Gary Lum glum at ozemail.com.au
Mon Jul 20 07:36:30 EST 1998

Andy wrote:

> However, what I need to know is that when a patient has a bacterial
> meningitis, what level of bacteria would one expect to find!

It often depends on the organism causing the infection.  Most folk who
have lots of laboratory experience will be able to share stories of
pneumococcal meningitis where the counting chamber has been replete with
pneumococci despite having few polymorphs, in other circumstances, the
reverse can be true.

> I remember looking at CSF and sometimes one could see on a wet prep bacteria!
> So the number can be significant! However, that may just be some cases.
> Are there bacterial meningitis cases where bacteria would be virtually
> undetectable by microscopy?

A lot depends on the microscopy and the person performing the Gram's
stain etc.

First of all, methanol fixation is often said to be better than flmaing
because of potential disruption of cells.  Then I would always prefer a
cytospin over a standard layered Gram's stain.  In addition, if Acridine
Orange is used the sensitivity of microscopy is enhanced.

We have done away with Bacterial Antigen Detection (BAD) testing because
we have found a Gram's stain has been a better predictor, but then we do

There are a reasonable number of times when we see nothing in the Gram's
stain but culture a bacterium consistent with ABM.  I suspect other
laboratory folk have similar experiences.



Dr Gary Lum
Director of Microbiology and Pathology
Royal Darwin Hospital

Microbiologists do it with culture and sensitivity
mailto:glum at ozemail.com.au

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