THE BACTERIOLOGICAL EXAMINATION OF THE BLOOD I59 



A word of warning is necessary in the interpretation of results 

 which indicate that staphylococci are present in the blood. These 

 organisms are constantly present in the skin, and maybe found in 

 cultures, unless rigid antiseptic precautions are taken. Strepto- 

 cocci may also occur as contaminations of cultures, but compara- 

 tively rarely. 



3. Anthrax Bacilli. — These may be detected with ease and 

 certainty, but they are probably never found in the blood until it 

 is too late to skve the patient. 



4. Ttibercle Bacilli. — These are only present in very scanty 

 numbers, and are very difficult to detect. The diagnosis of 

 miliary tuberculosis is to be made by other methods, chiefly by 

 that of exclusion. 



5. The pneumococcus is found in severe cases of pneumonia 

 (probably it might be found in most cases if a sufficiently large 

 quantity of blood were examined) and in septicaemia and ulcerative 

 endocarditis when due to this organism. When found in the blood 

 by ordinary methods it always indicates a bad prognosis, and sug- 

 gests the use of vaccine. 



6. Typhoid bacilli. (See p. 74.) 



7. The bacillus of glanders may be found in acute cases of that 

 disease, but its isolation and identification are matters for an 

 expert. 



8. The influenza bacillus is present in some or, according to some 

 authorities, all cases of influenza. It may be searched for in films, 

 but no importance should be attached to a negative result. 

 Cultures have been obtained in some cases of ulcerative endo- 

 carditis. 



9. The Bacillus of Plague. — This organism is often present in the 

 blood in relatively large numbers, and the disease can usually 

 be diagnosed after a careful search through a number of suitably 

 stained films. But the investigation of a drop of fluid drawn 

 from the bubo (if one is present) permits of an easier and earlier 

 diagnosis. The blood examination is of most value in the pul- 

 monary and septicaemic forms of plague. 



10. The spirillum of relapsing fever is easily found, for' it possesses 

 well-marked characters and is present in great numbers. The 

 diagnosis of relapsing fever cannot be made until it has been 

 demonstrated (see Fig. 29). It is best seen by mounting a 

 small drop of blood between slide and cover-glass, and ex- 

 amining it in a perfectly fresh state, when the spirilla are easily 



