The inflatable penile prosthesis (IPP) was first introduced 50 years ago. Since then, implant infection has been a major concern of prosthetic surgeons due to the significant morbidity associated with this issue. In response, surgeons and implant manufacturers have worked tirelessly to decrease infection rates, resulting in innovations like antibiotic impregnated/coated implants, the no-touch technique, preoperative skin prep, intraoperative irrigation, and perioperative intravenous antibiotic prophylaxis.

In 2008 the AUA released the Best Practice Statement (BPS) on urologic procedures and antibiotic prophylaxis, which recommended an aminoglycoside plus vancomycin or a 1st/2nd generation cephalosporin for prosthetic cases.¹ These recommendations were extrapolated from orthopedic and general surgery literature due to an absence of prosthetic urology literature on the topic at that time.¹ This well-intentioned but unsupported publication led to extensive changes in urologic practice, including a substantial increase in the use of intravenous vancomycin and gentamicin perioperative prophylaxis.²

Over the last several years, prosthetic urologists have begun to critically assess the organisms causing implant infections and evaluate the performance of the AUA BPS recommendations.³ In 2017, Gross and colleagues identified that methicillin-resistant Staphylococcus aureus (MRSA) accounted for about 10% of implant infections.⁴ Thus, they also found vancomycin provided superior gram-positive coverage than cephalosporins.⁴ The authors also found that vancomycin plus gentamicin only covered 86% of implant pathogens.⁴ A few years later, Gross and colleagues reported that 12% of IPP infections were fungal,⁵ leading many prosthetic urologists to add antifungal agents to their antimicrobial prophylaxis regimens.

In 2020 the AUA updated the BPS but declined to change the recommended regimens in spite of new data.⁶ The BPS authors acknowledged the growing incidence of fungal implant infections but stopped short of recommending antifungal prophylaxis.⁶ Shortly after publication of the updated BPS, Rezaee et al found a higher incidence of implant infections among diabetic patients who received AUA-recommended antibiotic prophylaxis.⁷

We formed the Prosthetic Urology Multi-Institutional Partnership in 2021, which consists of prosthetic urologists from 18 institutions in North America, Europe, and Korea. Among our many endeavors^8,9 was an evaluation of the efficacy of the AUA BPS among all patients undergoing primary penile implant surgery. In a retrospective study of 4161 patients, we found vancomycin plus gentamicin was associated with a greater risk of infection compared to all other antibiotic regimens (HR: 2.7; CI 1.4 to 5.4; P = 0.004).¹⁰ Further, we demonstrated antifungal prophylaxis in addition to antibacterial coverage resulted in a 92% reduction in infection risk.¹⁰ We also compared low-dose 80 mg gentamicin to weight-based dosing and found no difference in infection risk, although this study was likely underpowered to compare gentamicin dosing. Our findings in this area are hypothesis generating and should encourage prosthetic urologists to continue to question and evaluate different aspects of IPP antimicrobial prophylaxis.

The body of literature questioning the efficacy of vancomycin plus aminoglycosides for IPP antimicrobial prophylaxis continues to grow. The ideal regimen remains elusive, and no studies to date have identified the best prophylactic regimen. To successfully answer this question, thousands of patients would need to be enrolled in a randomized controlled trial. In the absence of a clear recommendation, we advocate for a thoughtful and individualized approach to antimicrobial selection.¹¹ A simple strategy is to tailor antibiotics to local resistance patterns using local infection history and antibiograms. We applied this system to 3 surgeons at 3 separate institutions with interesting findings.¹¹

We found 3 different ideal regimens for these 3 surgeons. Only 1 regimen consisted of vancomycin plus any aminoglycoside for antibacterial coverage.¹¹ Interestingly, at 1 center we found superior coverage for Pseudomonas with tobramycin over gentamicin.¹¹ Urologists often associate aminoglycosides exclusively with gentamicin as it is the most frequently used aminoclycoside,² but our work demonstrates that this is not a safe assumption.¹¹ The final surgeon’s ideal gram-negative coverage consisted of piperacillin/tazobactam due a predominance of extended-spectrum beta-lactamase infections with high resistance to aminoglycosides.¹¹ We also advocate for the use of antifungal coverage in addition to antibacterial prophylaxis given our Prosthetic Urology Multi-Institutional Partnership group findings.¹⁰ Future work is needed to assess the performance of this tailored approach on infection prevention.

Although it may be comforting to imprudently follow societal guidelines, it is imperative for urologists to understand the foundation of these recommendations and also stay current with the newest literature. It has become clear that vancomycin plus gentamicin may not provide the best reduction in infection risk. A more tailored approach can be accomplished by using local antibiograms to sharpen the coverage picture by accounting for resistance patterns.

Disclosures: The views expressed herein are those of the authors and do not necessarily reflect the official policy or position of the Defense Health Agency, Brooke Army Medical Center, Wilford Hall Ambulatory Surgical Center, the Department of Defense, nor any agencies under the US government.