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requisite to identify it. He gives some—and the most important—of its distinguishing
characteristics :—
1. Morphologically, it is a coccus, usually a diplococcus.
2. As to situation, it is chiefly intracellular, but this is not constant.
3. As regards stains, it is discoloured by Gram's method.
4. As regards cultural characters, Optimum development of the meningococcus occurs
at 36°—37° C., and at 42° C. growth is arrested. "A character of first-rate importance
from the differential point of view is the fact that the meningococcus will not grow at a
temperature below 25° C."
There are other distinguishing characteristics, viz., its vitality, pathogenesis, agglutination and
fermentation. But apart from these, if the micro-organisms does not fulfil tests 3 and 4 it cannot
be considered to be the meningococcus ; for it may be one of the numerous other closely similar cocci.
From Dr. Mervyn Gordon's description it will be seen how highly technical a proceeding is
the identification of the distinguishing mark of cerebrospinal fever, and what a degree of skill and
experience is necessary for the recovery of the true organism. With the view of ascertaining
how far the methods recommended by him were carried out in the identification of cases certified
during 1908, inquiry was made of several of the institutions from which notifications were received,
as to the nature of the bacteriological inquiry commonly there in use for the identification of the
meningococcus. These are set out below as follows, viz., Nos. A, B, C, D, E, F.
A.
1. The organism a diplococcus.
2. Intra- and extra-cellular.
3. Gram-negative.
4. Growth on ascitic agar at 37° C.
5. No growth on ascitic agar at 22° C.
6. Naked eye appearance of colonies taken into
account.
7. With sugar media + ascitic fluid, meningococcus
acidifies maltose, glucose, galactose, laevulose,
not cane sugar, not lactose.
The sugar test often not done, but considered to
be of value. In cases of difficulty of diagnosis, the
clinical features of the case are taken into consideration.
B.
1. The organism a diplococcus.
2. Intra- mainly, may also be extra-cellular.
3. Gram-negative.
4. Grows on nasgar at 37° C.
5. Does not grow in broth—little in milk.
6. Naked eye appearances of colonies taken into
account.
7. The non-growth at 22° C. not considered to be
a necessary test.
8. The sugar test considered to be valueless.
Considered possible to diagnose cerebrospinal fever
on bacteriological examination alone.
C.
1. The organism a diplococcus.
2. Intra- or extra-cellular.
3. Gram-negative.
4. Growth on nasgar at 37° C.
5. No growth on nasgar at 22° C.
6. Naked eye appearance of colonies taken into
account.
The above points are taken into consideration in
pronouncing on the presence or absence of the
meningococcus. But Nos. 1, 2 and 3 would be considered
sufficient, having regard to the clinical and
other features of the case.
D.
1. The organism a diplococcus.
2. Intra- or extra-cellular.
3. Gram-negative.
4. Growth at 37° on agar smeared with rabbit's
blood.
No further culture tests applied. Cases of meningitis
returned as meningococcal on evidence furnished
by above tests only.
E.
1. The organism a diplococcus.
2. Intra- or extra-cellular.
3. Gram-negative.
No further bacteriological tests are applied. Evidence
furnished only by these tests warrants meningitis
being returned as meningococcal.
F.
1. The organism a diplococcus.
2. Intra- or extra-cellular.
3. Gram-negative.
The examination of the organism is not carried
beyond this point; no cultural test is applied ;
in evidence furnished by these tests meningitis
may be returned as meningococcal.
It is evident that cases regarded by methods E and F as cerebrospinal fever, may be rejected
by methods A and B. Yet all are recorded as genuine cases of the disease. A stronger illustration
could scarcely be adduced for the necessity of a common standard of classification for cases of this
disease.
W. McC. Wanklyn.