A Multicenter Investigation Examining Timing of Penile Prosthesis Infections and Responsible Organisms
Michael E. Rezaee, MD, MPH1, Amanda R. Swanton, MD, PhD1, Martin S. Gross, MD1, Ricardo M. Munarriz, MD2.
1Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA, 2Boston Medical Center, Boston, MA, USA.
BACKGROUND: Penile prosthesis infections are thought to occur either shortly after surgery or in a delayed fashion. Differences in responsible organism pathogenicity is believed to explain why some patients present with infections later compared to others (i.e. acute vs. indolent infections). However, in the era of antibiotic-coated devices and increasing antibiotic resistance, little is known about current patterns in timing of device infections. Therefore, we sought to examine the timing of penile prosthesis infections by different responsible organisms.
METHODS: We performed a retrospective cohort study of patients who underwent penile prosthesis salvage or explant procedures due to infection between 2001 and 2018. Patients were followed for three years. The primary outcome of interest was time to penile prosthesis infection, which was defined as the number of months from initial implant to a salvage or explant procedure. Intraoperative culture data was reviewed for each infection and grouped by responsible organism, including no growth cultures, gram positives (GPs), gram negatives (GNs), yeast and anaerobes. Cox proportional hazard models were used to compare median time to infection by responsible organism and pre-operative antibiotic regimen. Chi-square analysis was used to examine the type of salvage procedure used for early (< 3 months) and delayed infections (> 3 months).
RESULTS: The study sample consisted of 225 patients from 33 implanters across 6 different countries. Intraoperative culture data showed no growth in 30.2% of cases. The most common organisms responsible for infections included GPs (31.6%), GNs (22.2%), Yeast (12.0%), and Anaerobes (4.0%). Median time to infection was 2 months and did not significantly differ by responsible organism (p=0.52): yeast (3 months), GPs (2 months), no growth cultures (2 months), anaerobes (2 months), and GNs (1.3 months, Figure 1). Infections were polymicrobial in 23.6% of cases. Median time to infection did not differ significantly between single organism (2 months) and polymicrobial infections (1 month, p=0.92). Similarly, median time to infection did not significantly differ by type of pre-operative antibiotic regimen (p=0.22). A higher proportion of patients with delayed infections underwent device explant (37.4% vs. 50.0%) and three piece salvage (25.2% vs. 28.4%) compared to those with early infections, while those with delayed infections underwent fewer malleable salvage procedures (37.4% vs. 21.6%, p=0.02).
CONCLUSIONS: Two-thirds of penile prosthesis infections occur within 3 months of surgery. Median time to device infection is similar amongst responsible organisms as well as pre-operative antibiotic regimens. These findings may suggest that more indolent infections are less common in the age of antibiotic-coated devices and increasing antibiotic resistance. 
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