CHOLERA VIBRIO 571 
vaccine is combined sometimes with typhoid, ])aratyphoi(l alpha and 
paratyphoid beta, makinji: a so-called T.A.B.(\ vaccine. It was used 
on the eastern front durinji; the World War, and is said to have been 
effective. KoUe and Kraus^ have prepared sera which are said to 
possess some preventi\'e and curative \alue: the evidence is as yet too 
meaner to warrant definite conclusions concerning the value of these 
sera howexer. 
Bacteriological Diagnosis.— Isolation and identification of the cholera 
vibrio. 
1. Microscopic. --The feces may be examined directly for cholera 
vibrios. Large numbers of slightly curved or S-shaped actively motile 
vibrios, which when stained with dilute carbol-fuchsin exhibit slightly 
tapered ends, are very suggestive. A bit of mucus (a "grain of rice" 
from a rice-water stool) is particularly good for microscopic exam- 
ination. The organisms frequently exhibit a marked parallelism of 
their long axes, resembling a school of fish in their arrangement if 
the material is not roughly handled during the preparation of the 
smear. 
2. Culture. — {a) Schottelius' method. The principle involved: 
The cholera vibrio grows particularly well in alkaline peptone solu- 
tion (Dunham solution). B. coli and other intestinal organisms grow- 
less readily. 
Tcchnic.—A loopful of feces,- or preferably a small piece of mucus 
is emulsified in a tube of Dunham's peptone solution and incubated 
at 37° C. for six to eight hours. The cholera organisms are very 
aerobic and actively motile, and collect in large numbers at the sur- 
face of the medium, therefore two or three loopfuls of material from 
the surface of the Dunham tube are inoculated into a second tube 
and the process repeated in a third tube, when a nearly pure culture 
of cholera vibrios will frequently be obtained. The organisms may be 
plated directly from the enriched growth in the first, second, or, best, 
from the third tube, and the pure cultures agglutinated with a high 
potency specific anticholera serum in dilutions from 1 to 500 to 1 to 
5000.^ The nitroso-indol test should be made on each of the three 
Dunham tubes after removal of the organisms, for a positive nitroso- 
indol reaction, while not diagnostic, is very suggestive. 
(b) A small amount of feces or a flake of mucus is emulsified in 
1 Wien. klin. Wchnschr., 1909, 22, 1397. 
2 If the pieliminary microscopic examination fails to reveal a preponderance of 
vibrios of characteristic morphology, a larger amount of fecal material must be taken. 
Several grams of feces emulsified in 100 to 500 cc. Dunham solution may give positive 
results in exceptional cases when smaller samples are negative. 
' The anticholera serum is best obtained from rabbits which have been immunized 
by repeated injections of known cholera vibrios. The titer of the serum should be at 
least 1 to 4000. A final diagnosis should be made preferably only when the suspected 
organism agglutinates in a dilution of at least 1 to 2000, although clumping of freshly 
isolated vibrios at a dilution of 1 to 500 is fairly conclusive. The sera of horses and 
other large animals are less suitable for agglutination with cholera vibrios; natural 
antibodies occur which cause clumping in relatively high dilutions. 
