Possibilities of enhancing the sensitivity of the coagglutination reaction

The influence of heating Shigella suspension at 60 degrees C (for 3 minutes) and 100 degrees C (for 30 minutes), as well as adding extraneous microorganisms (Escherichia coli, Proteus) and homologous antibodies to these suspensions, on the sensitivity of the coagglutination test has been studied. The possibility of enhancing the sensitivity of this test 10 to 100 times by heating Shigella suspensions at 100 degrees C for 30 minutes has been shown.     

Identification of Salmonella enterotoxin by coagglutination reaction

It has been shown that the intensity of enterotoxin production by various strains of Salmonella is different (it ranges from + to +). Thus, in addition to adhesive properties and skin permeability factors, the ability of various Salmonella strains to produce enterotoxin is one of the pathogenic factors of these microorganisms. Further biological characteristics of the infective agents will promote the detection of epidemiologically significant types of microorganisms during outbreaks of toxicoinfections.     

Use of the coagglutination reaction for identifying Shigella flexneri

The data on the use of the coagglutination test for the identification of Sh. flexneri are presented. The influence of different methods for the treatment of antisera on their heterologous reactions was studied and the advantage of coagglutinating reagents was revealed. 9 variants of coagglutinating preparations were obtained; their use made it possible to reduce the consumption of antisera and in some cases avoid their absorption. The problem of Sh. flexneri classification is discussed.     

Serum chromogranin-alpha immunoradiometric assay in the diagnosis of pheochromocytoma

BACKGROUND: The diagnosis of pheochromocytoma is based on laboratory tests that demonstrate an increase in urinary excretion of catecholamines or their metabolites. Chromogranin A (CgA) is a member of the granin family and is widely distributed in neuroendocrine cells and particularly in chromaffin adrenal cells. Consequently, serum CgA increases in patients affected by pheochromocytoma and other diseases of the chromaffin system. AIM: This study investigated the performance of serum CgA assay in the diagnosis of pheochromocytoma and compared serum CgA with 24-hour urinary epinephrine (E), norepinephrine (NE), vanillylmandelic acid (VMA) and metanephrines (MNs). METHODS: We enrolled 15 patients with histologically proven pheochromocytoma; 100 healthy blood donors and 148 patients with essential hypertension were enrolled as controls. Serum CgA was assayed by a specific immunoradiometric method (IRMA). Urinary tests were done with high performance liquid chromatography (HPLC). RESULTS: Circulating CgA showed a higher sensitivity (1.00), specificity (0.96) and accuracy (0.96) than all other tests. Serum levels of CgA clearly increased from blood donors and patients with essential hypertension to patients with pheochromocytoma (p<0.0001). Furthermore, a strong relationship between serum CgA and tumor mass was found (p<0.0001). In conclusion, our data suggest that the CgA assay might be used as a single test for the diagnosis of pheochromocytoma.     

Diagnostic significance of the coagglutination reaction in patients with the diarrhoea syndrome

Specific soluble Shigella, Salmonella and Yersinia enterocolitica antigens were determined in biological fluids (saliva, urine, coprofiltrate) from 268 patients with the diarrhoea syndrome using the coagglutination reaction. The findings suggest that the coagglutination reaction (COA) is a simple and efficient method suitable for the fast diagnosing of acute intestinal infection (AII) in the early days from the onset of the disease. COA enables the identification of specific antigens associated with the causative agents of intestinal infections in 79-54% of patients with shigellosis and salmonellosis. COA was shown to possess a high diagnostic potential in AII of unknown etiology. Shigella, Salmonella and Yersinia antigens were determined in 47.7, 23.4 and 10.8% of cases respectively where no bacterial excretion could be confirmed. Two and less frequently three antigens being identified simultaneously in 10.8% cases. The identification of opportunistic microorganisms in AII using the COA does not appear to be sufficient to confirm their etiological significance as Shigella and Salmonella antigens were simultaneously determined in most patients.     

The rapid diagnosis of salmonellosis by a determination of the antigen in the biosubstrates of patients using the coagglutination reaction]

The diagnostic potential of the coagglutination test was checked with the aim of improving the laboratory diagnosis of Salmonella infections by the detection of Salmonella specific antigen in different biological materials (feces, urine, saliva and immune complexes in blood sera). The study of all specimens resulted in the confirmation of the diagnosis in 78% of patients, often during the first days of the disease. The proportion of nonspecific reactions, as shown in the control groups of healthy donors and patients with dysentery and other acute enteric infections, did not exceed 5%.     

Determination of O and Vi antigens in typhoid fever in the slide coagglutination reaction

Investigations with a view to the development and trial of a slide coagglutination test system for the detection of specific Salmonella typhi antigens have been made. As a result, diagnostic agents with sensitivity to group D Salmonella lipopolysaccharides and Vi-antigen, equal to 1 X 10(-5) to 1 X 10(-6) g/l, have been obtained. Specimens of saliva, urine and fecal filtrates from 61 adult patients with bacteriologically confirmed typhoid fever and 54 practically healthy persons have been studied. The coagglutination test has been positive with specimens from 90 +/- 4% of typhoid fever patients and, within the first 5 days of the disease, with those from 85 +/- 7% of such patients. The slide coagglutination test with saliva specimens has been found to be more informative than that with urine specimens. The data obtained in these investigations indicate that the slide coagglutination test is highly sensitive and specific, which offers good prospects for its use as a simple, economic and demonstrative method for the early tentative diagnosis of typhoid fever.     

Use of a method of immunoradiometric analysis for detecting the persistence of Rickettsiae and their antigens in an experimental infection in cotton rats

An indirect modification of the radioimmunoassay (RIA) was shown to be highly sensitive in the determination of the minimal amounts of R. prowazekii and their antigens in the organs and tissues of infected animals. RIA proved to be effective in the determination of the antigens in the blood in cases of R. prowazekii persistence in infected animals. The data obtained in these investigations point to good prospects for using RIA in the study of persistence of microorganisms and their antigens.     

Evaluation of an improved rapid coagglutination method for the serological grouping of beta-hemolytic streptococci.

Grouping of beta-hemolytic streptococci was performed with the Phadebact Streptococcus Test, a coagglutination method, and the results compared with serological grouping by the standard Lancefield precipitin method. Of 171 clinical specimens examined, 169 (98.8%) were grouped correctly by the Phadebact Test after 24 h of continuous growth in Todd-Hewitt broth. In a parallel study, 96.9% of specimens that grew after only 4 h of incubation in broth were grouped correctly by the coagglutination method. In both studies, the accuracy of the coagglutination test was increased significantly by elimination of multiple-agglutination reactions through centrifugation of cultures and utilization of the supernatant fluid in the Phadebact Test.     

Immunoenzyme analysis and polymerase chain reaction in the diagnosis of an intrauterine infection in newborn infants with cerebral lesions

The comparative evaluation of the diagnostic value of the polymerase chain reaction (PCR) and the enzyme immunoassay (EIA) in the detection of intrauterine infection (IUI) in 48 newborn infants with cerebral lesions was made. Tests for the presence of the infective agents of IUI, most frequently occurring in the region (Cytomegalovirus, Herpes simplex virus, Chlamydia trachomatis), were carried out. The levels of serum IgA, IgG and IgM were evaluated in the course of the primary screening of IUI. Laboratory samples for PCR from infants with IUI were selected at random. The study demonstrated that in PCR the frequency of positive results was significantly greater than in EIA.     

The polymerase chain reaction: an improved method for the analysis of nucleic acids

Summary The polymerase chain reaction (PCR) is a method for the selective amplification of DNA or RNA segments of up to 2 kilobasepairs (kb) or more in length. Synthetic oligonucleotides flanking sequences of interest are used in repeated cycles of enzymatic primer extension in opposite and overlapping directions. The essential steps in each cycle are thermal denaturation of double-stranded target molecules, primer annealing to both strands and enzymatic synthesis of DNA. The use of the heat-stable DNA polymerase from the archebacterium Thermus aquaticus (Taq polymerase) makes the reaction amenable to automation. Since both strands of a given DNA segment are used as templates, the number of target sequences increases exponentially. The reaction is simple, fast and extremely sensitive. The DNA or RNA content of a single cell is sufficient to detect a specific sequence. This method greatly facilitates the diagnosis of mutations or sequence polymorhisms of various types in human genetics, and the detection of pathogenic components and conditions in the context of clinical research and diagnostics; it is also useful in simplifying complex analytical or synthetic protocols in basic molecular biology. This article describes the principles of the reaction and discusses the applications in different areas of biomedical research.     

Use of the coagglutination reaction of yeast-like Candida maltosa fungi for detecting fimbriae in intestinal bacteria

The capacity of nonpathogenic yeast-like C. maltosa strains to coagglutinate Escherichia coli has been studied. C. maltosa cells have also been shown to coagglutinate E. coli possessing mannose-sensitive adhesins in a wide range of their concentrations (5-140 bacterial cells per C. maltosa cell). Strains belonging to types CFA/I and CFA/II with fimbriae, similarly to their corresponding paired genetically related strains without these adhesins, are practically incapable of agglutinating C. maltosa cells, while strains K88 and B41 react with them. The reaction occurs at a concentration of 9.5-37.0 and 38.0-55.5 bacteria respectively per C. maltosa cell and is not inhibited by 1% d-mannose. The suggestion that C. maltosa cell surface glycoproteins contain not only receptors for E. coli fimbriae, type I, but also components similar in their structure to receptors specific to the mannose-resistant adhesins of strains K88, K99 and 41, has been confirmed by hemagglutination inhibition with C. maltosa surface antigens as inhibiting agents.     

A rapid method of grouping beta-hemolytic streptococci using extemporaneous coagglutination

Extemporaneous coagglutination procedure for the serological grouping of beta-hemolytic streptococci is reported. Streptococcal group antigens were extracted with nitrous acid. 250 strains of groups A, B, C, F and G streptococci were tested with this method. An agreement of 100% was found between this method and the Lancefield capillary precipitation procedure. Extemporaneous coagglutination method was found to be rapid, reliable, easy and economical and could be adopted in any routine diagnostic laboratory.     

Patterns in the spread and serovirological diagnosis of serous meningitis

The epidemiological and clinico-etiological study of cases of acute serous meningitis with unknown etiology in children was carried out in a large industrial city at the period of a considerable morbidity rise caused by this infection. The maximum morbidity was registered among younger children under school age attending children's institutions. In 26 closed groups of children group morbidity was revealed (4 cases and more), in 5 such groups small local outbreaks were registered. The clinico-instrumental methods of study permitted one to differentiate the groups of children having serous meningitis of supposedly enteroviral etiology, and sero virological studies carried out with the use of a wide range of diagnostic reagents revealed the etiological role of group B Coxsackie virus, mainly type 4, in 20.6% of cases, ECHO virus, serotypes 3 and 11, in 20.7% of cases, and parotitis virus in 5.3% of cases.     

Detection of Shigella antigens in the feces of patients with acute intestinal diseases using a coagglutination reaction

A total of 113 patients with acute intestinal diseases have been examined with the use of the coagglutination test. 84.95% of the patients showed the presence of different Shigella antigens. In patients with bacteriologically confirmed dysentery the corresponding Shigella antigens were detected in 96.97% of cases in S. sonnei dysentery, in 90% of cases in S. flexneri dysentery, in 75% of cases in S. newcastle dysentery and in 100% of bases in S. boydii dysentery. In 81.6% of patients with acute intestinal diseases of unknown etiology the coagglutination test revealed the presence of various Shigella antigens.