DIAGNOSIS OF MIXED INFECTIONS 



1397 



patient has been residing, and this can be confirmed by the isola- 

 tion of the specific bacilH from the blood. 



Par enteric Fevers. — These can only be diagnosed by the bacterio- 

 logical examination of the blood and faeces. 



Ulcerative Endocarditis. — Usually in this complaint there are 

 recurring chills, irregular fever, substernal pains, and endocardial 

 murmurs, while bacteriological examination of the blood may not 

 merely differentiate it from enteric fever, but may indicate the 

 germ which is causing the endocarditis. 



Pyc&mia. — In the first week this may be difficult, and depend 

 upon the bacteriological examination, but the usually intermittent 

 fever, the prostration, and the sweats, may give rise to suspicion. 

 The marked leucocytosis may also arouse suspicion. 



Weil's Disease. — This may be recognized by the early onset of 

 jaundice. 



Diagnosis of Mixed Infections. — As already stated, mixed infec- 

 tions, especially typhoid and malaria, typhoid and paratyphoid, 

 typhoid or paratyphoid and coli-like germs, are not rare. In the 

 typho-malarial-infection cases the microscopical examination of 

 the blood will reveal Laveran's parasites. As regards the diagnosis 

 of the second group of mixed infections — viz., typhoid + para- 

 typhoid, or typhoid + coli infections — the diagnosis is based on : — 



1. Haemocultures. 



2. Castellani's absorption test. 



The technique for haemocultures has already been given. We may 

 here remind our readers that the finding in the blood of some other 

 organism besides the B. typhosus does not mean always that the Case 

 is a real mixed infection. The organism found may play only a 

 saprophytic role, especially if the blood does not contain specific 

 agglutinins for the germ. 



Castellani's A hsovption Test. — The usual agglutination tests are not , 

 as a rule, sufficient to make a diagnosis of mixed infection, because 

 coagglutination does not always mean multiple infection. If the 

 blood of a typhoid patient agglutinates the B. paratyphosus, besides 

 the B. typhosus, one is not justified in coming to the diagnosis of 

 a mixed infection brought about by the B. typhosus and the 

 B. paratyphosus B, because it is well known that the blood of a 

 typhoid patient may contain, besides the specific, primary or homo- 

 logous agglutinins for the typhoid bacillus, secondary or non- 

 specific or heterologous agglutinins for 5. paratyphosus B and many 

 other bacilli, such as many strains of coli. This has been demon- 

 strated by many authors. Griiber and Durham, as long ago as 

 1896, demonstrated that the typhoid sera may agglutinate Gaertner 

 bacilli. Zupnik and Poser later found out that 89 per cent, of 

 typhoid sera reacted with paratyphoid B, and 40 per cent, with 

 paratyphoid A. 



Boycott, who has made a very complete investigation of the 

 subject, has noted that 59 per cent, of typhoid sera present co- 



