Agglutination latex

Latex agglutination immunoassays are easily formatted into simple kits which can provide yes/no and semiquantitative estimates of antigen (or antibody) in a sample. The first such assay was developed in 1957 for rheumatoid factor (15) and assays are on the market for the deterrnination of many species of bacteria, fungi. Mycoplasma, parasites, ckettsia, and vimses, as well as for the deterrnination of autoimmune disease, hormones (qv), dmgs (see Pharmaceuticals), and blood proteins (16). Latex agglutination is also the basis of many home pregnancy tests. 

If CSF Gram stain and/or culture is negative, rapid diagnostic tests (such as latex agglutination) may be useful these tests are positive even if bacteria are dead. 

Serological methods (mostly requiring one day) Latex agglutination... 

Antigens to C. neoformans can be detected by latex agglutination. C. neoformans can be detected in approximately 60% of patients by India ink smear of CSF and cultured in more than 96% of patients. 

Latex acrylic polymers, 22 41-43 Latex agglutination immunoassays, 14 141 Latex-based paper coatings, 1<8 124-125 Latex manufacturing equipment, 14 720, 721... 

Immunological methods Methods such as gel-agglutination tests were introduced many years ago (according to Outcherlony) however they are not sufficiently sensitive. Reversed passive latex agglutination kits (SET-RPLA and TST-RPLA) are presently applied for enterotoxin detection and are more sensitive than gel diffusion (Wieneke, 1988). The ELISA technique is also very popular - toxins are detected via VIDAS STAPH ENTEROTOXIN SET and indirect double sandwich ELISA (Meyrand et al., 1998). 

S10. Sawai, M., Sudo, T., Okumura, H., Morita, S., Sato, S., Matsumoto, S., and Migita, S., A new photometric immunoassay of latex agglutination reaction with near infrared tur-... 

For enzyme inhibition assays, urine is the preferred specimen [4]. Interestingly, Bik can be measured by the inhibition of trypsin in urine but not in plasma. Urinary Bik analysis may also be performed by antibody staining, latex agglutination, and radioimmunoassay (RIA) [4]. Despite the analytical approach used, all Bik forms are measured together. The enzyme inhibition method involves adding known amounts of trypsin to the specimen and monitoring trypsin inhibition. Trypsin activity is assessed by detection of by-products from a cleavable substrate. Dipstick methods are available for the rapid detection of trypsin inhibitors in urine [15, 17 19]. 

Figure 5.6. Percentage of samples from Mycobacterium tuberculosis (TB) patients and healthy controls exhibiting different degrees of agglutination when tested using the conventional slide prooedure or the US-enhanced latex agglutination test. (Reproduced with permission of Elsevier, Ref [76].)...

Clostridium difficile can be cultured from the stool, and toxins A and B can be assessed by different techniques (116). The most accurate method is still a cytotoxin tissue culture assay. This detects the cytopathic effect of cytotoxin B, which can be neutralized by Clostridium sordellii antitoxin, but it takes 24 8 hours to show a result. Alternative tests that produce faster results have been developed. A latex agglutination test lacks sensitivity and specificity, and does not distinguish toxigenic from non-toxigenic strains. An enzyme immunoassay for toxin A may be an acceptable alternative to the cell cytotoxin assay and the results are rapidly available. A dot immunobinding assay has not yet been extensively studied (164). 

Woods GL, Iwwen PC. Comparison of a dot immunobind-ing assay, latex agglutination, and cytotoxin assay for laboratory diagnosis of Clostridium difficile-associated diarrhea. J Clin Microbiol 1990 28(5) 855-7. 

Diarrhea developed in a 60-year-old man on chronic hemodialysis after 20 doses of parenteral vancomycin (250 mg at each dialysis) (57). Although culture for C. difficile was not performed, latex agglutination was positive for C. difficile toxin. 

The staphylococcal toxin must be separated from food constituents and concentrated to detect trace amounts. The toxin is then identified by specific precipitation with antiserum as follows (1) the selective adsorption of the enterotoxin from an extract of the food onto ion exchange resins and (2) the use of physical and chemical procedures for the selective removal of food constituents leaving the enterotoxin in solution. More recently rapid methods based on monoclonal antibodies (e.g., enzyme-linked immunosorbent assay, reverse passive latex agglutination) have been developed for detecting very low levels of enterotoxin in food. 

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