True statement about Antistreptolysin '0' titre is ?

Ans. is 'b' i.e., In acute glomerulonephritis titre is low . In rheumatic fever and glomerulonephritis, a retrospective diagnosis of streptococcal infection may be established by demonstrating high levels of antibody to streptococcal toxins. The usual test done is antistreptolysin 0 titration. . ASO titres higher than 200 units is considered significant and suggests either recent or recurrent infection with streptococci. (ie ASO titres > 200 units does not mean rheumatic fever, it only indicates recent or recurrent infection). . High levels are usually found in acute rheumatic fever but in glomerulonephritis, titres are often low. . Streptozyme test is a passive hemagglutination test (not active haemagglutination). Note ? . In skin infection ASO titre is not high and ASO estimation has not much clinical significance. . In Pyoderma (skin infection) and acute glomerulonephritis, anti DNAse and antihyaluronidase are used for retrospective diagnosis.