Memorandum on typhoid fever.

Date:
1939
Catalogue details

Licence: Public Domain Mark

Credit: Memorandum on typhoid fever. Source: Wellcome Collection.

    8/10 (page 8)
    obviously much more convenient than the subcutaneous method, confers uncertain protection and therefore it seems generally to be justified only when the orthodox method cannot be applied. Ministry of Health, London, S.W.I. November, 1939. APPENDIX. LABORATORY DIAGNOSIS. Culture and identification of the specific bacterium in the blood or excreta is the only method of diagnosis not open to doubt. Both are practicable, moreover, in the earliest stage of the symptoms and should be the first laboratory tests to be applied. Of importance, later, though less absolute in diagnostic accuracy, is the Widal test which depends on the development of specific agglutinin for the typhoid bacillus in the blood of the infected person; positive Widals may be obtained towards the end of the first week of illness but are rare and weak before that. The following technical hints may be of service in the collection of specimens and their examination in the laboratory. (1) Blood culture.—Blood should be drawn from a vein (with the usual aseptic precautions) as soon as the suspicion of typhoid fever arises. A convenient tool for the purpose is the Behring Venule but an ordinary to ml. all-glass syringe (dry, sterile) or a hypodermic needle (gauge S.W.G.19) attached to a piece of rubber tubing may be used. Which- ever is employed, either an anticoagulant (citrate, oxalate, or liquoid) or fresh sterile ox-bile should be present in the recipient. McCartney bottles (with rubber diaphragm in the cap) are convenient when syringes are used. Plain screw-cap bottles can be employed for receiving blood from a piece of rubber tubing, though the necessity of removing the cap to insert it introduces the risk of contamination. On arrival at the laboratory the blood is either incubated forthwith, if it is already mixed with sufficient bile, or is pipetted off aseptically into bile-broth (preferable) or ordinary nutrient broth in the proportion of 10 of medium to 1 of blood and then incubated. Subcultures from it on plates of MacConkey or other suitable medium should be done daily for at least 5 days before a negative result is recorded. A positive result is obtained when colonies of B. typhosus (identified as described below) have made their appearance. Should the blood specimen received at the laboratory be ordinary clotted blood, the serum should be pipetted off and the clot, broken up with a sterile glass rod, transferred to nuirient medium in similar fashion. The quantity of blood suggested (10 ml.) is preferable to less amounts but quite smal! quantities may give a positive culture and are better than none. (2) Culture from faeces. (a) Specimens.—Freshly voided material should be taken, about half a teaspoonful being transferred to the outfit-tube provided. If delay of more than 18 hours is likely before the specimen can reach the laboratory, the faecal specimen should be put in sterile glycerine-saline (30 per cent. neutral glycerine in 0-6 per cent. saline) for transit. Should a fresh specimen not be available at the time of visit to the patient, a rectal swab may be taken instead; an ordinary throat swab may be used for this purpose.