Microbiological evaluation of infected pelvic lymphocele after robotic prostatectomy: potential predictors for culture positivity and selection of the best empirical antimicrobial therapy.

Objectives: To examine symptomatology and microbiology of infected lymphocele (LC) post-robotic-assisted radical prostatectomy and pelvic lymph node dissection (PLND) and to assess for potential predictors for LC fluid culture positivity. Secondly, to provide general recommendations about use of select antimicrobial therapy.

Methods: This was a single-center, IRB-approved, retrospective, case series review conducted between October 2008 and October 2014. Data included symptomatology, microbiology of symptomatic LC in men post-robotic prostatectomy and PLND. Those with infected LC were compared to those men with symptomatic LC in the absence of infection.

Results: Symptomatic LC was seen in 7% of men, and among those, infected LC was seen in 42%. Infected LC cultures showed predominance of G+ cocci such as S. aureus, coagulase-negative Staphylococcus species, S. pyogenes, S. fecalis and S. viridans. Monomicrobial infection was seen in 85%. Multivariate logistic regression showed leukocytosis [Odds: 12.3, p = 0.03, 95% CI (1.2-125)] was significant predictor for culture positivity, whereas trend toward significance for factors such CT findings of thickened walls around the LC +/- air.

Conclusions: LC infection following PLND for prostate cancer is usually monomicrobial and caused by Gram+ cocci. GI tract and skin flora are the main habitat. High index of suspicion of infected LC is undertaken in the presence of leukocytosis, fever and abnormal CT findings. Based upon our local hospital antibiogram, combination of IV ampicillin/sulbactam and vancomycin is suggested as the best initial empiric therapy in treating these patients.