Reports and notes of the Public Health Laboratories, Cairo. No. 1, 1917.

Date:
1918
Catalogue details

Licence: In copyright

Credit: Reports and notes of the Public Health Laboratories, Cairo. No. 1, 1917. Source: Wellcome Collection.

    32/144 (page 20)
    okies IV.—THE CHARACTERS OF THE TYPHOID AND PARATYPHOID BACILLI OBTAINED. As already stated, the identification of the organisms as typhoid or paratyphoid bacilli was made by the examination of the subcultures of suspicious colonies as to their agglutination by the three specific sera. Each organism in the series, therefore, may be taken as having shown definite agglutination with the corresponding serum, and the test was found to be very satisfactory and to give rise to no ambiguity in the interpretation of the results. The tests other than agglutination which are chiefly employed at the present time for the differentiation of the members of coli-typhoid group are the so-called biological reactions, a term employed to indicate the action of the organism im question on certain chemical substances, espe- cially carbohydrates, and on milk. The majority of the strains isolated have been examined with regard to their action on milk and on the five carbohydrates recommended by McConkey as most suitable for routine use, viz. lactose, saccharose, dulcite, mannite, and glucose. The results are recorded below. BaciLttus TyPHosus. Action on Carbohydrates. The typical reaction of the typhoid bacillus is that it should produce no change in lactose, saccharose, and dulcite, and form acid but no gas in mannite and glucose. Of thirty strains examined, twenty-nine gave this typical reaction, although in one case the amount of acid formed from mannite was very small. In the case of one strain, a bacillus isolated from the urine, no acid was formed from mannite after five days; the strain was agglutinated by a typhoid serum at a dilution of 1 in 1,600. Action on Malk. Thirteen strains were examined as to their action on litmus-milk. All gave rise to a definitely acid reaction within the first twenty-four hours, and this persisted for over a week in every case. At the end of the second week, with a certain number of the strains the medium had lost its- acidity, and by the end of the third week a diminution in acidity had occurred in every case; five strains showed a reduced acidity, six had returned to the original colour of the medium, and two, had become definitely alkaline. No clotting occurred. : Bacittitus Paratypuosus A. Action on Carbohydrates. The typical reaction of the paratyphoid bacilli, which they share with Gaertner’s bacillus and other members of this group, is that they should produce no change in lactose and saccharose and form acid and gas in dulcite, mannite, and glucose. The strains of b. paratyphosus A isolated proved to be very erratic in their action and to present in this respect a striking contrast to the strains of b. typhosus and of b. paratyphosus B. While conforming to type in their action on lactose and saccharose (although it must be admitted that a definitely lactose-fermenting organism would have therefrom escaped recognition), they presented a considerable amount of variety in their action on dulcite, mannite, and glucose. The results, which indicate the condition observed - after five days, are set out in Table X. It will be noticed that of 303 strains examined, 238 gave the typical reaction to some degree, although only ninety-four produced a sufficient quantity of acid and gas for the reaction to be considered wholly typical. The two strains giving acid only in mannite and glucose, the typical reaction of b. typhosus, were agglutinated by a paratyphoid A serum at a dilution of 1 in 500 and were not agglutinated by a typhoid serum.