Tap the spinal fluid; 20% will have normal fluid (PubMed).
Having a shunt?
Staphylococcus, coagulase negative (found in 37% of specimens), Staphylococcus aureus (18%), and Propionibacterium acnes (9%), the rest were a variety of gram negative rods (PubMed). Holding the cultures for two weeks will increase the yield (PubMed).
If you grow a colon organism like an E. coli, the peritoneal end of the shunt has eroded into bowel. I have seen it 2 or 3 times.
Shunt removal is associated in one big series with the best outcome(PubMed).
Relevant links to my Medscape blog