Of the many methods available for antigen and antibody detection, LA, ELISA, RIA, CIE, and COA are the most widely used. Latex agglutination (LA) employs latex polystyrene particles' sensitized by either antibody or anti gen. LA is more sensitive than CIE and COA but slightly less sensitive than either RIA or EIA. LA has been used to detect H. influenzae, Neisseria meningitidis, and S. pneumoniae antigens in cerebrospinal fluid. LA has also been used for detection of cryptococcal antigen. Most recently, LA has been widely used for rapid detection of group. A streptococcal antigen directly from the pharynx. The test is rapid (five minutes), sensitive (approximately 90%), and specific (99%).