The Use of the Serum Opacity Reaction in the Typing of Group-A Streptococci
Maxted, W. R. and Widdowson, Jean P. and Fraser, Cherry A. M. and Ball, Lyn C. and Bassett, D. C. J.,, 6, 83-90 (1973),
doi = https://doi.org/10.1099/00222615-6-1-83,
publicationName = Microbiology Society,
issn = 0022-2615,
abstract= SUMMARY A large collection of group-A streptococci was examined for the production of opacity in horse serum and for the presence of M and T antigens. Opacity production is a constant character of certain M types and is consistently absent from the rest. Testing for opacity production is a valuable addition to the serological typing procedure especially if it is carried out first. It has proved useful in (1) reducing the number of tests with M antisera that have to be set up and (2) drawing attention to errors in M typing due to the presence of cross-reacting precipitins in typing sera. The serological specificity of the opacity factor corresponds to that of the M antigen. Inhibition of opacity production therefore provides a useful alternative method of typing strains that form the opacity factor. M antisera for opacity-producing serotypes are often of poor quality and difficult to prepare. In these circumstances, the opacity inhibition test has proved useful for preliminary identification of new M types of streptococci.,
language=,
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