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.

    26/144 (page 14)
    been carried out to the same extent as the negative cases, the various other factors which limited the degree of examination affecting the positive and negative cases equally, the percentage of positive cases in groups I and III would have been higher and those of groups V and VII lower than that actually found in each case. ‘Groups II and IV were largely composed of convalescents examined to determine their freedom from bacilli before transference. As already indicated, the cases termed positive were those from which b. typhosus, b. para- typhosus A, or b. paratyphosus B was obtained. The relative proportion in which these three organisms were found was :— Typhoid \:2/ 24st meee. cheta0 c=) epeneont: Paratyphoid:A. guaderhsssuiiticehiace (2099501 % Paratyphoid Bi hice ee! nee tee eg * Five cases of double infection were found, which have not been included in the figures, wz. :— One case giving b. paratyphosus A from the blood and b. typhosus from the feeces. Two cases giving b. paratyphosus A from the blood and b. typhosus from the urine. Two cases giving b. paratyphosus A and B from the urine. If the first three cases are included as cases of typhoid, they do not affect the percentage of cases of typhoid as represented by the nearest whole number. 11l.—A CONSIDERATION OF SUCH CONCLUSIONS AS MAY BE DRAWN AS TO THE VALUE IN DIAGNOSIS OF THE BACTERIOLOGICAL EXAMINATION OF CASES CLINICALLY ENTERICA. Although the simplest and, under certain circumstances, the only practicable method of arriving at a diagnosis in a case suspected of enterica is that of the agglutination reaction, under certain conditions a bacteriological examination may be necessary. For example, the diagnosis may be required in the first week of the illness, when the agglutination reaction is not to be relied on, or the reaction may be indefinite or fail altogether in a case in which the clinical and other conditions point definitely to an enteric infection, or the agglutination reaction may be complicated and. perhaps rendered useless by a recent inoculation, or again the question may not be one of simple diagnosis but of the continuance of infectivity in a convalescent or the presence of bacilli in a carrier. Under any of these circumstances it becomes necessary to look for the offending bacilli in order . - to arrive at a definite conclusion, and if the bacillus be found this conclusion is attained, but on the other hand, if the bacillus be not found, no definite conclusion is attained. While a positive result is, other than under exceptional conditions, conclusive, a negative result is regarded as having practically no significance, although a negative conclusion may be regarded as becoming more and more justifiable as the number of negative results increases. Now, all diagnosis, clinical, bacteriological or otherwise, resolves itself ultimately into a question of probability, although it is not often possible to express it as such in definite terms. It has, therefore, appeared worth while to employ the considerable number of examinations involved in this investigation in an effort to throw some light on the question of the degree of probability of arriving at a positive conclusion from the bacteriological investigation of a case of enterica. The results of the inves- tigation of the blood, urine, and faeces have been considered separately. Blood-Cultures. The number of cases examined by blood-culture was 1,188, and of these the blood-culture was positive in 226, or 19 per cent. The period of the illness at the time the blood-culture is made has been stated to be an important factor in the probability of obtaining a positive result. In a certain number of cases in this series