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PubMed2000

Immune-mediated agglutination of cytoskeleton-free RBC microvesicles.

BACKGROUND: The factors contributing to RBC agglutination are complex. The RBC cytoskeleton's participation in and contribution to this phenomenon are difficult to separate from those of the plasma membrane. Immunoreactive, cytoskeleton-free, band 3-enriched microvesicles can be generated from normal RBCs. Band 3 has been defined as an important antigen in autoimmune hemolytic anemia (AIHA). STUDY DESIGN AND METHODS: RBC microvesicles devoid of major cytoskeletal proteins were generated and sensitized with eluates obtained from AIHA patients, DAT-positive blood donors, and antisera to common RBC antigens. Monoclonal anti-human IgG was added and agglutination was investigated. Autoantibody-specific binding was evaluated by employing (125)I protein A. RESULTS: RBC vesicle agglutination with a 4+ anti-human globulin score was obtained with 10 autoantibody eluates from AIHA patients and anti-D (3+), but not with eluates from 20 DAT-positive blood donors or antisera directed to eight other common RBC antigens. Microvesicles sensitized with AIHA eluates bound 67 to 167 times as much (125)I protein A radioactivity as did those incubated with buffered normal saline and 18 to 45 times more than vesicles incubated with normal serum. CONCLUSION: The major proteins of the RBC cytoskeleton are not required for supporting IgG immune-mediated agglutination of RBC microvesicles.

Anemia, Hemolytic, Autoimmune↗
PubMed2001

A novel microplate agglutination method for blood grouping and reverse typing without the need for centrifugation.

BACKGROUND: Current agglutination tests and solid-phase adherence methods, employed as the techniques for RBC typing and antibody screening, require centrifugation and washing steps. This report describes a novel agglutination method for forward and reverse grouping that is based on the formation of an RBC monolayer on a microplate without the need for centrifugation and washing. STUDY DESIGN AND METHODS: In a comparative study, 2225 samples from healthy regular blood donors were tested for ABO, Rh (D, C, c, E, and e), K, and reverse grouping, in parallel, by the new microplate agglutination method and a commercially available blood testing system, which served as a reference method. RESULTS: In the case of forward grouping, 0.37 percent of samples tested were false negative in the new method and 1.35 percent tested false negative in the reference blood testing system. In addition, the reverse grouping reference method showed 0.4 percent false-positive and 2.6 percent false-negative results. In contrast, the new method gave false-positive results in only 0.09 percent and false-negative results in 0.67 percent of the cases tested. CONCLUSION: These results, as well as the possibility of adapting this method to a fully automated system, suggest that our novel agglutination method could be an important contribution to the field of immunohematology.

Blood Grouping and Crossmatching↗
PubMed1993

Rapid detection of plasma glycocalicin by a latex agglutination test. A useful adjunct in the differential diagnosis of thrombocytopenia.

To aid in the rapid differential diagnosis of thrombocytopenia, the authors developed a latex agglutination test for glycocalicin, a proteolytic fragment of platelet membrane glycoprotein Ib. Plasma glycocalicin determinations were performed for 34 patients with thrombocytopenia. Plasma samples from four patients with aplastic anemia and ten patients with myelodysplastic syndromes, all with glycocalicin levels less than 0.6 mg/L by an enzyme-linked immunosorbent assay, all had negative results by the latex test. In contrast, positive latex agglutination titers were obtained for all 12 patients with idiopathic thrombocytopenic purpura. Eight patients with liver cirrhosis and splenomegaly had elevated levels of plasma glycocalicin, and all of their plasma samples produced agglutination. This latex agglutination test for glycocalicin allows a rapid discrimination of thrombocytopenia caused by impaired platelet production from that caused by increased platelet destruction; thus, it is suitable for use as a screening test in a routine clinical laboratory.

Adolescent↗
PubMed1986

Latex agglutination tests for detection of Candida antigens in sera of patients with invasive candidiasis.

The utility of two latex agglutination tests in detecting antigenemia in patients with invasive candidiasis was studied. To perform one test, we treated sera with protease and heat to free mannan from antibodies to mannan. Latex beads coated with antibodies to mannan detected mannan in supernatants. In the second test, untreated sera were tested for capacity to agglutinate a commercially available preparation of latex beads coated with antibody to Candida. Two panels of sera were analyzed with the tests. One comprised 355 sera sequentially collected from 75 leukemic patients who underwent 97 episodes of chemotherapy resulting in neutropenia. The other panel comprised 364 sera collected only at the time candidiasis was suspected from 150 patients with a variety of underlying diseases. Of 23 episodes of invasive candidiasis in leukemic patients, antigenemia was detected in 18 (78%) by the mannan latex agglutination test and in 11 (48%) by the commercial test. For the second serum panel the respective tests detected antigenemia in only 22% and 19% of patients with invasive candidiasis. While latex agglutination tests for circulating Candida antigens may be useful for diagnosing invasive candidiasis, the transient nature of antigenemia requires frequent testing of patients' sera and limits the usefulness of the tests in diagnosing invasive candidiasis.

Antigens, Bacterial↗
PubMed1976

Factors involved in concanavalin A agglutination of KB and NC37 cells grown in suspension culture.

NC37 and KB cells grown in suspension culture remained agglutinable at 23 degrees C by concanavalin A (Con A) after sufficient glutaraldehyde fixation to prevent lateral mobility (clustering) of Con A binding sites. In contrast, at 4 degrees C agglutination of the fixed cells was blocked. No significant differences in 3H-Con A binding were observed between unfixed cells and glutaraldehyde-fixed cells at 23 degrees C and unfixed cells at 4 degrees C. Con A bound to fixed cells at 4 degrees C produced agglutination when the cells were washed and then warmed to 23 degrees C. Thus a cold-sensitive factor unrelated to the binding of Con A or the clustering of Con A sites is necessary for agglutination to occur.

Binding Sites↗
PubMed1983

Assessment of a latex-agglutination-inhibition card test for serum gentamicin, with a study of the effects of potential interfering factors.

A latex-agglutination-inhibition test for serum gentamicin, based on inhibition by gentamicin of antibody-induced agglutination of gentamicin-coated latex particles, was found to be sufficiently reliable for use in therapeutic monitoring and to correlate well with a variety of established immunoassays. The test (a nonseparation, nonisotopic immunoassay) is performed on cards and has a simple visual end point by inspection for the presence or absence of agglutination. Severely elevated bilirubin or lipid levels, or gross hemolysis (which may cause interference with other nonseparation immunoassays) had no effect on the card test. With raised rheumatoid factor or complement, the cards gave accurate recovery of added gentamicin at 5 and 10 mg/L but low recovery at 2 mg/L. Of 67 patients' sera, three from one individual caused nonspecific agglutination of the latex and could not be assayed. The card test can be recommended for laboratories handling infrequent or small numbers of samples and for those without access to instrumentation.

Fluorescent Antibody Technique↗
PubMed2004

Cerebrospinal latex agglutination fails to contribute to the microbiologic diagnosis of pretreated children with meningitis.

We conducted a 10-year retrospective study of all children who had cerebrospinal fluid latex agglutination testing for bacterial antigens performed at 1 tertiary care urban children's hospital. Of the 176 patients with culture-negative meningitis who were pretreated with antibiotics before lumbar puncture, none had a positive latex agglutination study (0 of 176; 95% confidence interval, 0-2%). Latex agglutination studies identified no additional cases of bacterial meningitis beyond those identified by culture in pretreated patients. Clinical decision-making algorithms for the management of pretreated patients at risk for bacterial meningitis should not include latex agglutination testing.

Adolescent↗
PubMed1998

A rapid latex agglutination assay for the detection of penicillin-binding protein 2'.

A simple and rapid slide latex agglutination assay was developed to detect penicillin-binding protein 2' (PBP2') from isolates of staphylococi. PBP2' present in the membranes of methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant coagulase negative staphylococci (MRCNS) was rapidly extracted by alkaline treatment and, by combining with a slide agglutination reaction using latex particles sensitized with monoclonal antibodies raised against it, PBP2' could be detected from a single loopful of cells taken from agar plates not containing beta-lactum antibiotics within 15 min. In a study of clinical isolates previously characterized as either MRSA or methicillin-susceptible Staphylococcus aureus (MSSA) by antibiotic susceptibility testing, 231 specimens of 232 MRSA were PBP2' positive by latex agglutination, and the 87 specimens of MSSA were all negative. One specimen identified as MRSA by susceptibility testing but PBP2' negative by latex agglutination was confirmed as mecA gene negative by PCR. This simple and rapid slide latex reagent should be useful in clinical diagnostics.

Animals↗
PubMed1997

[Evaluation of a latex agglutination method for detecting and characterizing verotoxin (VT) produced by Escherichia coli].

The detection of VT produced by Escherichia coli is very important for the identification of verotoxin-producing Escherichia coli (VTEC). The latex agglutination reagents (Denka Seiken Co. Ltd, Tokyo) which was developed to detect VT was compared with the vero cell bioassay or polymerase chain reaction method. A total 147 VT-positive strains (109 serotype O157:H 7/- and 38 non-O157 serotype) and 31 VT-negative strains which were isolated from human were investigated. In addition, a total of 79 VT-positive strains (14 serotype O157:H7/- and 65 non-O157 serotype) and 79 VT-negative strains which were isolated from animals were also examined. The latex agglutination assay for the human isolates showed the 100% sensitivity, specificity and agreement. The assay for the animal isolates showed 94.9% sensitivity, 100% specificity and 97.5% agreement. Although 4 of 8 strains isolated from swine which produce VT2 variant toxin (VT2e) failed in detecting verotoxin by latex agglutination assay, VT2e was not related to human infections. We conclude that this latex agglutination reagent is highly sensitive and specific for detecting and characterizing VT of E. coli. The method is reliable, easy to perform at any laboratories.

Animals↗
PubMed1981

Latex agglutination inhibition card test for gentamicin assay: clinical evaluation and comparison with radioimmunoassay and bioassay.

Gentamicin levels were determined in 100 serum specimens by a new latex agglutination inhibition card test, a radioimmunoassay (RIA), and a bioassay. Correlation coefficients determined by linear regression analysis demonstrated that the levels obtained by the latex agglutination inhibition card test had a high degree of correlation with the RIA and could be performed much faster and more economically when processing small numbers of specimens. The bioassay had a slightly lower degree of correlation with both the RIA and the latex test and was adversely influenced by concurrently administered antibiotics which could not be eliminated by beta-lactamase. When measuring gentamicin concentrations above 2 micrograms/ml, the coefficient of variation was less than 14% for the latex agglutination assay compared with 15% for the bioassay and 12% for RIA. The latex agglutination inhibition card test is a rapid, accurate, specific, and reproducible method for monitoring gentamicin levels in patients and is particularly applicable for laboratories processing small numbers of specimens.

Animals↗
PubMed1981

Participation of pili and cell wall adhesion in the yeast agglutination activity of Escherichia coli.

Escherichia coli strain 2699 (O6:K13) which had been isolated from a case of urinary tract infection exhibited pili during the stationary phase (24 to 40 h), but not during the exponential phase (4 h), when grown in static broth culture. The bacteria were also piliated when grown for 24 h on agar. They agglutinated Saccharomyces cerevisiae (baker's yeast) in the piliated as well as in the nonpiliated state. The agglutinations were mannose sensitive, i.e., they could be inhibited with 50 mM methyl-alpha-mannoside. The bacteria were first depiliated by shearing and then used for the isolation of outer membrane vesicles with an Omnimixer. Purified pili and outer membranes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electron microscopy. The pili could be demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis only after treatment at low pH or in saturated guanidine hydrochloride which is typical of the common type 1 pili. Depiliated bacteria, purified pili, and purified outer membranes gave mannose-sensitive agglutination of S. cerevisiae. The findings are discussed with respect to possible mechanisms of cell agglutination.

Agglutinins↗
PubMed1982

Evaluation of a commercial latex agglutination test for identification of Staphylococcus aureus.

A new, commercially available latex agglutination test (SeroSTAT Staph; Scott Laboratories, Inc., Fiskeville, R.I.) was compared with the tube coagulase and slide coagulase tests as means for identifying Staphylococcus aureus. Of 160 clinical isolates of S. aureus, 159 (99.4%) yielded positive results with the latex agglutination test. Negative latex agglutination test results were obtained with 266 of 267 clinical isolates of Micrococcus spp. and staphylococcal species other than S. aureus (99.6%). The latex agglutination test was found to be a rapid, technically nondemanding method for identifying S. aureus. It was as accurate as the tube coagulase test and more accurate than the slide coagulase test.

Coagulase↗
PubMed1985

Comparison of enzyme-linked immunosorbent assay, hemagglutination inhibition, and passive latex agglutination for determination of rubella immune status.

Hemagglutination inhibition, enzyme-linked immunosorbent assay (ELISA), and passive latex agglutination were used to test 495 human serum samples for determination of rubella immunity. Overall agreements for immune status were as follows: hemagglutination inhibition versus ELISA, 94.7% (469 of 495); hemagglutination inhibition versus passive latex agglutination (1:10 dilution), 99.2% (491 of 495); and passive latex agglutination (1:10 dilution) versus ELISA, 94.7% (469 of 495). Both ELISA and passive latex agglutination are satisfactory for rubella immunity screening, with the reservation that the ELISA method examined yielded a large number of false-negative results.

Adult↗
PubMed1985

Comparison of a latex agglutination test with five other methods for determining the presence of antibody against cytomegalovirus.

A latex agglutination test for determination of antibody against cytomegalovirus was compared with five other methods: a solid-phase fluorescent immunoassay, an indirect hemagglutination test, two solid-phase enzyme immunoassays, and an indirect fluorescent-antibody method, with sera collected from 210 random blood donors. Of the sera tested, 28% were positive for anti-cytomegalovirus by concordance of four or more methods. The latex agglutination test performed well, with a sensitivity of 100%, a specificity of 99%, and positive and negative predictive values of 97 and 100%, respectively. The methods were also evaluated for the number of sera requiring repeat testing, equivocal results after retesting, ease of performance, turnaround time, and technical demands. The tests which best met the requirements for a screening test were the solid-phase fluorescent immunoassay, the indirect hemagglutination test, and the latex agglutination test. The latex agglutination test is a valuable screening tool for detecting total anti-cytomegalovirus which has high sensitivity, high negative predictive value, and rare equivocal results and also has the added advantages of ease of performance and rapid turnaround time.

Antibodies, Viral↗
PubMed1988

Detection of staphylococcal exfoliative toxin by slide latex agglutination.

A simple and rapid method in which slide latex agglutination was used was developed to detect the exfoliative toxin (ET) elaborated by clinical isolates. ET types A and B (ET-A and ET-B) were purified by plate gel isoelectrofocusing, and anti-ET sera were obtained by immunizing rabbits. A specific immunoglobulin G antitoxin was then prepared from the immunized rabbit sera by fast protein liquid chromatography, and latex particles were coated with the antitoxin. Of 74 staphylococcal strains isolated from patients with staphylococcal scalded skin syndrome, 61 strains were found to produce ET by the newborn mouse bioassay. All 61 strains were shown to be positive for ET-A and ET-B production by the slide latex agglutination method. The lowest concentration of ETs detected by the latex agglutination method was 0.5 microgram/ml, which was much lower than that detected by the double immunodiffusion method, with a sensitivity of 50 micrograms/ml. It is crucial to prove ET production by clinical isolates for the diagnosis and surveillance of staphylococcal scalded skin syndrome. The latex agglutination method is a sensitive, simple, and rapid test which can be used as an alternative to the newborn mouse bioassay.

Animals↗
PubMed1992

Latex agglutination-negative methicillin-resistant Staphylococcus aureus recovered from neonates: epidemiologic features and comparison of typing methods.

An unusual strain of methicillin-resistant Staphylococcus aureus (MRSA) was repeatedly isolated from infants in a newborn special care unit (NBSC) and a newborn intensive care unit. Between January 1989 and March 1990, approximately 100 isolates from infected or colonized infants were recovered. Surveillance cultures taken during this time revealed a 20% colonization rate, which was defined as recovery of MRSA from the nares, umbilicus, or groin. Isolates were identified as S. aureus by tube coagulase reactivity and heat-stable nuclease production but were unreactive in a latex agglutination assay. Representative isolates that were collected during the outbreak and that were found to share the latex agglutination assay-negative phenotype were compared by antibiogram (12 isolates), bacteriophage typing (20 isolates), capsular polysaccharide typing (30 isolates), and plasmid as well as chromosomal DNA analyses (20 isolates). All isolates known to be associated with the outbreak had nearly identical antibiograms and were notably susceptible to clindamycin. Staphylococcal bacteriophage typing was not useful in determining the relatedness of the isolates, since the majority were nontypeable. Plasmid pattern analysis revealed one large plasmid (approximately 100 kb) of equivalent size among the isolates. Capsular polysaccharide typing revealed that 14 of 30 isolates tested were type 5. Isolates identified in children at two other hospitals in the city which were also unreactive by the latex agglutination assay and clindamycin susceptible had plasmid and antibiogram patterns identical to those of isolates from the NBSC. Pulsed-field gel electrophoresis of restriction enzyme-digested genomic DNAs from the outbreak isolates demonstrated identical patterns which could be clearly differentiated from those of other unrelated MRSA. The strain from the NBSC is, therefore, unique and underscores the need for caution in interpreting the latex agglutination reactivities of MRSA isolates.

Bacterial Typing Techniques↗
PubMed1992

Latex agglutination assay of human immunoglobulin M antitoxoplasma antibodies which uses enzymatically treated antigen-coated particles.

An assay of immunoglobulin M (IgM) antitoxoplasma antibodies which is rapid (less than 30 min), homogeneous, and reliable (interassay coefficient of variation, less than 11%) is proposed. Its principle is based on the observation that a suspension of latex particles coated with toxoplasma antigens, after treatment with proteinase K, becomes less agglutinable by IgG antibodies but more agglutinable by IgM antibodies. The difference between the activities of the two classes of antibodies is increased by the addition of a monoclonal antibody directed against the Fc region of IgM. Agglutination is measured with a special instrument which optically counts the particles that remain free after the reaction. Turbidimetric reading, although less sensitive, is also suitable. No significant interferences either by IgG antitoxoplasma antibodies or by rheumatoid factor or antinuclear antibodies were observed. The sensitivity was similar to that of the immunosorbent agglutination assay.

Animals↗
PubMed1996

Multicenter evaluation of four methods for Clostridium difficile detection: ImmunoCard C. difficile, cytotoxin assay, culture, and latex agglutination.

A three-center study was undertaken to compare several test methods for the detection of Clostridium difficile, associated toxin, or related markers by using 927 stool specimens. Methods included direct assay of cytotoxin in stool by tissue culture, C. difficile bacterial culture followed by cytotoxin assay, bacterial culture alone, latex agglutination assay, and the ImmunoCard C. difficile test (Meridian Diagnostics, Inc.). The sensitivities, as determined against direct cytotoxin assay results, of the ImmunoCard C. difficile and latex agglutination assays were 84 and 67%, respectively (92 and 77%, respectively, when adjusted for bacterial culture outcomes). Evaluation for C. difficile-associated disease (CDAD) among 864 patients was based on clinical criteria for antibiotic-associated diarrhea combined with laboratory evidence of toxin or toxin-producing C. difficile in stool specimens. The sensitivity of each test method for screening of CDAD was as follows: bacterial culture, 95%; culture with cytotoxin assay of isolates, 90%; ImmunoCard C. difficile test, 83%; cytotoxin assay 82%; and latex agglutination assay, 67% (P < or = 0.05 versus all other methods). The standard deviations of the test sensitivity statistics between study sites were ranked as follows: cytotoxin assay (+/- 3.1%) < ImmunoCard C. difficile test (+/- 5.7%) < latex agglutination assay (+/- 12.3%) < culture (+/- 24.7%) < culture with cytotoxin assay (+/- 28.0%). The data support the use of the ImmunoCard C. difficile test as an adjunct for the diagnosis of CDAD.

Bacterial Toxins↗