216 INFLAMMATION AND SUPPURATION 



Although many of the lesions produced by the bacteria 

 under consideration have already been mentioned, certain con- 

 ditions may be selected for further consideration on account of 

 their clinical importance or bacteriological interest. 



Endocarditis. There is now strong presumptive evidence 

 that all cases of endocarditis are due to bacterial infection. In 

 the simple or vegetative form, so often the result of acute 

 rheumatism, the micrococcus rheumaticus (p. 221) has been 

 cultivated from the valves in a certain number of cases, and is 

 probably the causal agent in most instances. 



Endocarditis of the ulcerative type may be produced by 

 various organisms, chiefly pyogenic. Of these the staphylococci 

 and streptococci are most frequently found. In some cases of 

 ulcerative endocarditis following pneumonia the pneumococcus 

 (Fraenkel's) is present ; in these the vegetations often reach a 

 large size and have not so much tendency to break down as in 

 the case of staphylococcus infections. Other organisms have 

 been cultivated from different cases of the disease, and some of 

 these have received special names; for example, the diplo- 

 coccus endocarditis encapsulatus, bacillus endocarditidis griseus 

 (Weichselbaum), and others. In some cases the bacillus coli 

 communis has been found, and occasionally in endocarditis 

 following typhoid the typhoid bacillus has been described as the 

 organism present, but further observations on this point are 

 desirable. The gonococcus also has been shown to affect the 

 heart valves (p. 256), though this is a very rare occurrence. 

 Tubercle nodules on the heart valves have been found in a few 

 cases of acute tuberculosis, though no vegetative or ulcerative 

 condition is produced. 



In some cases, though we believe not often, the organisms 

 may attack healthy valves, producing a primary ulcerative endo- 

 carditis, but more frequently the valves have been the seat* of 

 previous endocarditis, secondary ulcerative endocarditis being 

 thus produced. In some cases, especially when the valves have 

 been previously diseased, the source of the infection is quite 

 obscure. It is evident that as the vegetations are composed for 

 the most part of unorganised material, they do not offer the 

 same resistance to the growth of bacteria, when a few reach them, 

 as a healthy cellular tissue does. On microscopic examination 

 of the diseased valves the organisms are usually to be found 

 in enormous numbers (Fig. 59). By their action breaking 

 down of the vegetations occurs, and the emboli thus produced 

 act as the carriers of infection to other organs, and give rise to 

 secondary suppurations. 



