Which of the following organisms is most likely to cause infection in this following case?

Probably because of its ubiquity and ability to stick to foreign surfaces, S. epidermidis is the most common cause of infections of central nervous system shunts as well as an impoant cause of infections on aificial hea valves and ohopedic prostheses. Corynebacterium spp. (diphtheroids), just like S. epidermidis, colonize the skin. When these organisms are isolated from cultures of shunts, it is often difficult to be sure if they are the cause of disease or simply contaminants. Leukocytosis in cerebrospinal fluid, consistent isolation of the same organism, and the character of a patient's symptoms are all helpful in deciding whether treatment for infection is indicated. Ref : Ananthanarayana textbook of Microbiology 9th edition Pgno : 205