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59
serum from the swab and the culture examined after
incubation for 10 to 24 hours at a temperature of 37 degrees
centigrade. Examination of the culture is the only certain
method of making the diagnosis of Diphtheria in slight or
doubtful cases. The medium used has the following
composition and is made in the laboratory : —
Loeffler's medium.
Blood-serum (calf), 3 parts.
Glucose peptone broth, 1 part.
Films made either from the swab directly, or else from
the culture, are stained with Loeffler's methylene blue or
Pugh's stain, and any organisms showing the characters of
Diphtheria bacilli are then stained by Neisser's method.
The presence of definite granules when stained by the latter
method is taken generally as indicating the presence of
Diphtheria bacilli. In cases of doubt sub-cultures are made
and further tests applied.
Sterilised swabs enclosed in a box and addressed
envelope suitable for transmission through the post are
supplied to medical practitioners on application.
There can be no doubt that owing to the facilities
afforded by free bacteriological diagnosis, numerous slight
cases of Diphtheria are recognised which might otherwise
be missed. In this way the spread of Diphtheria is checked.
Furthermore, bacteriological examination of the throat
affords a safe method of ascertaining whether a child is free
from infection after convalescence. In certain cases
Diphtheria organisms may remain in the throat or nose for
a long time after the child is apparently well. The result
of allowing the child to mix with other children may be
the conveyance of the disease to them. As a rule two
successive negative swabs should be obtained before a child
is considered free from infection. This is the method