The conception of rheumatic fever as an infectious disease has led many investigators to attempt to isolate the causative organism from the blood. The results of these studies have been contradictory, and at present there is no unanimity of opinion regarding the existence of a characteristic organism or the frequency with which any organism can be isolated.
Achalme1 in 1891 isolated a large spore-bearing anaerobic bacillus from the blood at autopsy in cases of rheumatic fever. This was later thought to be the Welch bacillus. The etiologic importance of this finding is nullified by the failure of other workers to confirm it, and also by the fact that such anaerobes are not uncommonly found at necropsy in a variety of diseases.
Blaxall2 (1896) found minute gram-negative bacilli with marked polar staining in the blood and synovial fluid of arthritic patients. They apparently had chronic rheumatoid arthritis and not
LESLIE CJ, SPENCE MJ. BACTERIOLOGY OF BLOOD IN RHEUMATIC FEVER. Am J Dis Child. 1938;55(3):472–486. doi:10.1001/archpedi.1938.01980090020003