20 Penile Implant Bacterial Biofilm Profiles Vary by Surgery Indication: An Opportunity to Focus on Peri-operative Care
Authors: Chung PH , Leong JY , Phillips CD , Henry GD 
Published: April 2022

ABSTRACT

Introduction
The risk for device infection with penile implant revision surgery varies by indication (i.e., mechanical, erosion, infection). Dislodged biofilm from an existing implant is suspected to play a part to the increased risk for infection with revision surgery. An improved understanding of the existing biofilm of commons scenarios may help to guide the selection of peri-operative antibiotics, increase the inclination to replace a compromised device, and potentially lead to improved patient outcomes.

Objective
To compare bacterial biofilm profiles between implants removed due to mechanical failure, erosion, and infection using 16s rRNA next-generation sequencing (NGS).

Methods
A retrospective review was performed of 110 patients who underwent penile implant removal with or without replacement. At the time of explant, devices were swabbed with sterile gauze which was sent for NGS testing (MicroGen Diagnostics, Lubbock, TX, USA). NGS involved quantitative PCR and sequencing using Illumina MiSeq technology. Microorganism species identifications and relative abundances were documented. Differences in number of species detected (richness) and species diversity (expressed as the exponential function of the Shannon diversity metric) across samples explained by surgical indication, age, race, diabetes status, or implant duration were assessed using ANOVA. Differences in microbiome compositional profiles among samples were calculated as Bray-Curtis community dissimilarities and Permutational Analysis of Variance was used to test for the effect of the sample variables considered in ANOVA. Statistical analyses were performed using R statistical software.

Results
Of 110 total implants, 83 had complete data and were included in this study. Indication for device removal included mechanical (n=70), erosion (n=5), and infection (n=8). Species richness and microbiome compositional profiles varied by surgical indication, but not by age, race, diabetes status, or implant duration. The most frequent organisms by mechanical, erosion, and infectious indication for revision surgery were Escherichia coli, Staphylococcus epidermidis, and Pseudomonas aeruginosa, respectively. The highest relative abundant organisms by mechanical, erosion, and infectious indication for revision surgery were E. coli, Corynebacterium Jeikeium, and P. aeruginosa, respectively. Relative abundances of species that were significant through differential abundance testing comparing indication types are exhibited in Figure 1. Antibiotic resistance genes were evaluated with quantitative PCR and detected tetracycline resistance from an infected device and methicillin resistance from an eroded device.

Conclusions
Bacterial composition of implants varied by indication for surgical removal. Mechanical failure implants had a high presence of E. coli, eroded implants exhibited skin flora, and infected implants demonstrated P. aeruginosa. This information may help to guide optimal peri-operative antibiotic selection. Additional studies will help to further characterize these differences and establish whether common antibiotic combinations for prophylaxis, irrigation, and implant coatings should be altered. Further developments are also needed to help decrease post-operative infection as antibiotic and hydrophilic coatings are not sufficient for sterilizing the implant against biofilm long-term.

Disclosure
Yes, this is sponsored by industry/sponsor: MicrogenDx

Clarification
Industry funding only - investigator initiated and executed study