I personally have never heard of this methodology. I looked it up in
Google, and it seems to be a methodology for different tests, not a test
in and of itself.

When a lumbar puncture is ordered to rule out meningitis, there are
usually 3-4 tubes of CSF drawn off in special lumbar puncture tubes
labelled 1,2,3,4. All tests on CSF's are considered STAT tests and the
basic tests are done right away. Every lab has its own protocol as to
which tube goes where. One tube goes to microbiology; one to Hematology,
and the other goes to chemistry. If there is a fourth tube it is usually
saved for possible further testing in microbiology. All of them go to
microbiology first at our place, since we have to have a sterile
specimen. We then distribute the other tubes to the other departments.

Micro does a cytocentrifuge smear of the fluid and performs a gram stain
on this slide. If the gram stain is positive for any bacterial
morphologies (gram positive cocci in pairs, gram negative rods, gram
negative diplococci, etc.) the floor is called immediately as this is
considered a life threatening situation. Bacterial meningococcal
meningitis presents with a gram stain of many WBC's and gram negative
intracellular diplococci. This infection can kill within hours. CSF's
that are cloudy are almost always positive.

We used to perform an antigen tests that included Ag for Group B strep,
N. meningitidis, H. influenzae, a certain strain of E. coli, and S.
pneumoniae. We stopped doing it a year ago, as a cytocentrifuged gram
smear is more sensitive than the test was. The doctors really never
complained that we stopped performing it. It was a pain in the rear,
also. It was a latex agglutination test.

We then spin the rest of the fluid in our tube and plate the sediment
onto blood agar and chocolate agar. We hold the plates three days and
look for any growth each day before calling it negative and signing it
out. We give updated preliminary reports each day. If fungal or
mycobacterial infection is suspected, additional media are added for
these organisms. Fungal media is held for four weeks and mycobacterial
media (acid fast organisms, the most common of which is M. tuberculosis)
is held for 6 weeks. Micro can also test for viruses, and enterovirus
PCR seems to be a popular order. We also get seasonal requests for West
Nile Virus. The most common fungal infection of CSF is Cryptococcus
neoformans.

Hematology gets an aliquot and performs a cell count. I believe a
differential smear is done on a cytocentrifuged smear if the white count
is over a certain level. A differential smear is stained with Wright's
stain and the cells are enumerated - how many segmented neutrophils,
lymphocytes, monocytes, etc. are seen.

The most common tests that chemistry performs on CSF are glucose and
protein, but other tests can be performed also, depending on the
diagnosis. Sometimes spinal taps are performed to rule out multiple
sclerosis, and then a different battery of tests is added on to the ones
above.

The textbook picture of a bacterially infected CSF would include an
elevated total protein, a low glucose, an elevated WBC count, and a
positive gram smear.

Where did you come up with this ELISPOT test having to do with
meningococcemia? Can you post a URL? Every lab I've ever worked in for
over thirty years performs the testing above as a routine starting point
for lumbar punctures.

Anyone else care to chime in?

Judy Dilworth, M.T. (ASCP)
Microbiology