(128) Characterizing Antibiotic Susceptibility of the Penile Prosthesis Microbiome
Authors: Khooblall P , Roth B , Werneburg G , Lundy S , Miller A , Bajic P 
Published: February 2024

Abstract

Introduction
Inflatable penile prostheses (IPP) are the gold standard treatment for erectile dysfunction refractory to conservative therapies. However, infection remains a significant concern and the presence of microbial biofilms on both infected and non-infected devices has recently been demonstrated. Various antimicrobials are used for prophylaxis intraoperatively and postoperatively. It remains unknown how these antimicrobials affect the growth of bacteria and their associated biofilms. We sought to assess how commonly used antimicrobials influenced growth of bacterial isolates previously isolated from both non-infected and infected devices, obtained during revisional surgery.

Objective
The goal of this study was to evaluate growth of bacterial isolates previously obtained from non-infected and infected IPPs. Isolates were exposed to single or multi-antibiotic combinations to assess degree of inhibition of bacterial growth.

Methods
In this IRB-approved study, 35 bacterial isolates had been previously obtained from patients who had been consented for IPP revision or replacement secondary to mechanical failure, pain, or device infection. Bacteria were plated on brain-heart-infusion (BHI) agar plates and allowed to incubate for 48 hours. Standard-sized antibiotic discs were introduced into the grown bacterial colonies consisting of the following single or multi-agent regimens: bacitracin, cefaclor, cephazolin, gentamicin, levofloxacin, trimethoprim-sulfamethoxazole, tobramycin, vancomycin, piperacillin/tazobactam, gentamicin + piperacillin/tazobactam, gentamicin + cephazolin, and gentamicin + vancomycin. Zones of inhibition (ZOI) were measured after placement of the antibiotic discs in the bacterial colonies. Statistics were analyzed with false discovery rate corrected, one-sample t-tests. Quantification of antibiotic resistance was defined as follows: Resistant: ZOI not significantly different from 0 in one sample t-test Susceptible: ZOI significantly greater than 0, but mean is &lt;10mm Highly susceptible: ZOI significantly greater than 0, but mean is 10-20mm Exceptionally susceptible: ZOI significantly greater than 0, but mean is &gt;20mm Taxonomic classification of bacterial isolates was provided by extracting DNA from pure cultures and sequencing the full length 16S rRNA gene using Sanger sequencing, after amplification with two different primer sets to provide overlapping sequence regions.

Results
Of the antibiotics tested, TMP-SMX was found to have the highest percentage of resistant isolates (54.3%) of the 35 tested, with bacitracin having the second most (40%). Both tobramycin and TMP-SMX had 0.0% of isolates be exceptionally susceptible. Combination piperacillin/tazobactam was found to have the highest percentage of exceptionally susceptible isolates (11.4%). A large majority of isolates were highly susceptible to gentamicin + piperacillin/tazobactam (91.4%), piperacillin/tazobactam (74.3%), gentamicin + cefazolin (74.3%), and levofloxacin (88.6%), while greater than half of isolates were highly susceptible to cefazolin (62.9%) and cefaclor (54.3%)."

Conclusions
Our results demonstrate that cefaclor or bacitracin prevented growth of bacterial isolates obtained from IPPs explanted for mechanical failure, pain or infection. Further investigation is needed to characterize how intraoperative and postoperative antibiotic influences a symbiotic or dysbiotic community of microbes on the surface of penile prostheses. By better understanding the interactions between microbes, antibiotics and host, novel therapeutics might promote a non-infected, symbiotic microenvironment.

Disclosure
Yes, this is sponsored by industry/sponsor: Coloplast corporation.
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, boston scientific.