Specificity and Sensitivity of the Streptozyme Test for the Detection of Streptococcal Antibodies

A comparison between the results of the streptozyme hemagglutination test and serological titers for anti-streptolysin O (ASO), anti-hyaluronidase (AH), anti-deoxyribonuclease B (ADN-B), and anti-nicotinamide adenine dinucleotidase (ANAD) was made in two groups of human sera. In one group, serological titers for all the four antibodies were lower than the threshold of sensitization reported by the producing firm. In the second group, the titer of at least one of the four antibodies was equal to or higher than the threshold. False-positive and false-negative reactions occur with those sera when one or more antibody titer is at or near the threshold of the test as described by the manufacturer. The test was positive for all sera where either the ASO was greater than 166 or the ANAD was greater than 270, and for 98% of the sera with ADN-B greater than 360. It is, therefore, concluded that the streptozyme test can be used as an adjunct to the clinical diagnosis of streptococcal infections and their nonsuppurative sequelae. It is less useful to assess the levels of antibodies in sera from general population surveys. For such sera, the relative specificity and sensitivity of the test might yield misleading results. Until more experience is gained with the test, caution should be used in its application to infant and older adult age groups, where significant streptococcal antibody titers are frequently near the threshold of the test.     

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.     

Comparison of Antistreptolysin O Latex Screening Test with the Antistreptolysin O Hemolytic Test

This report describes a comparison of the Behringwerke antistreptolysin O (ASO) latex screening test with the ASO hemolytic test. Agreement between the two tests was poor when Difco streptolysin O (SLO) reagent was employed in the hemolytic test; approximately 34% of the sera with ASO titers in the normal range of the hemolytic test gave false-positive latex test reactions. However, the percentage of false-positive latex test reactions was only 5% when Behringwerke SLO reagent was used in the hemolytic test. An assay of the Difco and Behringwerke SLO reagents against an ASO standard indicated that the Difco SLO reagent was more potent than the Behringwerke SLO reagent. The lack of agreement between the Behringwerke latex test and the hemolytic test using Difco SLO reagent is attributed to the potency of the SLO reagents.     

A preliminary evaluation of a new enzyme immunoassay to detect Chlamydia pneumoniae-specific antibodies

New enzyme immunoassays (EIAs) for determination of specific IgG, IgA, and IgM antibody titers to Chlamydia pneumoniae were evaluated independently in three research laboratories. Specificity of the EIAs was enhanced by removing LPS from the chlamydial antigen. The performance of these EIAs was evaluated in comparison with the microimmunofluorescence (MIF) test using specimens from: (i) a group of adult patients with community-acquired pneumonia (CAP) previously diagnosed as having an acute chlamydial infection by the complement fixation test or the whole inclusion fluorescence test; (ii) from a group of adult patients with acute respiratory tract infections; and (iii) from a group of young children consecutively presenting with acute respiratory tract infections. The MIF test and the EIAs detected acute infections in paired serum specimens from 12 of 14 patients from the first group. Eleven of these 12 patients were positive in both tests. The MIF test detected seven acute infections in single convalescence serum specimens from eight patients. Two of these were also positive in the EIAs. Paired serum specimens from the second group of adult patients (n=12) were collected during an epidemic of C. pneumoniae. The EIAs detected six acute infections. The MIF test detected two additional patients with acute infections. From the group of young children (n=30), the EIAs detected two patients with acute infections. Our conclusion from this preliminary evaluation is that these EIAs could be useful for laboratory diagnosis of acute C. pneumoniae infections. Comprehensive prospective studies should provide suitable data to calculate the sensitivity, specificity, and predictive values.     

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.     

“Upper Limits of Normal” Antistreptolysin O and Antideoxyribonuclease B Titers

"Upper limits of normal" antistreptolysin O (ASO) and antideoxyribonuclease (ADN) B titers were determined on serum specimens from various age groups of pediatric patients with no history of a recent streptococcal infection and on healthy adult hospital employees. The upper limit of normal value is that level of antibody titer exceeded by no more than 15% of the total subjects in each age group. This value varies with the age of the subject, and the most pronounced differences are between the values of preschool age children, school age children, and adults. The upper limit of normal values for these groups were as follows: preschool age, ASO = 85(100); ADN B = 60(50); school age, ASO = 170(166); ADN B=1 70(166); and adult, ASO = 85(100); ADN B = 85(100).     

Data on the push–out bond strength of three different root canal treatment sealers

It is of interest to document data on the push – out bond strength of three different root canal treatment sealers such as MTA Fillapex (MTA based), AH plus (Epoxy Resin based) and Apexit plus (Calcium hydroxide based). Forty-five freshly extracted human maxillary central incisors with closed apices were selected randomly. All the teeth were sectioned at cement-enamel junction using a diamond disc before starting the root canal preparation to obtain root length of 12 mm. All teeth were instrumented using ProTaper rotary instruments. 5.25% sodium hypochlorite was used for irrigation between instrumentation followed by 17% EDTA, and final rinse by saline. Obturation procedures were done using the gutta-percha single cone technique. 45 roots were randomly assigned to 3 groups of 15 for obturation with gutta-percha cones and 1 of the 3 sealers (n=15). Group 1 = MTA Fillapex sealer + gutta-percha: Group 2 = AH plus sealer + gutta-percha:Group 3 = Apexit plus sealer + gutta-percha. The roots were sectioned horizontally to its canal into 3 sections: Coronal, Mid-root and Apical-thirds using a precision cutting machine, with a thickness of 3 mm. The specimens were subjected to push-out test using a universal testing machine that carried a plunger. The loading speed was 1mm/min until the dislodgment of the material occurred. The independent t- test was used to compare the mean scores among the study groups. The level of significance was set at 5% for all tests. After the push-out bond strength test, each sample was evaluated under stereomicroscope (40x) to determine the mode of failure and recorded as one of the following categories: adhesive, cohesive or mixed. The observations thus obtained were subjected to statistical analysis using Student - t test. AH Plus showed significantly higher values than MTA Fillapex and Apexit plus (p < 0.05). Amongst the push-out bond strength AH Plus sealer showed significant difference from MTA Fillapex and Apexit plus groups. There was no significant difference between MTA Fillapex and Apexit plus however (p>0.05). Microscopic analysis displayed that the majority of the modes were cohesive failures for AH Plus, adhesive failures for MTA Fillapex and mixed failures for Apexit Plus. . Thus, AH Plus had the highest bond strength and MTA Fillapex had the lowest bond strength to root dentin. Mean push-out bond strength values were ranked as follows; AH Plus >Apexit Plus > MTA Fillapex. Microscopic analysis displayed that the majority of the modes were cohesive failures of AH Plus, adhesive failures for MTA Fillapex and mixed failures for Apexit Plus.     

Use of an indirect haemagglutination test for the detection of Clostridium perfringens type A enterotoxin.

An indirect haemagglutination (IH) test is described for the detection of Clostridium perfringens type A enterotoxin, produced by strains isolated from human cases of food poisoning and from contaminated food. Though no strict relationship could be observed between titers in the IH test and the time it took mice to die from the intravenous inoculation of mice (IIM test), results of the supernatants examined by both methods demonstrated that the IH test was more sensitive than the IIM one. No unspecific reaction was obtained in the IH with a negative control and the inhibitions of the IH and IIM tests by specific antiserum against C. perfringens enterotoxin showed that the IH test is very specific. The IH assay is recommended for its sensitivity and easy performance by less-equipped laboratories, by these and other data.     

High detection rates of cryptococcal antigen in pulmonary cryptococcosis by Eiken Latex Agglutination test with pronase pretreatment

Two different kits for the detection of serum cryptococcal antigen in patients with pulmonary cryptococcosis were evaluated. The Eiken test (the Eiken Co., Tokyo), which uses pronase for pretreatment of serum, was compared with the Crypto-LA test (International Biological Laboratories, Cranbury, NJ), which did not use pronase prior to testing. Cryptococcal antigen was detected in 21 of 23 patients (91%) with the Eiken test and in only 10 of 23 patients (43%) with the Crypto-LA test (p<0.01 by Mcnemar test). However, the sensitivity of two tests was identical without use of pronase, as both tests could detect as little as 10⁴ cells/ml ofCryptococcus neoformans and 10 ng/ml of capsular polysaccharide ofC. neoformans. In those serum specimens for which both tests were positive, titers were much higher for the Eiken test, but there was a statistically significant correlation between the two tests (coefficient correlation 0.79,p<0.01). Cryptococcal antigen titer levels measured by the Eiken test correlated well with clinical courses. There was one false-positive reaction among 82 sera of non-cryptococcal patients. Pronase enhanced the sensitivity of the Eiken test, which appeared to be useful in patients with pulmonary cryptococcal disease, and its use may prevent unneeded lung biopsies.     

Probing sequence variation in the receptor-targeting domain of feline leukemia virus envelope proteins with peptide display libraries

Determinants of cellular tropism and receptor targeting lie within a short peptide in the Vr1 region of the envelope (Env) proteins of feline leukemia virus (FeLV) subgroups A and C. Libraries of FeLV Env proteins with random amino acid substitutions in the peptide were screened for their ability to deliver a marker gene to D17 and AH927 cells. Screening on D17 canine cells yielded D17-specific Env proteins that used the FeLV-C receptor. Screening on AH927 cells yielded Env proteins with a broader host range, with maximal titers on AH927 cells and similar or lower titers on other cells. These Env proteins used an unidentified non-FeLV receptor for entry. The A5 isolate obtained from the AH927 screen was readily concentrated to yield titers of 10(5) on human PC-3 prostate tumor cells. The sequence divergence observed among targeting peptides of library-selected Env proteins was greater than that found in parental FeLV isolates. Substitution analyses of a conserved R in the middle of the targeting peptide held constant during screening indicated that maximal titers were obtained only when R was present in both a D17 selected isolate and an AH927 selected isolate. The ability to isolate Env proteins with unique tropisms dependent on the cells on which the library is screened has direct implications for targeting gene delivery vectors.     

Relationship between human sperm motility characteristics and sperm penetration into human cervical mucus in vitro

A series of 100 modified Kremer tests of human sperm penetration into human cervical mucus was carried out as part of the routine investigation of couples presenting with infertility. The outcome of these tests was significantly correlated with the concentration and progressive motility of the spermatozoa in the semen sample used for the test. Other semen characteristics significantly correlated with the test result were the mean velocity of progression (VP) and the amplitude of lateral head displacement about the axis of progression (AH) of the progressive spermatozoa. Normal sperm morphology was also correlated with the outcome. Using these semen characteristics as the independent variables to predict the test outcome in a discriminant analysis (normal vs abnormal tests), 34.2% of the variance was accounted for. From the discriminant function equation 75.0% of the test results could be predicted correctly. In the 30 cases in which the semen samples used for the tests showed greater than or equal to 25 X 10(6) progressively motile spermatozoa per ml, mean VP of greater than or equal to 25 microns/sec and mean AH of greater than or equal to 7.5 microns, 83.3% had normal test results. Conversely, all 13 cases for which the semen characteristics were below these limits had abnormal test results. Therefore, both the concentration of progressively motile spermatozoa and their movement characteristics are significant factors determining the outcome of homologous tests of human sperm-cervical mucus interaction.     

Comparison of 4 serological tests--complement fixation, neutralization, fluorescent antibody to membrane antigen and immune adherence hemagglutination--for assay of antibody to varicella-zoster (V-Z) virus.

Four tests for antibody to varicella-zoster (V-Z) virus were compared; these were tests of complement fixation (CF), neutralization (NT), fluorescent antibody to membrane antigen (FAMA) and immune adherence hemagglutination (IAHA). Fifty-two sera from patients with varicella and zoster and from recipients of live varicella vaccine were examined by the 4 tests. The CF test was least sensitive, but the antibody titers by the NT, FAMA and IAHA tests were roughly comparable. The IAHA test was the simplest and fastest to perform, and appeared suitable for routine serological assay to V-Z virus. The correlation between the IAHA antibody titer and susceptibility of individuals to clinical varicella was investigated retrospectively using sera obtained during 2 outbreaks of varicella in an institution for children, where all the unvaccinated children had developed varicella symptoms. Most of the 25 pre-exposure sera from unvaccinated children examined by the IAHA test had tiers of less than 1:2. In contrast, all the 23 sera from vaccinated children who did not develop varicella had detectable antibody titers of 1:2 to 1:64. These results indicate that the IAHA titer reflects the susceptibility or resistance of individuals to clinical varicella.     

Comparison of agar dilution test,broth dilution test,and broth elution test for assaying susceptibility ofCandida spp

Biochemically and morphologically defined isolates ofCandida spp. were tested for their susceptibility to systemic antimycotics (5-flucytosine, ketoconazole, and miconazole). Three different susceptibility test techniques—the broth disc elution test, the agar dilution test, and the broth dilution test—were examined. The different assays were correlated with the broth dilution test at breakpoint concentrations. Reliability and practicability of the test systems described here were good, and the agreement with the broth dilution test was excellent. The elution test seems to be a valuable method for smaller laboratories, whereas the agar dilution test with antimycotic tablets is a particularly and comparatively inexpensive test for laboratories handling larger numbers of specimens.     

类风湿关节炎患者抗CCP，RF，AKA，ASO，RA33的临床价值分析

目的:分析抗抗环瓜氨酸肽(CCP)、类风湿因子(RF)、抗角蛋白抗体(AKA)、抗链球菌溶血素"O"(ASO、)抗RA33抗体对类风湿关节炎诊断的临床价值。方法:选取2015年3月至2016年2月本院收治的79例类风湿关节炎患者视为观察组,另选取同期本院收治的85例非类风湿关节炎自身免疫疾病者视为对照组。比较类风湿关节炎和非类风湿关节炎患者抗CCP、RF、AKA、ASO、RA33阳性情况,对抗CCP、RF、AKA、ASO、RA33的特异度和敏感度予以分析。结果:两组患者的ASO阳性率比较无显著性差异(P0.05),观察组的抗CCP、RF、AKA、RA33阳性率显著高于对照组(P0.05)。抗CCP抗体诊断类风湿关节炎患者的敏感度为64.56%、特异度为92.94%;RF敏感度为60.46%、特异度为80.00%;AKA敏感度为51.90%、特异度为96.47%;ASO敏感度为10.13%、特异度为89.41%;抗RA33抗体敏感度为30.38%、特异度为95.29%。结论:抗CCP、RF、AKA、RA33对类风湿关节炎患者均具有较高的诊断价值,而ASO在类风湿关节炎患者中的诊断价值不明显。     

Serology of paracoccidioidomycosis

The purposes of the present work were: i) to study the positivity indices and compare titers obtained with the indirect immunofluorescence (II), tube precipitation (TP), complement fixation (CF) and double immunodiffusion on agar gel (ID) tests in the sera of 196 patients with paracoccidioidomycosis before treatment, and ii) to compare the initial titers of II with those obtained 1 year or more after treatment. II was the most sensitive serologic reaction (85.2%), and the positivity indices for CF, ID and TP were 67.7%, 66.0% and 50.0%, respectively. The sera tended to show parallel mean titers in II, CF and TP tests. One year after treatment there was a fall in titers of II in 66.2% of patients. The data, taken as a whole, demonstrate the usefulness of the indirect immunofluorescent test and the importance of using 2 or more serologic tests for the diagnosis and monitoring of patients with paracoccidioidomycosis.     

False-Positive Anti-Toxoplasma Fluorescent-Antibody Tests in Patients with Antinuclear Antibodies

The indirect fluorescent-antibody (IFA) method for diagnosis of toxoplasmosis is widely used and is considered to be as specific as the Sabin-Feldman dye test. After observing a patient with systemic lupus erythematosus (SLE) who had a positive toxoplasma IFA test but a negative dye test, we studied sera with high titers of antinuclear antibodies from 16 SLE patients and from 2 with rheumatoid arthritis for Toxoplasma antibodies in the immunoglobulin G and M (IgG and IgM) IFA tests and the dye test. Results of these tests were compared with titers of antinuclear antibodies, precipitating antibodies to single-strand deoxyribonucleic acid (DNA), and binding antibodies by use of DNA labeled with (3)H-actinomycin D. Of 18 patients, 11 had IgG and 4 had IgM IFA Toxoplasma antibodies; only 2 had antibodies detectable in the dye test. The immunofluorescence patterns in the Toxoplasma IFA test were indistinguishable from those obtained in patients with toxoplasmosis without antinuclear antibodies. Absorption of SLE sera with DNA did not result in a decrease in Toxoplasma IFA titers. When SLE sera were absorbed with live T. gondii, a marked drop in IgG IFA titer was observed as well as a decrease in titers of antinuclear antibodies and (3)H-DNA binding. Treatment of Toxoplasma cells with deoxyribonuclease and ribonuclease did not decrease their fluorescence. These results suggest that T. gondii nuclear antigens can absorb antinuclear antibodies but do not have exposed substrates for deoxyribonuclease. Tests in which organisms containing "nuclear" antigens for IFA detection of antibodies to these organisms are used may result in "false-positives" with sera containing antinuclear antibodies.     

Results of the National External Quality Assessment for Toxoplasmosis Serological Testing in China

Background

Toxoplasmosis is typically diagnosed by serologic testing. External quality assessment (EQA) of clinical laboratories could ensure the accuracy and reliability of serological tests. We assessed the quality of toxoplasma serological assays in Chinese clinical laboratories by an EQA performed between 2004 and 2013 by the National Center for Clinical Laboratories.

Methodology and Findings

EQA panels were prepared and shipped at room temperature to participating laboratories that employed toxoplasma IgG and IgM serological detection. By 2013, 5,384 EQA test reports for toxoplasma-specific IgM and 2,666 reports for toxoplasma-specific IgG were collected. Enzyme-linked immunosorbent (ELISA) and chemical immunofluorescent assays were the most commonly used detection methods. The overall coincidence rates of negative samples were better than those of positive samples. The overall EQA score for toxoplasma-specific IgM detection ranged between 84.3% and 99.6%. The ratio of laboratories that achieved correct IgG detection ranged from 61.1% to 99.3%. However, the inter- and intra-assay variabilities were found to be considerable. The most common problem was failure to detect low titers of antibody.

Conclusion

The EQA scheme showed an improvement in toxoplasma serological testing in China. However, further optimization of assay sensitivity to detect challenging samples remains a future challenge.     

Diagnostic testing for Legionnaires’ disease

Legionnaires’ disease is commonly diagnosed clinically using a urinary antigen test. The urinary antigen test is highly accurate for L. pneumophila serogroup 1, however other diagnostic tests should also be utilized in conjunction with the urinary antigen as many other Legionella species and serogroups are pathogenic. Culturing of patient specimens remains the gold standard for diagnosis of Legionnaires’ disease. Selective media, BYCE with the addition of antibiotics, allows for a high sensitivity and specificity. Culturing can identify all species and serogroups of Legionella. A major benefit of culturing is that it provides the recovery of a patient isolate, which can be used to find an environmental match. Other diagnostic tests, including DFA and molecular tests such as PCR and LAMP, are useful tests to supplement culturing. Molecular tests provide much more rapid results in comparison to culture, however these tests should not be a primary diagnostic tool given their lower sensitivity and specificity in comparison to culturing. It is recommended that all laboratories develop the ability to culture patient specimens in-house with the selective media.     

Molecular genetic testing in the United States: comparison with international practice

OBJECTIVE: To compare data on the practices of molecular genetic testing (MGT) in laboratories in the United States with those in 18 other countries. METHODS: A Web-based survey of MGT laboratory directors (n = 827; response rate 63%) in 18 countries on three continents was carried out, and the response from U.S. laboratories compared to all others. Quality assurance and reporting indices were developed and calculated for each responding laboratory. RESULTS: A comparison of U.S. results with all other countries identified differences in laboratory setting, personnel qualifications, and the specific tests being offered, but similar rates of adherence to MGT quality standards and reporting practices were found. The survey also documented substantial transborder flow of specimens, most commonly due to the lack of availability of the test in the United States or because the test was available only through a research protocol, highlighting the need for common reporting and practice guidelines for the international MGT community. CONCLUSION: The findings presented here provide further support for the need to consider the application of the Organisation for Economic Cooperation and Development (OECD) Guidelines and the establishment of compatible accreditation programs or equivalent mechanisms across national borders to ensure the quality of laboratory services and the clinical usefulness of molecular genetic test reports for referred specimens.