Automated Microtitration Test for Antistreptolysin O

A commercially available instrument that automatically makes serial dilutions and delivers reagents was used for the determination of antistreptolysin O titers in serum. The automated method was compared with tube-dilution and manual microtitration techniques. It gave higher reproducibility of results and was quicker to perform than both the other tests; and it was much more economical in reagents than the tube test. The automated technique is considered to be the best of the three methods when more than a small number of specimens are examined at one time. It is now in routine use in our laboratory.     

Comparison of the Streptozyme Test with the Antistreptolysin O, Antideoxyribonuclease B, and Antihyaluronidase Tests

The streptozyme test was compared with the antistreptolysin O (ASO), antideoxyribonuclease B (ADN-B), and antihyaluronidase (AH) tests. One hundred and twenty-seven human serum specimens were tested by each of the four tests. The streptozyme test detected more specimens with elevated titers than any single test; however, it was not as effective as the combination of the ASO and ADN-B tests. The streptozyme test appears to be particularly useful for laboratories which rely solely on the ASO test for serological evidence of a streptococcal infection. The test can be used in these laboratories to screen all specimens with low ASO titers (<170) for the detection of ADN, AH, antinicotinamide adenine dinucleotidase, and antistreptokinase.     

Comparison of a Newly Developed Latex Agglutination Test and an Immunodiffusion Test in the Diagnosis of Systemic Candidiasis

A newly developed latex agglutination (LA) test and a modified immunodiffusion (ID) test were evaluated. The antigen used was a homogenate of Candida albicans. A total of 167 antisera were employed in the evaluation. They included 36 sera from clinically well persons; 78 from patients with various clinical forms of candidiasis; 52 from patients with proven cases of aspergillosis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, nocardiosis, paracoccidioidomycosis, sporotrichosis, and tuberculosis; and one serum from a patient with toruloposis. Use of the LA test in conjunction with the ID test permitted the detection of more than 90% of 43 proven candidiasis cases. Of all the heterologous cases and normal human sera tested, LA reactions were noted with 3 of 10 cryptococcosis case specimens, 1 of 9 tuberculosis case specimens, and with the torulopsemia case serum. In contrast, the only heterologous serum reactive in the ID test was that from the patient with torulopsemia. Torulopsis glabrata and C. albicans antisera gave identical reactions in LA and ID tests with T. glabrata or C. albicans antigens. ID tests with selected antigens, however, permitted differentiation of rabbit and human T. glabrata antibody from that of C. albicans antibody. Six different precipitins were recognized with the C. albicans antigens. The occurrence of multiple precipitin lines and high LA titers was suggestive of severe candidiasis. The LA test, in contrast to the ID test, appeared to have prognostic value. Together, the LA and ID tests provided a simple, rapid, and accurate means of detecting and monitoring infections by species of Candida.     

Effect of Type of Red Blood Cells on Antistreptolysin O Titer

Antistreptolysin O (ASO) titers were determined on 117 human sera with rabbit, human, and sheep red blood cells (RBC) as the indicator system in the ASO tube test. The titers of 65% of the sera were one dilution step higher when a 5% suspension of sheep RBC was used instead of a 5% suspension of rabbit RBC. Titers were one dilution step higher in 42.7% of the sera when a 5% suspension of human RBC was used instead of a 5% suspension of rabbit RBC. The best comparability of titers was between a 5% suspension of human RBC and a 2.5% suspension of sheep RBC.     

Evaluation of Streptozyme and Antistreptolysin O Tests in Streptococcal Pyodermal Nephritis

The evaluation of the streptozyme test in sera from 34 patients with streptococcal pyodermal nephritis was studied. Ninety-seven percent of the patients developed high titers of antistreptozyme antibodies on the first bleeding after hospitalization, in contrast to only 40% of patients who developed elevated antistreptolysin O titers. The high antistreptozyme titers declined during convalescence and reached normal levels in the sixth month after onset of the disease. The most significant fall in titers occurred between 1 and 2 months from the onset of disease. The streptozyme test may be particularly helpful as a rapid screening test for antibodies in streptococcal pyodermal nephritis.     

Detection of Hepatitis Associated Antigen by the Latex Agglutination Test

Hepatitis associated antigen may be detected quickly and reliably by the latex agglutination test, using antiserum from guinea pigs immunized with the antigen. The latex test has a sensitivity comparable to the counter current immunoelectrophoresis technique.     

Latex Test for Quantitative Determination of Escherichia coli Antibody

A latex agglutination test was developed for assay of anti-Escherichia coli antisera. The test is simple, specific, sensitive, and reproducible.     

The use of a Rapid Salmonella Latex Serogrouping Test (Spectate) to assist in the confirmation of ELISA-based Rapid Salmonella Screening tests

S. CHEESBROUGH AND C. DONNELLY. 1996. Spectate, a 10 min, simple, latex-based agglutination test for serogrouping of salmonellae, has been investigated as a tool to assist in the confirmation of ELISA presumptive positive broth samples when screening for salmonellae in foods. When obtaining a combined ELISA and Spectate positive result, there was a 90% (27/30) confidence limit of a genuine positive result, some one or two working days quicker than the traditional methods. Of the 10% (3/30) that were not confirmed as salmonellas, two gave a Spectate result which is advised as being a possible Citrobacter spp. and one sample gave a positive confirmation by Spectate only, which suggested a failure of the traditional confirmation process, a finding confirmed at other sites. Extensive studies performed at several food company microbiology laboratories showed Spectate to be a useful additional tool in the confirmation process of ELISA screening techniques for salmonellae in food. Additionally the concept of a 'false positive' may need to be refined to that of a 'not culturally' positive, given the apparent possible failure of the traditional confirmation methods.     

Screening Test of Microbes

Potent bacteria for production of chillproofing enzyme were isolated during screening tests on 1670 strains of microorganisms.

All but one of these bacteria were classified as Serratia marcescens and the exceptional strain was tentatively designated as B–103. These bacteria produced an extracellular proteolytic enzyme which prevented chill haze of beer.     

Evaluation of a Microtiter Latex Agglutination Test for Histoplasmosis

Experiments were designed to evaluate a Microtiter latex agglutination (Micro-LA) test, as a serological aid in the diagnosis of histoplasmosis, and to compare this test with the conventional microtiter-complement fixation (CF) test for histoplasmosis. Sera tested were from cases of acute and chronic pulmonary and disseminated histoplasmosis, as well as from individuals not having histoplasmosis. Ninety-seven percent of the cases of acute pulmonary histoplasmosis had positive Micro-LA tests, whereas 91% had positive CF tests. Ninety-six percent of the patients having chronic pulmonary histoplasmosis showed positive Micro-LA tests and 91% had positive CF tests. In contrast, 64% of the cases of disseminated histoplasmosis had positive Micro-LA tests, whereas 82% had positive CF tests. None of these differences was statistically significant. Although there were no significant differences in complement fixing and agglutinating antibody cross-reactivity with Blastomyces antigens, more patients demonstrated CF titers than Micro-LA titers. Sera from patients with acute and chronic histoplasmosis showed higher Micro-LA titers than CF titers, whereas sera from cases of disseminated histoplasmosis showed higher CF titers. Histoplasmin skin testing has less of a boosting effect on agglutinating antibodies than on CF antibodies to histoplasmin. Anticomplementary sera can be used in the Micro-LA test. This test is simple to perform, and results can be obtained in 2 to 4 hr.     

Detection of Escherichia coli Antigens by a Latex Agglutination Test

A latex particle agglutination technique to detect ethylenediaminetetraacetate-solubilized extracts from Escherichia coli and whole E. coli cells is described. The sensitivity of the serological test was found to be 0.5 to 2.5 ng for the solubilized antigens and 1.5 x 10(6) to 5.7 x 10(6) cells per ml for the particulate antigens. The test was 100 to 1,000 times more sensitive than the standard bacterial agglutination test. Furthermore, it detected E. coli antigens during all phases of bacterial growth, whereas the bacterial test detected the antigens only after the mid-log phase. No significant cross-reactivity was observed between latex-anti-E. coli preparations and heterologous bacterial strains used in the experimental procedure. A buffer formula containing fatty acid-free bovine albumin prevented nonspecific aggregation of the latex particles.     

Evaluation of a Commercial Latex Agglutination Test Kit for Cryptococcal Antigen

Two dozen Crypto-LA kits for detecting Cryptococcus neoformans capsular polysaccharide antigens were evaluated. Ten kits proved reliable for detecting and titering antigen in clinical materials. Fourteen kits were found to be inadequate.     

Comparison of a Reversed Passive Latex Agglutination and a Polymerase Chain Reaction for Identification of Cholera Toxin Producing Vibrio cholerae O1

Production of cholera toxin (CT) in AKI medium and conservation of CT gene (ctx) of 49 strains of Vibrio cholerae O1 were compared by reversed passive latex agglutination (RPLA) and polymerase chain reaction (PCR). The production of CT agreed with conservation of the ctx in 48 out of the 49 strains. Ten strains were positive, and 38 strains were negative by both methods. Only one strain was negative in RPLA and positive in PCR. This suggested that the combination of AKI-SW and RPLA is comparable to PCR to identify CT-producing V. cholerae O1.