Antibiotic prophylaxis for primary penile implantation tied to higher infection risk

Antibiotic prophylaxis with vancomycin plus gentamicin alone for primary inflatable penile prosthesis surgery results in a higher risk of infection compared to nonstandard antibiotic regimens, suggests a recent study. On the other hand, antifungal use appears to reduce infection risk.

A team of investigators conducted a multicentre, retrospective study of patients undergoing primary inflatable penile prosthesis surgery. Participants were grouped into two: those receiving vancomycin plus gentamicin alone and those receiving other regimens.

The investigators generated a Cox proportional hazards model, adjusted for major predictors. They also performed a subgroup analysis to identify the correct dosage of gentamicin.

Overall, 4,161 patients underwent primary inflatable penile prosthesis placement, of which 2,411 received vancomycin plus gentamicin alone and 1,750, other regimens. Similar rates of infection were observed between the two cohorts (1.0 percent vs 1.2 percent, respectively).

Multivariable analysis revealed that vancomycin plus gentamicin (hazard ratio [HR], 2.7, 95 percent confidence interval [CI], 1.4‒5.4; p=0.004) and diabetes (HR, 1.9, 95 percent CI, 1.03‒3.4; p=0.04) significantly correlated with an increased infection risk. In contrast, antifungals (HR, 0.08, 95 percent CI, 0.03‒0.19; p<0.001) resulted in a lower risk of infection.

Moreover, no statistically significant difference in infection rate was seen between weight-based gentamicin compared to gentamicin 80 mg (HR, 2.9, 95 percent CI, 0.83‒10; p=0.1).

“A critical review of the recommended antimicrobial prophylactic regimens is needed,” the investigators said. “Prospective research is needed to further elucidate best practices in inflatable penile prosthesis antimicrobial prophylaxis.”