The etiology of acute nephritis is no longer open to argument. General agreement exists that except in those rare instances of nephritis produced by chemical irritants, such as mercuric chlorid, the invariable cause of acute inflammation of the kidneys is bacterial invasion from some primary source or focus situated elsewhere. The pathogenic organism in the overwhelming majority of cases is the streptococcus. The etiology is usually apparent in a comparatively recent tonsillitis, rheumatism or other form of streptococcus infection with or without endocarditis. In both acute and subacute cases, streptococci may often be found in the urine.
Ophüls insists that there exists no sharp line of division in anatomic features between acute, subacute and chronic nephritis. They appear to be different grades of the same pathologic process. By inference and analogy we might expect chronic nephritis to possess the same etiology as more recent and acute forms of the disease;