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Results for “False Negative Reactions”

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At least 19 recordsLinked to original sources
PubMed1978

[Antibody monstration in blastomyces infections].

The evidence of humoral antibodies against yeasts can be a valuable help in the diagnosis of such infections. It is however necessary to use several sensitive methods, which complete one another in the detection of the different immunoglobulins. In the interpretation of the results the titer dynamic is decisive, especially in those patients whose antibody answer is suppressed by their disease and/or their therapeutic treatment. In most of the yeast infections Candida albicans can be used as antigen for the detection of antibodies because there is a strong relationship between the antigens of most of the yeasts important in human infections. C. krusei, C. pseudotropicalis and C. guilliermondii do not display enough common antigens to make a diagnosis against these yeasts possible with C. albicans. In that case homologous antigens have to be used. Cross reactions with other microorganisms are less frequent than usually supposed. Therefore so called false positive Candida titers have to be examined very carefully by clinical signs and culture methods.

Antibodies, Fungal↗
PubMed1977

Comparison of methods for rapid immunofluroescent staining of group A streptococci and Neisseria gonorrhoeae.

Immunofluorescent staining reactions for group A streptococci and Neisseria gonorrhoeae were equivalent to those of standard "slow" methods when slides were heated on a serological water bath at 50 C for periods one to four minutes. No false negative reactions occurred when this method was used. False negative reactions occasionally occurred when previously described rapid methods which employed a slide warmer were used.

Fluorescent Antibody Technique↗
PubMed1975

Use of immunoperoxidase on brain tissue for the rapid diagnosis of herpes encephalitis.

An indirect immunoperoxidase method to detect herpes simplex viral antigen in brain cell suspensions from patients suspected to have herpes encephalitis is described. The method is rapid, reliable and specific, and successfully identified the herpes virus infected cells in four of five culture-proven cases. There was one false-negative reaction, but no false-positive. The immunoperoxidase technic offers a number of advantages over immunofluorescence for routine diagnosis.

Antigens, Viral↗
PubMed1978

Experiences with radioimmunoassay in the detection of HBsAg in the presence of anti-HBs.

Interference from anti-HBs present during hepatitis B antigenemia caused the appearance of several false negative reactions in a competition radioimmuno-precipitation procedure. The results indicate that such interference is considerably less in the solid-phase radioimmunoassay (Ausria II) and probably causes few false negative tests. The use of pepsin treatment as a means to destroy interfering antibodies is discussed.

Antibodies, Viral↗
PubMed1975

Severe histamine mediated reactions to intravenous drugs used in anaesthesia.

Severe histamine mediated reactions to intravenous drugs used in anaesthesia may occur as a result of anaphylactic and anaphylactoid reactions. The incidence is rare, but appears to be increasing. The difficulties in diagnosing such reactions and in determining the drug responsible and how these difficulties have led to confusion in the literature are discussed. Six cases of severe histamine mediated reactions are presented and detailed analyses of the drugs in these and other reported reactions is made showing varied clinical patterns with different drugs. The prevention, treatment, and follow-up of severe histamine mediated reactions are considered.

Adolescent↗
PubMedDate not supplied

Autoimmune hemolytic anemia associated exclusively with IgA of Rh specificity.

A nine-year-old boy had typical clinical, hematologic and blood group serologic findings of autoimmune hemolytic anemia except for one important exception; with most commercially available broad spectrum anti-human sera the direct antiglobulin tests were negative. With reagents prepared in the laboratory which were found to be relatively less potent in and anti-IgG and IgM activity but which utilize a short period of incubation after mixing with the washed cells, the tests were all clearly positive. If incubation were employed with the commercial reagents, the tests were positive. Further studies showed that the patient's cells were coated exclusively with IgA and that a commercial reagent, although potent in anti-IgG and anti-IgM, was relatively deficient in anti-IgA. It is proposed that incubation compensates for the latter and is cautioned that incubation, with reagents potent in anti-IgG, could lead to false negative reactions with weakly IgG sensitized cells due to antibody surplus prozones of inhibition. This case illustrates that the rare instances of "Coombs negative immune hemolytic anemias" may be based on mechanisms such as those reported here and, that to be ideal, a broad spectrum anti-human serum should have balanced anti-immunoglobulin activities in relation to its incubation time.

Anemia, Hemolytic, Autoimmune↗
PubMed1979

Antigenic components of Taenia saginata and their relevance to the diagnosis of bovine cysticercosis by immunoelectrophoresis.

22 antigenic components of Taenia saginata proglottides were detected by immunoelectrophoretic (IEP) study. Cross-absorption of the hyperimmune serum, raised in rabbits against T. saginata, with heterologous and host antigens showed that two thirds of these components were not specific for the cestode. Among the calves experimentally infected with T. saginata eggs, 3 precipitation patterns in IEP were identified depending on the evolutionary stage of the infection. The hydrosoluble extract of T. saginata was used as antigen. A short precipitating arc present near the antigen well and appearing 3 to 4 weeks post-infection of the calves and a long precipitating arc extending towards the anodic end of the slide and appearing in later stages of infection were found of high diagnostic value. No false-positive reaction or cross-reaction were found. Among the calves harbouring less than 50 cysticerci, false-negative reactions were seen.

Animals↗
PubMed1978

Complement fixation antibody test for human nocardiosis.

Complement-fixing antibody was detected in 13 of 16 patients with histological and/or culture evidence of infection with Nocardia species. The antigen used was a filtrate of soluble substances secreted into liquid growth medium by cultures of N. asteroides. Apparent false positives reactions were found in three of three patients with leprosy and two of five patients with tuberculosis--results similar to some previously reported methods. N. asteroides and mycobacteria share antigens. Only the false positives with tuberculosis are considered a diagnostic problem. No reactions were obtained with sera from 26 patients with other infections and 41 unifected individuals. Whereas previous nocardia serodiagnostic methods have a sensitivity of approximately 50%, our overall sensitivity (81%) compares favorably and included 9 of 11 positive tests in immunocompromised nocardiosis patients (a source of false negative reactions with previous methods).

Adult↗
PubMed1976

[Lymphocyte transformation test in Gell's and Coombs' drug reactions].

A method of interpretation of the lymphocyte transformation test is described which results on the basis of statistical evaluation. With this method good results were received in cases of drug induced side effects of type I according to Gell and Coombs. The investigations on 61 patients have shown that differneces between the clinical findings and lymphocyte transformation tests are rare. They are mainly in relation to false-positive reactions of the lymphocyte transformation test in Penicillin allergy.

Diagnostic Errors↗
PubMed1978

Pitfalls in the diagnosis of pericardial effusion.

Echocardiography has proven to be a sensitive and reliable technique in the diagnosis of pericardial effusion. Care must be taken in recording to maintain proper angulation of the transducer, to scan adequate sites, and to maintain proper gain settings. The following entities may mimic pericardial effusion and must be excluded by careful analysis: left pleural effusion, mitral annulus calcification, anterior mediastinal space-occupying lesions, fibrinous pericardial reactions, and right heart catheters. Care must also be taken in the quantitation of pericardial fluid and in hemodynamic extrapolation.

Calcinosis↗
PubMed1977

Diagnosis of Hymenoptera hypersensitivity by skin testing with Hymenoptera venoms.

This double-blind study provides evidence that skin testing with dialyzed Hymenoptera venoms is a more accurate, reliable method of diagnosing hypersensitivity to the sting of honeybee, yellow jacket, yellow hornet, white-faced hornet, and wasp than is skin testing with the corresponding whole body diagnostic allergenic extract. Furthermore, the incidence of false-positives was greatly reduced by using the dialyzed Hymenoptera venom (HDV) diagnosis. In this clinical trial, most sensitive individuals had skin test reactions greater than the diluent control at concentrations of 1 mug/ml or below. Levels of venom diagnostic of 100 mug/ml appeared to produce nonspecific local irritation. Skin test with whole body diagnostic allergenic extract did not produce a consistent differentiation between sensitive and nonsensitive individuals. No untoward reactions were seen using the dialyzed Hymenoptera venom (HDV) diagnostic.

Animals↗
PubMed1978

[Applications and limitations of immunological techniques in the sero-epidemiological analysis of parasitic risk (author's transl)].

In order to be applicable to sero-epidemiology, serological reactions must lend themselves to micro-techniques and automation. Their results, notably concerning malaria, sleeping sickness, amoebiasis, schistosomiasis and filariasis, complement those of direct parasitological examination. Serology is often more accurate, but is also more costly and should be reserved for those cases in which other analytical methods are either impossible or too undependable (low transmission level). Serological methods generally involve little risk or false negativity, but they can be falsely positive and improvement of the specificity of available testing procedures is at present one of the major technological problems of parasitic sero-epidemiology.

Amebiasis↗
PubMed1977

Characterisation of immunofluorescent heterophile antibodies which may be confused with autoantibodies.

Approximately 6% of sera submitted for routine immunofluorescent autoantibody screeening produced characteristic reaction patterns against a variety of animal and human tissues. It is suggested that these non-tissue-specific patterns represent a complex family of heterophile antibodies which could be confused with certain autoantibodies. It is further suggested that these heterophile antibodies bear a relationship to IgG isohaemagglutinins.

Animals↗
PubMed1977

[Diagnostic significance of identification of anti-entamoeba histolytica antibodies (author's transl)].

Examinations were performed with the indirect immunofluorescence test (IFAT) and the indirect haemagglutination test (IHAT). Negative titers (less than 1:5) do not exclude an infection with E. histolytica. Titers up to 1:80 in both reactions are found in patients with negative stool specimens or indicate an asymptomatic infection of the intestinal lumen, an incipient or past symptomatic amoebiasis. IFAT values of 1:160 together with a negative or positive IHAT are also suggestive of the two last-mentioned types of infection. These titers are also found in patients with gastrointestinal disorders of other orgin. IFAT values higher than 1:60 with a positive IHAT are probably due to an invasive amoebiasis. Titres are, however, only diagnostic pointers.

Amebiasis↗
PubMed1975

[How effective are tests for avoiding contrast reactions].

The frequency of known severe and fatal reactions after intravenous injections of biligrafin forte were compared during two periods. During the first period test ampules were provided; during the second period, the test ampules were no longer made. It was shown that the failure to perform tests did not result in any increase in the complication rate when compared with the period when test ampules were available. The problems arising from this comparison are discussed.

Biliary Tract Diseases↗
PubMed1978

Comparison of miniaturized multitest systems with conventional methodology for identification of Enterobacteriaceae from foods.

Four miniaturized multiple test systems were compared with tube methodology used to identify Enterobacteriaceae encountered in foods. Identification aids supplied with each system were used to assign names to isolates at the species level. For the 129 strains tested, the Minitek system demonstrated a 96.9 percent agreement with reactions in tubed media. The Inolex, Analytab, and PathoTec test systems exhibited 94.3, 93.8, and 92.7 percent agreement, respectively. Analytab identified 96.1 percent of the isolates to the species level, whereas the Minitek, PathoTec, and Inolex systems were able to identify 78.3, 32.6, and 27.1 percent, respectively. The results indicate that the Analytab and Minitek systems are acceptable substitutes for the tube methodology routinely employed in identifying enterics from foods. Although the PathoTec system might be used to screen isolates for their identity, neither the presently available PathoTec nor the Inolex systems should be substituted for current methodology when definitive identification of foodborne organisms is required.

Bacteriological Techniques↗
PubMed1978

[Passive haemagglutination test in serodiagnosis of syphilis. Survey of a one-year trial in a venereal diseases prophylactic center (author's transl)].

We report here a one-year study of the reliability of the Treponema pallidum Haemagglutination Test (TPHA) in the serological diagnosis of syphilis. By comparing TPHA data with the diagnosis based on a set of grouped criteria, we were able to determine TPHA accuracy. All studies were conducted at the Antivenereal Prophylactic Center, in Nice, France, on 1,775 sera. The grouped data consisted of:--Serological Test for Syphilis (STS) using cardiolipin antigen,--medical and epidemiological records;--two specific reactions; namely the Fluorescent Antibody Test (FTA) and the Treponema Immobilisation Test (TIT). Reliability is excellent in 98.58 p. 100: the TPHA either proves syphilis or eliminates this diagnosis. The TPHA was particularly useful in investigating "problem sera" for which there existed conflicts in the grouped data. The applicability of TPHA is limited, however, in that it has low sensitivity during early primary syphilis, and it cannot be used to monitor antibodies during treatment. Nevertheless, TPHA, based on a standard specific antigen, is assured of a high place among the tools of serological diagnosis of syphilis because of its high accuracy and sensitivity, its objective and easily read results, and the simplicity of its technique.

False Negative Reactions↗