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.

    24/144 (page 12)
    a used a mixture of bile, peptone, and glycerine, but in this series simple sterile bile was employed, as at the beginning of the investigation it had already been established that this constituted a satisfactory: medium. For a short period a solution of glycocholate of sodium ‘was employed, but this had the disadvantage that if too much blood were added clotting occurred. The hospitals were supplied with long test-tubes containing 10 c¢.c. of sterile ox-bile. Into these were injected 2 to 5 c.c. of the patient’s blood, and the tubes sent to the laboratory. A tube on arrival was placed in the incubator and left for forty-eight hours. It was then shaken and a large loopful spread on an Endo-agar plate ; the plate was examined after incubation for twenty- four hours. During a part of the time the original culture was left in the incubator for seventy-two hours and plated on the third day, but a series of specimens which were examined after two, and again after three days showed that the longer period had no advantage over the shorter. Feces. No attempt was made to obtain the administration of drugs with a view to rendering the stools fluid, although it is possible that this would have tended to increase the probability of finding the offending organism. The material was sent to the laboratory in corked test-tubes. On receipt, if the stool was not already fluid, a thick suspension in bouillon was made and a large loopful spread on each of two plates of Endo’s medium. Many varieties of medium have been advocated from time to time for the differential cultivation of the bacilli of the coli-typhoid group, but the reduced-fuchsin medium of Endo has been in use in the Public Health Laboratories for some years and has been found, if prepared with care and used only when in good condition, to give satisfactory results.) The typhoid and paratyphoid bacilli grow well on it, and although their colonies may — by simulated in appearance by other of the non-lactose-fermenting coliform bacilli, this difficulty . is inevitable, whatever variety of medium be used. The plates were incubated for twenty-four hours and at the end.of this time, if suspicious colonies were present, several of these were sub- cultured, again on Endo’s medium and in such a way that after a further period of twenty-four hours a single colony could be obtained from each subculture. Thus every culture to be examined - in detail was obtained from a single colony from a culture which had itself originated from a single colony ; to subculture from a single colony on the original plate is by no means a guarantee of. purity. . eo Urine. The specimens of urine examined had been obtained in the ordinary way, without special precautions other than the thorough cleansing of the vessel used. The specimens were not cen- trifuged, but two or three drops of each were spread on a plate of Endo’s medium. The specimen was itself incubated for twenty-four hours and a drop again spread on a plate. Suspicious colonies from either plate were purified by subculture and examined. . Identification of the Suspicious Colonies. Suspicious colonies, as mentioned above, were always purified by two subcultures before proceeding to identification. The exact procedure then followed was not the same throughout the series. For the greater part of the time the method adopted was to inoculate from the second subculture a bouillon-tube and a glucose-bouillon-tube, the latter containing litmus and having (‘) The Endo medium was prepared in the usual way, except that the reduction of the fuchsin was effected by a special preparation of sodium sulphite, viz. that supplied for photographic purposes by Lumiére et Jougla, Paris. It has been found that with this preparation the reduction is more satisfactory than with ordinary commercial sulphite of sodium. = t