4. Diphtheria. Specimens for diphtheria should be 
collected from both the nose and throat. Two 
sterile swabs should be used for each person 
cultured, one swab to obtain a specimen from 
the throat lesions or tonsillar crypts and the 
other to collect materials from the nasopharynx. 
Swabs should be kept separate during transport 
to the laboratory. 
Specimens for isolation of the agent 
To obtain nasal and throat specimens, the swab 
should be introduced into the nares at a right 
angle to the plane of the face, inserted com- 
pletely into the nasopharynx, and rotated over 
the pharyngeal surface near or in the tonsillar 
fossa. Because a nasal membrane is a particu- 
larly good source of organisms, the swab should 
be placed at the margin of the membrane, if 
present, and the specimen taken without exces- 
sive bleeding. 
Preferably, the initial isolation of organisms 
suspected of being Corynebacterium diphtheriae 
should be carried out in a competent laboratory 
near the source of the specimens. If it will re- 
quire more than two hours to get the specimens 
to the laboratory, they should be inoculated to 
Loeffler’s slants and incubated overnight before 
transporting them. The nasopharyngeal and 
throat swabs should be rotated gently over the 
surface of separate slants of the medium. Care 
should be taken not to break the surface of the 
medium. The swab should then be placed in a 
separate tube to be sent to the laboratory with 
the slant. 
On arrival in the laboratory the inital swab is 
inoculated to a Loeffler’s slant, a tellurite agar 
plate, and a blood agar plate. If the specimen 
is received on Loeffler’s medium, a smear is 
made for microscopic examination, and a rep- 
resentative sample of the growth is inoculated 
to tellurite and blood agar plates. The use of 
blood agar is necessary to demonstrate the pres- 
ence of Group A streptococci, or strains of C. 
diphtheriae which may be inhibited on the tel- 
lurite medium. 
In carrier surveys, both swabs may be streaked 
gently and repeatedly over the surface of a single 
slant. Be sure to rotate the swabs between the 
thumb and forefinger as the swabs are drawn 
back and forth over the medium. Streaking of 
tellurite plates with the initial swabs taken in 
carrier surveys is of little advantage. On occa- 
sion, inhibitory lots of Loeffler’s medium have 
been encountered due to the presence of anti- 
biotics in the serum from which the medium 
was prepared. Precaution should be taken, 
therefore, to make sure that all lots of the 
medium to be used will support growth of C. 
diphtheriae. Diagnosis from smears made 
directly from the patient should never be at- 
tempted since many other organisms morpho- 
logically resembling C. diphtheriae occur in the 
normal or diseased throat. 
5. Enteric Infections. In suspected cases of ty- 
phoid fever and salmonellosis, specimens sub- 
mitted for culture include blood, feces, and 
urine. Rectal swabs may be obtained by using 
an ordinary cotton-tipped applicator. Blood 
serum for agglutination tests is not recom- 
mended because such tests provide little or no 
significant information. Blood cultures and ser- 
ologic tests are not done in shigellosis. The mul- 
tiplicity of fluids suggested as transport media 
for specimens to be cultured indicates that none 
is ideal nor markedly superior to others, and, 
therefore, isolation of the agent should be at- 
tempted in the nearest competent laboratory. 
a. Typhoid fever 
Specimens to be collected for isolation of 
Salmonella typhi 
( 1 ) Blood taken early in the course of ill- 
ness is the specimen of choice, but the 
probability of recovery of the organism 
decreases rapidly after 7 to 10 days of 
illness. Ten to 15 ml. of blood 
should be drawn directly into a “B-D” 
blood culture medium bottle (the vol- 
ume of broth should be at least 10 
times the volume of blood) and should 
be examined for growth after 3, 5, 7, 
and 14 days’ incubation. If the blood is 
not drawn directly into the culture 
medium, an anticoagulant should be 
added. 
(2) Stool examination is accomplished by 
adding approximately two grams, or a 
portion the size of a small marble, of 
formed stool to one ounce of Sachs 
30% glycerol in buffered physiological- 
saline in a two-ounce, screw-cap bottle 
or “alkaselzer” bottle. Shake the bottle 
vigorously to emulsify the specimen 
before shipment. If the stool is liquid, 
add 2 ml. of the specimen to the pre- 
servative in the bottle. Be sure to in- 
clude in the specimen any bits of 
mucosa or mucus present in the stool. 
8 
