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Sensitivity and specificity of the agar-gel-immunodiffusion test, ELISA and the skin test for detection of paratuberculosis in United States Midwest sheep populations.

Our objective was to estimate the sensitivity and specificity of the agar-gel-immunodiffusion test (AGID), the ELISA, and the skin test for the detection of Mycobacterium avium subspecies paratuberculosis (MAP) in sheep using Bayesian methods without a gold standard. Fourteen flocks (2 465 sheep) were used. Five flocks (450 sheep) were considered MAP non-infected and 9 flocks (2 015 sheep) had sheep infected with MAP. Sheep were skin tested and blood was collected for AGID and ELISA testing. Results were analyzed using a Bayesian 3-test in 1-population model fitted in WinBUGS. The model allowed for dependence (correlation) between the two serologic tests, but these two tests were assumed to be conditionally independent of the skin test. The estimated specificity was 99.5% (95% PI of 98.9-99.9%) for the AGID; 99.3% (98.4-99.8%) for the ELISA using an optical density measured cutoff of 0.20; 99.2% (98.1-99.8%) using a cutoff of 0.15; 97.5% (95.8-98.7%) using a cutoff of 0.10; and 98.7% (97.3-99.5%) for the skin test. The estimated sensitivities were 8.3% (6.2-10.7%) for the AGID; 8.0% (6.0-10.4%), 10.6% (8.3-13.1%), and 16.3% (13.5-19.4%) for the ELISA using the cutoffs 0.20, 0.15, and 0.10 respectively; and 73.3% (62.3-85.8%) for the skin test. The skin test was specific in non-infected populations and sensitive in infected populations, although in some cases a positive skin test might represent MAP exposure rather than infection. The AGID and ELISA were specific but lacked sensitivity. The AGID and ELISA consistently identified two different populations of infected sheep with only moderate overlap between positive test results.

Animals↗

Mold testing by RAST and skin test methods in patients with allergic fungal sinusitis.

RAST tests have traditionally been considered less sensitive than skin tests during investigation of atopy involving molds. This has been attributed to technical problems such as difficulty in binding the mold antigen to the carrier substrate. Ten patients with proven allergic fungal sinusitis were evaluated for sensitivity to 11 important molds by both RAST and dilutional intradermal testing. A predictable correlation between RAST and skin test scores was observed in many, but not all, cases. Most often this disparity was in the form of greater sensitivity indicated by skin testing than by RAST, sometimes differing by as many as 3 classes. The lack of concordance was not confined to testing for the fungi cultured from the sinuses, nor was it more or less pronounced in the case of dematiaceous fungi. The most likely causes for the disparity noted in this series are subtle differences in antigens used in skin test material and for RAST standards. Skin tests allow for evaluation of delayed and late-phase reactions, a measurement not possible by specific IgE testing with RAST. Delayed skin test reactions were not noted in this series of patients. An additional important finding was the sensitivity of patients with allergic fungal sinusitis to virtually every fungal antigen to which they were tested.

Allergens↗

Comparison of the Quintest to the lancet in allergic skin testing.

Many skin testing devices have been commercially available over recent years, but use has been limited because of significantly greater costs of such devices. Therefore, the lancet continues to be the most widely used skin testing device in Australia. This study compared performance of another multitest device, the Bayer Quintest to the Becton Dickinson Microlance. Nineteen atopic volunteers were skin tested using histamine dihydrochloride 10 mg/ml, glycerosaline and eight allergens. In 190 tests, 6 discrepancies between the Quintest and Microlance occurred. The Microlance produced slightly larger wheals than the Quintest, reaching statistical significance in 3 allergens. We found the Quintest comparable to the Microlance in concordance of positive and negative allergen responses and in wheal size. The Quintest had higher acceptability to both participants and staff for comfort, ease of use and safety. The Quintest's major advantage is the ability to rapidly screen large numbers of subjects, especially during clinical trials. The major limitation is it's cost.

Adult↗

Automated histamine analysis for in vitro allergy testing. II. Correlation of skin test results with in vitro whole blood histamine release in 82 patients.

The recently developed sensitive, automated histamine assay system was applied for in vitro allergy testing. The simplified method for histamine release from whole heparinized blood was used. Aliquots of blood and allergen were incubated for one hour at 37 degrees C, and each supernatant was then analyzed for histamine release. Nine common pollen and environmental allergens were used at three 10-fold dilutions for in vitro testing with the use of 20 ml of blood. Intradermal skin tests were correlated with the whole blood histamine release in 82 patients who had received no immunotherapy. A scoring system for the histamine results was developed to take into consideration the results with multiple allergen concentrations. When the skin test was strongly positive (greater than or equal to 3 + at 100 protein nitrogen units [PNU]/ml), the whole blood histamine release was positive in 89% of the tests. In contrast, when the skin test was negative ( less than 1 + at 100 PNU/ml), the histamine release was also negative in 99.8% of the cases. When the skin test was 1 +, the histamine release from whole blood was positive in 6% of the tests; and when the skin test was 2+, the whole blood results were positive in 32%. The accuracy, precision, and sensitivity of the automated histamine assay allow its application for the clinical study of allergic patients.

Allergens↗

Value of food antigen specific IgE-RAST and immediate reaction skin test.

Puncture skin tests with crude food extracts correlate well with proved IgE-mediated food allergy. The RAST may be effective in the diagnosis of IgE-mediated food hypersensitivity when purified allergens are used and when crude food extracts are used. A positive RAST to a food may demonstrate IgE antibody directed to that food but not necessarily implies clinical sensitivity. The RAST may not be efficacious for diagnosing in food allergy if the total IgE value is greatly elevated.

Child↗

Atopic skin test re-evaulated. IV. The use of compound 48/80 in routine skin testing.

Analysis of skin-test results obtained with compound 48/80 has indicated that this substance deserves a place in the standard series of test fluids for routine skin testing. No influence of sex or season was detected but there were significant differences in response related to the age (strongest reactions in the 16-40 year age group) and to the diagnosis (strongest reactions in the atopic patients).

Adolescent↗

Variables in allergy skin testing.

Allergy skin testing for immediate hypersensitivity is affected by a number of factors, some under the control of and others not controllable by the operator. Uncontrollable factors include the patient's age, chronobiological variation, and variation in reactivity between different parts of the body. Controllable factors include medications the patient is using, the quality of the allergy extract employed, the distance between test sites, the choice of prick or intradermal technique, and in the case of percutaneous testing, the device that is used. Considering the importance of the information that is generated by skin testing, and the major therapeutic commitments often resulting, more attention should be given to the techniques employed. It is suggested that operator performance can and should be assessed by relatively simple tests.

Administration, Cutaneous↗

Skin testing with penicilloate and penilloate prepared by an improved method: amoxicillin oral challenge in patients with negative skin test responses to penicillin reagents.

BACKGROUND: Penicillin skin testing has been limited by the lack of commercially available penicilloate and penilloate reagents. OBJECTIVE: This project was proposed to produce a stable, well-characterized supply of penicilloate and penilloate for intrastate use by our health maintenance organization and to document clinical safety and efficacy. METHODS: An improved method of extraction for penicilloate and penilloate, which changed the solvents used during recrystallization, was developed. With these newly prepared reagents, penicillin skin testing was performed on 348 subjects. Skin testing was immediately followed by an oral challenge of 250 mg of amoxicillin in 215 of 288 (75%) subjects displaying a negative response to a battery of penicillin skin tests. RESULTS: Nuclear magnetic resonance and mass spectrometry of the newly produced penicilloate and penilloate showed no evidence of organic contamination. Penicillin skin testing resulted in 17.2% (60 of 348) positive test results, with 20% of the subjects with positive results only responding to the newly produced minor determinants. The rate of mild adverse reactions to penicillin skin testing was 1.1% (4 of 348). The rate of mild acute adverse reactions was 5.1% (11 of 215), and the delayed reaction rate was 0.9% (2 of 215) with the amoxicillin challenge. CONCLUSIONS: This improved penicillin minor determinant extraction method allows for the reproducible production of very pure preparations of penicilloate and penilloate. Large-scale penicillin skin testing, followed by amoxicillin challenge if results are negative is feasible in a large group model health maintenance organization operating within a single state with the use of internally produced penicilloate and penilloate and commercially available penicillin, amoxicillin, and penicilloyl polylysine.

Administration, Oral↗

Tuberculin skin test results and the booster phenomenon in two-step tuberculin skin testing in hemodialysis patients.

Patients with chronic renal failure are at increased risk for tuberculosis (TB). Centers for Disease Control and Prevention (CDC) have recommended annual skin testing for TB, with tuberculin-purified protein derivative (PPD), in patients with chronic renal failure. Uremia alters the macrophage function, which can lead to anergy for skin tests. The aim of this prospective study was to determine the prevalence of positive tuberculin skin test (TST) and the booster effect of TST in hemodialysis patients living in a relatively underdeveloped portion of the country. Material and Methods. Patients were recruited from Van (Yuzuncu Yil University Hospital, Yuksek Ihtisas Hospital) and the Mus State Hospital). At the time of this study, a total of 143 patients were under hemodialysis treatment in these hemodialysis centers, and among them, 124 were included in the study. Informed consent was obtained before inclusion in the study. A positive PPD was an induration of >10 mm in response to five tuberculin units of PPD (RT23-Tween 80), at 72 h. TST-negative patients received a booster TST 10 days later, approximately 10 cm away from the previous intracutaneous injection. The test dose could not be increased due to unavailability of this kind of preparation. The test was performed and interpreted in the same way. Skin testing was performed in June and December 2003. Patients with known active TB are not included in the study. Testing was not done in hospitalized patients to rule out effects of other disease states. Results. Mean age of the patients was 45.3 +/- 16 (range 13-82) years. All patients were on HD treatment twice (n: 14) or three times (n: 110) weekly. Duration of dialysis before TST was 30 +/- 17 (12-84) months. With the first test (n: 14), 11.3% of the patients showed a positive reaction; the second test added (n: 15) 12.1% more TST-positive patients, reaching a total of (n: 29) 23.4% of the patients with a positive TST. The

Age Distribution↗

Skin tests and histamine release with P1-depleted Dermatophagoides pteronyssinus body extracts and purified P1.

Monoclonal antibodies were raised against P1 and Dp X, two major allergens in Dermatophagoides pteronyssinus extracts. The concentrations of IgE antibodies to P1 and Dp X in sera of mite-sensitive patients were determined in RAST with immunosorbent-bound monoclonal antibodies used for insolubilization of the allergens. The major allergen-specific IgE titers were compared with the total IgE response against D. pteronyssinus. The results of these serologic assays confirmed studies in the literature that P1 and Dp X are major allergens. The contribution of IgE anti-P1 to the total antimite response frequently exceeded 50% and, in general, appeared to be higher than the contribution of IgE anti-Dp X. Twenty percent of the mite-sensitive patients had no detectable IgE to either P1 or Dp X. The contribution of P1 to the biologic activity of D. pteronyssinus body extracts was derived from the effect of P1 depletion on the reactivity in the histamine-release test and skin test. This technique was preferred to the study of purified allergen because biologic activity of the nonabsorbed components is not affected. Immunization of rabbits with affinity-purified P1 yielded monospecific polyclonal antisera. Mite extracts depleted with either monoclonal or polyclonal anti-P1 were applied in the histamine-release test. The skin test was performed with extracts depleted with polyclonal anti-P1. In addition, the activity of affinity-purified P1 was investigated in these tests. The results indicated that P1 depletion of D. pteronyssinus body extracts had no detectable effect on the activity in most patients, namely, at least 70% of the activity was retained in the depleted extract. There was a considerable variation between patients in the sensitivity for purified P1, as compared to the sensitivity for whole D. pteronyssinus extracts. In the histamine-release test, the activity of purified P1 was up to 35% of the activity of the D. pteronyssinus body extract but did not exceed 10% in most patients. This was in agreement with the relative activity of purified P1, as found in the skin test. Therefore, the contribution of P1 to the biologic activity of D. pteronyssinus body extracts, as measured by end point titration, appeared to be less than expected on the basis of the serologic studies and articles in literature. The depletion experiments stress that there is still much uncertainty as to the biologic activity of house dust-mite extracts.

Adolescent↗

Results of the National Institute of Allergy and Infectious Diseases Collaborative Clinical Trial to test the predictive value of skin testing with major and minor penicillin derivatives in hospitalized adults.

BACKGROUND: A history (or lack thereof) of penicillin allergy is known to be unreliable in predicting reactions on subsequent administration of the drug. This study tests the usefulness of four penicillin allergen skin tests in the prediction of IgE-mediated reactions subsequent to administration of penicillin. METHODS: Eight centers cooperated in the National Institute of Allergy and Infectious Diseases trial of the predictive value of skin testing with major and minor penicillin derivatives. Hospitalized adults were tested with a major determinant (octa-benzylpenicilloyl-ocytalysine) and a minor determinant mixture and its components (potassium benzylpenicillin, benzylpenicilloate, and benzylpenicilloyl-N-propylamine). Patients then received a therapeutic course of penicillin and were observed, for 48 hours, for adverse reactions compatible with an IgE-mediated immediate or accelerated allergy. RESULTS: Among 726 history-positive patients, 566 with negative skin tests received penicillin and only seven (1.2%) had possibly IgE-mediated reactions. Among 600 history-negative patients, 568 with negative skin tests received penicillin and none had a reaction. Only nine of the 167 positive skin test reactors received a penicillin agent and then usually by cautious incremental dosing. Two (22%) of these nine patients had reactions compatible with IgE-mediated immediate or accelerated penicillin allergy; both were positive to the two determinants. CONCLUSIONS: These data corroborate previous data about the negative predictive value of negative skin tests to these materials. The reaction rate in skin test-positive patients was significantly higher than in those with negative skin tests, demonstrating the positive predictive value of positive tests to both major and minor determinants. The number of patients positive only to the major determinant or only to the minor determinant mix was too small to draw conclusions about the positive predictive value of either reagent alone.

Adult↗

A practical method for the production of Brucella skin test antigen.

Skin test antigens for the diagnosis of brucellosis were produced from the rough Brucella abortus strain 45/20. The production of two products termed Brucellin B and Brucellin W are described. The method described for the production of Brucellin W is recommended as an improved practical method of Brucellin production. The Brucellin products described were equal in sensitivity to that of a commercially available product, Brucellergen, which is used in New Zealand. Brucellin B was extensively tested in non-infected cattle and its specificity was equal to that of Brucellergen. Recommendations for the standardisation of skin test reagents for the diagnosis of brucellosis are made. Intradermal testing for brucellosis in cattle should be used only for the identification of infected herds and not as an individual animal test.

Journal Article↗