A Scoping Review of Penile Implant Biofilms

What Do We Know and What Remains Unknown?

Joon Yau Leong; Courtney E. Capella; Maria J. D'Amico; Selin Isguven; Caroline Purtill; Priscilla Machado; Lauren J. Delaney; Gerard D. Henry; Noreen J. Hickok; Flemming Forsberg; Paul H. Chung

Disclosures

Transl Androl Urol. 2022;11(8):1210-1221. 

In This Article

Abstract and Introduction

Abstract

Background: Penile prosthesis (PP) is a gold standard for treatment of erectile dysfunction given its reliability and efficacy. Infection remains the most feared complication of prosthetic surgery, which usually results in device removal, and places a significant economic burden on the healthcare system. While biofilms have shown to support the persistence of microorganisms, the degree by which this matrix is truly pathogenic remains unknown given its high prevalence even in asymptomatic patients. We aim to review and summarize the current literature pertaining to biofilm formation in the setting of PP surgeries in clinically infected and non-infected cases.

Methods: Searches were performed in the MEDLINE online database through PubMed using a combination of keywords "penile prosthetic" OR "penile prosthesis" OR "penile implant" AND "biofilm" OR "revision" OR "removal" OR "infection" OR "explant". Eleven articles met inclusion criteria. There were only three studies that explicitly listed the number of biofilms identified in their cohort, but we also included eight articles that mentioned swabbing and culturing of any bacterial biofilm during revision procedures for both clinically infected and non-infected implants.

Results: Infected PP yielded a 11–100% rate of biofilm presence, while non-infected PP yielded a 3–70% rate of biofilm presence. Time to reoperation from initial PP placement were also largely variable, ranging from 2 weeks to over 2 years. Coagulase-negative staphylococcus (i.e., Staphylococcus epidermidis) were the most commonly reported organisms among non-infected implants, however, newer studies have identified a change towards more virulent organisms.

Conclusions: Since the advent of PP surgery, diabetes control, revision washout protocols and antibiotic-impregnated devices have led to an overall decrease in biofilm formation and infectious complications. There is an overall paradigm shift in microbial profiles with more virulent organisms, such as Escherichia coli, Pseudomonas aeruginosa, Enterococcus species, and even fungal species beginning to replace the more common coagulase-negative staphylococcal species, especially in clinically infected implants. Additional studies are necessary to define the significance of bacterial presence in biofilms using impactful technologies such as next-generation sequencing. Currently, preliminary and experimental biofilm-control strategies are also underway to further address this clinical issue.

Introduction

Due to its long-term durability and high rates of patient and partner satisfaction, penile prosthesis (PP) implantation is now regarded as a gold standard treatment for medically refractory erectile dysfunction (ED).[1,2] According to the American Urological Association guidelines, PP can be considered as a first-line treatment option for ED, which differs from the previously recommended stepwise approach.[3] Recent reviews have suggested that PP implantations may not only be the most effective treatment for ED, but also the most cost effective compared to other medical therapies in specific populations, such as those after ischemic priapism.[4–6] With the growing body of literature surrounding the efficacy of PP for ED, device failure rates and surgical complications have also been well established. Of these, infection remains the most concerning sequelae, often necessitating device removal and subsequent revision surgery with suboptimal outcomes.[7]

Device infections are thought to be caused by the introduction of microorganisms via incisions at the time of surgery or via hematogenous spread. Typically, the host defense mechanisms and prophylactic antibiotics kill the bacteria; however, in the setting of medical device implantation into a surgical wound, the implant is rapidly coated with serum proteins and ultimately the body deems it as a foreign body and coats it with a conditioning layer of fibrous capsule, which can alter the surface characteristics of the inanimate object.[8] This serum-coated surface is ideal for bacterial adherence and subsequent biofilm formation (Figure 1). Bacterial biofilms are communities of adherent bacteria protected against the body's immune system and antibiotics by a protein-containing polysaccharide matrix. During this process, the cells undergo phenotypic changes that render them less metabolically active and, therefore, more drug resistant.[9] The risk of device infection is further increased after revision surgery due to weakened host-resistance factors, impaired wound healing related to scar formation and, most importantly, decreased antibiotic penetration secondary to bacterial biofilm formation.[10]

Figure 1.

Implant surfaces from devices explanted for mechanical malfunction, preserved with formalin, dried, gold sputter-coated and visualized by scanning electron microscope, (A) pump, (B) cylinder. (A) Surface features and apparent bacterial biofilms sequestered in an implant crevice; surface irregularities are favored for bacterial attachment. (B) Surface texture and extensive cellular colonization among biological debris, morphology is consistent with white cells.

Bacterial biofilms are problematic to the prosthetic surgeon and catastrophic for the patient as they are extremely difficult to prevent or treat. Within the urologic field, biofilms can cause complications with simple devices such as urethral catheters or indwelling ureteral stents, as well as PP implants. An understanding of these biofilms and the microbes they harbor is essential to understanding the pathophysiology of device infection and malfunction. Herein, we aim to provide the readership with a scoping review of the current literature pertaining to biofilm formation in the setting of PP surgeries. We present the following article in accordance with the PRISMA-ScR reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-22-195/rc).

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