Commercial latex agglutination for detection of group B streptococcal antigen in body fluids

Abstract

SEVERAL TECHNIQUES for the detection of bacterial antigens in body fluids have been shown to be helpful in providing a rapid, specific etiologic diagnosis prior to culture results in infants and children with meningitis and bacteremia. For the detection of group B streptococcal (GBS) antigen, these include countercurrent immunoelectrophoresis (CIE), ~4 latex agglutination 5-7 and slide coagglutination tests, 8 and enzyme immunoassay) Among these, latex agglutination is simple, rapid, and has the advantage of somewhat greater sensitivity than CIE and greater specificity than coagglutination. When a commercially available latex reagent (Streptex) was used for the detection of GBS antigen in cerebrospinal fluid (CSF), serum, and concentrated urine of infants with GBS infection, respectively 78.6%, 26.7%, and 93.3% of specimens were positive. 6 False positive results were rare. Recently a similar but more sensitive reagent (Wellcogen Strep B) has been prepared specifically for testing of body fluids. We describe the sensitivity and specificity of this latex agglutination assay in detecting GBS antigen in CSF and concentrated urine from infants with and without systemic GBS infection.