Perinephric abscess due to a coagulase-negative Staphylococcus: case report and review of the literature.

Perinephric abscess is an uncommon urinary tract infection that usually is caused by Staphylococcus aureus as a single pathogen or gram-negative bacilli as part of a polymicrobial process. We describe a man who presented with a right perinephric abscess due to coagulase-negative Staphylococcus as the only pathogen. The patient had bilateral nephrolithiasis, and he was treated successfully with percutaneous drainage of the abscess and parenteral antibiotics. Coagulase-negative staphylococci are increasingly reported to cause serious infections. This organism can no longer be routinely dismissed as a contaminant or colonizer. Repeated isolation of coagulase-negative Staphylococcus in the absence of other pathogens must be considered a high risk situation.