Propionibacterium acnes central nervous system shunt infection. Commercial blood culture medium-dependent isolation of the bacterium.

A 58-year-old woman had a central nervous system shunt infection and septicemia caused by Propionibacterium acnes. During a two-year period, many Becton-Dickinson blood cultures (18 of 39) were positive for P. acnes, but all BACTEC blood cultures (15) were negative. Parallel cultures in the two commercial media performed simultaneously on the same blood samples several times resulted in a positive Becton-Dickinson culture and a negative BACTEC culture. This case reemphasizes that some bacterial isolates may not be detected when using only one commercial blood culture medium. Thus, if many blood cultures are negative for patients who have clinical features suggestive of septicemia, other types of blood culture media should be inoculated.