DIAGNOSIS 



1853 



of the rectum. Cancer of the colon and intussusception may also cause the 

 passage of blood, with or without mucus and with or without tenesmus, but 

 the history and a careful abdominal examination, together with the discovery 

 of a localized swelling, should serve to distinguish these affections. Para- 

 metritis on the left side may cause diarrhoea, and more rarely the passage of 

 blood and mucus, but the absence of tenesmus, the presence of pain more at 

 the side of the uterus than in the sigmoid colon, should indicate the necessity 

 of an examination per vaginam or per rectum, when the nature of the case will 

 be cleared up. A careful examination of the faeces should exclude such causes 

 as fish-bones injuring the rectum. Mercurial poisoning can be distinguished 

 by the history, the presence of salivation, etc. The diagnosis from amoebic, 

 balantidic, and the other dysenteries of animal origin can only be made by 

 the careful microscopical examination of the faeces, when the absence of these 

 parasites will be made certain. The absence in dysenteric stools of Charcot- 

 Leyden crystals and presence of very abundant cellular exudate with 

 macrophages and preponderance of polymorphonuclears points to the con- 

 dition being bacterial rather than amoebic. 



Positive diagnosis can, however, only be made by a bacterio- 

 logical examination of the faeces and the determination of the 

 specific bacillus. Agglutination tests with the patient's blood are 

 not of much use in acute cases, as agglutinins are not present in the 

 blood the first few days of the disease. 



For the bacteriological diagnosis a shred of mucus or pus is smeared over 

 a plate of MacConkie's bile — salt-lactose-neutral-red agar, by means of a bent 

 glass rod or Kruse's platinum pencil. 



Two more plates of the same medium are prepared in a similar manner 

 without recharging the rod or pencil. 



Any white colonies which develop are further investigated as to their sugar 

 reactions, and by using the agglutination and absorption methods. 



The following method will be found useful: — Twenty white colonies are 

 selected; in this way we discard all lactose rapid fermenters. From each 

 colony one glucose peptone water (or glucose agar) and a litmus milk are 

 inoculated. After sixteen to twenty-four hours at 35° C. to 37° C. the glucose and 

 milk tubes so inoculated are examined: all the strains which have produced 

 gas or clotted milk are discarded. In this way we discard all germs of the 

 genus Salmonella, Lankoides (p. 938), etc., and we retain only the strains 

 which do not produce gas in glucose and do not clot milk. If a germ does 

 not produce gas in glucose, as a rule it does not produce it in any other carbo- 

 hydrate, and therefore we may say that we are left with strains which do not 

 produce gas in any sugar and do not rapidly clot milk, and which, therefore, 

 if they are bacilli, must belong to one of the following groups: — [a) Eberthus 

 (p. 930), (&) Alcaligenes (p. 930), (c) Vibriothrix (p. 1068), {d) dysentery- 

 metalkaligenes group senstc lafo. From the glucose tubes hanging-drops are 

 made ; all germs which are not bacilli are discarded, and similarly all motile 

 germs. In this way we shall retain only germs which are non-motile bacilli, 

 which do not produce gas in any sugar, and do not clot milk — bacilli, 

 therefore, which belong to the dysentery (glucose acid) and metalkaligenes 

 group (glucose .not acid). Those which ferment glucose (acidity only) are 

 further investigated, and agglutination reactions are carried out, using 

 Shiga, Flexner, and other dysenteric sera. 



At times it will be found of advantage to use the so-called Castellani's 

 contemporary gas-agglutination test. Tubes of glucose peptone water with 

 Durham's fermentation small tubes are prepared, and two or three drops of a 

 mixed serum, Shiga-Flexner, Hiss, etc., added. Twenty white colonies are 

 inoculated in twenty such tubes. If any of these tubes, after twelve hours 

 in the incubator, shows absence of gas and presence of agglutination, a diagnosis 

 of bacterial dysentery can be made, though not of what variety of bacterial 

 dysentery. It must be remembered also that there are rare strains of dysen- 

 teric bacilli which are not agglutinated by any of the usual antidysentery sera. 



