The Suction Culture Method for the Isolation of Dysentery Bacilli from the Mucus of Dysentery Patients and Carriers

Abstract

A suction culture method for the isolation of dysentery bacilli from the mucus of dysentery patients and carriers was devised by the authors. The mucus on the rectal ulcer or in the rectal cavity was aspired at the rectoscopical examination of dysentery patients and carriers, with a small pipette (5mm×35cm) equipped with a rubber cap and then cultured on SS agar.
The results obtained with this method were compared with those obtained with swab culture or fecal culture for the isolation of dysentery bacilli in 785 cases, including dysentery patients and reconvalescent and healthy carriers. Coincident results were obtained in 80.3% of 579 cases, in which the suction culture method was compared with swab culture method simultaneously. In 15.0% of the cases dysentery bacilli were isolated only with the suction culture method, while in the remaining 4.7% only the swab culture gave positive results. Of the 206 cases, in which the suction culture method was compared with the fecal culture method, 89.7% delivered coincident results. In 8.7% the suction method alone, and in 1.5% the fecal culture method alone, gave positive results.
It would be noteworthy that dysentery bacilli were more easily demonstrated with the suction culture method than with other methods in cases of reconvalescent patients and healthy carriers, in whom the amount of excreted bacilli was so small, that their isolation was difficult with the usual methods. The suction culture methods was therefore considered to be superior to the ordinary methods in the detection of bacillus discharge after treatment or in carrier state.
The suction culture of mucus was performed once a week, and the results were compared with those obtained with daily cultures of feces or swabs for a week. In 88.3% of the examined cases the results with the both methods were in agreement. In 7.2% positive results were obtained only with the suction culture method. The sum of the above-mentioned percentages, 95%, was regarded by the authors to represent the reliability of the suction culture method carried out once a week, in comparison with the results by daily cultures from feces or swabs for a week. This indicated that the ordinary daily examination of feces and swabs for a week could be replaced by the suction culture method once a week, without a significant reduction in the percentage of isolation 8f dysentery bacilli. If a rectoscopic examination was available, this method was recommended for the judgement whether dysentery bacilli continued to be discharged or not.
Not only the examination of feces, but aho that of rectal mucus should be taken into consideration in the diagnosis, immunology, epidemiology and therapy of dysentery.