bacteria were serially diluted, plated onto 3M PetriFilms (Maplewood, MN), and then colony counts were recorded. Mann-Whitney U tests were performed to compare outcomes, p<0.05 considered significant.

Results

Average bacterial counts with 95% CI are plotted in Figure 1. NS controls showed an average of 1.0E7 CFU/mL adherent bacteria. In this study, the introduction of VG to an NS or CHG-coated implant resulted in significant reduction in adherent bacteria; the NS-VG group showed a ~5 log decrease in adherent bacteria (3.0E1, standard deviation=3.3E4, p<0.01), and the CHG-VG group similarly showed a ~5 log decrease in adherent bacteria (4.4E2, standard deviation=6.9E5, p<0.01). Neither treatment group consistently reduced biofilm counts as effectively as the implant pieces incubated in VG as both a prophylactic dip and a rinse solution (~5 log decrease in counts, p<0.01). However, neither treatment group consistently reduced biofilm counts as effectively as the implant pieces incubated in VG as both a prophylactic dip and a rinse solution, also with a ~5 log decrease in adherent bacteria (1.0E2, standard deviation=2.4E2, p<0.01) (Figure 1).

Conclusions

VG is the ideal choice for both coating the implant prior to implantation and as an intraoperative irrigation solution. However, further studies are needed to compare VG with CHG as mechanical irrigants as opposed to static irrigants.

Disclosure

Yes, this is sponsored by industry/sponsor: Coloplast (material not financial support).

Clarification: Industry funding only - investigator initiated and executed study.

Any of the authors act as a consultant, employee or shareholder of an industry for: Coloplast and Boston Scientific.