A 70-year-old female patient was readmitted to a local hospital with fever and chills following cardiac surgery at a major teaching institution. Blood cultures were taken and a Gram-positive coccus grew from the blood cultures within 24 hours. Initial tests indicated that this isolate was resistant to penicillin. The most likely identification is

Enterococci causes a wide variety of infections ranging from less serious, for example, urinary tract infections, to very serious, such as septicemia. A Gram-positive coccus resistant to penicillin must be assumed to be enterococcus until other more definitive biochemical testing places the isolate in one of the more esoteric groups of Gram-positive cocci. Once isolated, there are a variety of tests to speciate enterococci. However, penicillin-resistant, non-b-lactamase-producing, vancomycin-resistant, Gram-positive cocci are most likely Enterococcus faecium. There are a variety of mechanisms for vancomycin resistance in E. faecium and they have been termed Van A, B, or C. These isolates have become one of the most feared nosocomial pathogens in the hospital environment. Unfounately, no approved antibiotics can successfully treat vancomycin-resistant enterococci (VRE), only some experimental antibiotics such as Synercid. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition