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At least 109 records · Page 6Linked to original sources
PubMed1992

The significance of western blot assays indeterminate for antibody to HIV in a cohort of homosexual/bisexual men. The Multicenter AIDS Cohort Study.

The objective of this study was to determine the frequency and significance of nondiagnostic Western blot (WB) assays in homosexual/bisexual men at risk of infection with HIV-1. The presence of a positive enzyme-linked antibody assay (EIA) confirmed by a positive WB was used as evidence of infection and seroconversion. Indeterminate WB assays were defined as reactions to only one viral gene product of HIV-1. Three analyses were conducted to (a) determine the frequency of such reactions in men who, during a 4-year period, did not develop diagnostic serologic reactions; (b) determine, retrospectively, the preseroconversion frequency of indeterminate WB assays in 286 men who seroconverted; and (c) evaluate in vitro production of specific antibody by peripheral blood mononuclear cells (PBMCs) as a method of indicating whether or not an indeterminate WB assay represents HIV-1 infection. Reactions to products of gag, pol, or env were noted in 8.0, 4.0, and 6.7% of 1,595 first-visit tests of men who remained seronegative for 4 years. Indeterminate reactions occurred in 204 men with negative EIAs who subsequently seroconverted and in 82 men with positive EIAs preconversion. Supernatants harvested from PBMCs of 2 of 36 seroconverters obtained one or two visits preseroconversion and cultured with pokeweed mitogen were antibody-positive. All were positive at the visit, with diagnostic serology. None of the supernatants from cells of 19 men with EIA-negative WB-indeterminate serologic assays were antibody-positive. Our results suggest that persistently EIA-negative homosexual/bisexual men who have indeterminate WB assays are unlikely to be infected with HIV-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Bisexuality↗
PubMed2004

Sucrose density gradient centrifugation and cross-flow filtration methods for the production of arbovirus antigens inactivated by binary ethylenimine.

BACKGROUND: Sucrose density gradient centrifugation and cross-flow filtration methods have been developed and standardised for the safe and reproducible production of inactivated arbovirus antigens which are appropriate for use in diagnostic serological applications. METHODS: To optimise the maximum titre of growth during the propagation of arboviruses, the multiplicity of infection and choice of cell line were investigated using stocks of Ross River virus and Barmah Forest virus grown in both mosquito and mammalian cell lines. To standardise and improve the efficacy of the inactivation of arboviral suspensions, stocks of Ross River virus, Barmah Forest virus, Japanese encephalitis virus, Murray Valley encephalitis virus and Alfuy virus were chemically inactivated using binary ethylenimine at a final concentration of 3 mM. Aliquots were then taken at hourly intervals and crude inactivation rates were determined for each virus using a plaque assay. To ensure complete inactivation, the same aliquots were each passaged 3 times in Aedes albopictus C6/36 cells and the presence of viral growth was detected using an immunofluorescent assay. For larger quantities of viral suspensions, centrifugation on an isopycnic sucrose density gradient or cross-flow filtration was used to produce concentrated, pure antigens or partially concentrated, semi-purified antigens respectively. RESULTS: The results of the propagation experiments suggested that the maximum viral titres obtained for both Ross River virus and Barmah Forest virus were affected by the incubation period and choice of cell line, rather than the use of different multiplicity of infection values. Results of the binary ethylenimine inactivation trial suggested that standardised periods of 5 or 8 hours would be suitable to ensure effective and complete inactivation for a number of different arboviral antigens. CONCLUSION: Two methods used to prepare inactivated arbovirus antigens have been standardised to minimise production failure and expenditure and to provide reagents that conform to the highest quality and safety requirements of a diagnostic serology laboratory. The antigens are suitable for use in either enzyme linked immunosorbent assays or haemagglutination inhibition assays and the optimised protocols can be directly applied to produce antigens from new or emerging arboviral pathogens.

Aedes↗
PubMed2002

Renal histology in ANCA-associated vasculitis: differences between diagnostic and serologic subgroups.

BACKGROUND: Differences in renal histopathology between microscopic polyangiitis (MPA) and Wegener's granulomatosis (WG), and between anti-neutrophil cytoplasm autoantibody (ANCA) test results in patients with ANCA-associated vasculitis may provide insight into the differences in pathogenesis and raise the opportunity of classifying the vasculitides more accurately. The possible differences in histopathology are investigated in this study. METHODS: We report an analysis of 173 patients with renal disease in microscopic polyangiitis or Wegener's granulomatosis. A total of 173 renal biopsies, performed at diagnosis, were scored by two observers separately, using a previously standardized protocol. Consensus on each biopsy was achieved during a central review. RESULTS: Normal glomeruli were more common in WG than in MPA (P < 0.001). Glomerulosclerosis was more prominent in MPA than in WG (P=0.003). Interstitial fibrosis (P < 0.001), tubular atrophy (P < 0.001), and tubular casts (P=0.005) were more frequently present and more severe in MPA than in WG. Presence of glomerulosclerosis was more extensive in patients with myeloperoxidase (MPO)-ANCA than with proteinase 3 (PR3)-ANCA (P=0.022). Interstitial fibrosis (P=0.008), tubular necrosis (P=0.030), tubular atrophy (P=0.013), and intra-epithelial infiltrates (P=0.006) were more frequently present and more severe in MPO-ANCA than in PR3-ANCA. CONCLUSIONS: Glomerulonephritis in relation to MPA has more characteristics of chronic injury at the time of presentation than glomerulonephritis in relation to WG. This difference may be due to a delayed establishment of diagnosis in patients with MPA compared to patients with WG. Both active and chronic lesions are more abundantly present in MPO-ANCA-positive patients than in patients with PR3-ANCA-positivity, which suggests that the pathogenesis of renal disease in these ANCA subsets could be different. Our results also suggest that ANCA test results may be useful in classifying ANCA-associated vasculitides.

Antibodies, Antineutrophil Cytoplasmic↗
PubMedDate not supplied

Reevaluation of diagnostic histoplasma serologies.

There are few quantitative guidelines for the interpretation of serologic tests for histoplasmosis. Furthermore, guidelines that have been proposed are not accepted generally. This report reviews experiences with complement fixation and latex agglutination tests performed in a large acute-care hospital in an endemic area, and depicts the relationship between the proportion of false-positive reactions and the titer at which the serologic tests were reactive. We noted a considerable number of false-positive reactions for these widely-used tests. Use of a battery of standard tests for histoplasmosis resulted in a 90% decrease in false-positive reactions. Reliance upon multiple positive results in such a battery of tests would result in failure to detect 50% of cases of disseminated histoplasmosis, but would eliminate most false positives.

Complement Fixation Tests↗
PubMed2001

Chlamydial serology: comparative diagnostic value of immunoblotting, microimmunofluorescence test, and immunoassays using different recombinant proteins as antigens.

To improve the reliability of the serodiagnosis of Chlamydia trachomatis infections, an immunoblot analysis, a microimmunofluorescence titration, and different immunoassays using synthetic peptides derived from species-specific epitopes in variable domain IV of the major outer membrane protein or recombinant antigens (heat shock protein 70 [hsp70], hsp60, hsp10, polypeptide encoded by open reading frame 3 of the plasmid [pgp3], macrophage infectivity potentiator, and a fragment of the total lipopolysaccharide) were evaluated. Because cross-reactions between chlamydial species have been reported, the microimmunofluorescence tests were also performed with Chlamydia pneumoniae and Chlamydia psittaci used as antigens, and C. pneumoniae-specific antibodies were also determined by immunoassays. Since the presence of antimicrobial antibodies must be interpreted in light of their prevalence in the general population, responses obtained with serum samples from patients with well-defined infection (i.e., with positive urethral or endocervical C. trachomatis DNA amplification) were compared to those obtained with samples from healthy blood donors. The best sensitivity (86%) with a specificity of 81% was obtained for immunoblotting results, when the number of individuals with > or =10 immunoglobulin G (IgG) and/or > or =2 IgM responses to the different C. trachomatis antigens was considered. A 13-kDa antigen was recognized by most of the samples (86% for IgG) from patients with acute urogenital infection but rarely (3%) by those from healthy blood donors (P < 0.0001). The sensitivity and specificity results obtained for serum antibodies to peptides or recombinant antigens were slightly lower than those results obtained for the number of responses to whole C. trachomatis antigens, which were 76 and 77%, respectively, when IgG responses to both recombinant hsp60 and pgp3 were considered.

Adolescent↗
PubMed1975

Practical application of diagnostic virus serology.

A number of virologists have suggested that current methods of virus serology are impractical and should be discontinued. An evaluation of the results in our laboratory showed positive confirmation in 1,571 of 6,599 suspected clinical cases or 23.6% including hundreds of cases which were still in the hospital or under the care of the physician. Further analysis of these 1,571 cases revealed that 75.9% had antibody titers in the acute specimen. These results suggest that optimal utilization is not being made of information currently available and that a practical service can be provided locally in most cases with existing techniques simply by more frequent sampling and testing of the patients' sera.

Disease Outbreaks↗
PubMed1994

[Evaluation of occurrence of infections caused by Mycoplasma pneumoniae during 1970-1973 based on serological investigations].

During the years 1970-1993 diagnostic serological tests directed against infection with M. pneumoniae were performed in 89,155 persons, mostly children at the preschool and school age with clinical symptoms of respiratory tract infections. Investigations were performed by application of the complement fixation test with cellular antigen of M. pneumoniae. Positive result was established when antibody titer was 60 or higher, or at least four-fold increase o titer occurred during the illness. During performance of these studies five epidemics of mycoplasmosis were noted in Poland. They occurred during the autumn-winter season in 1970/71, 1975/76, 1980/81, 1985/86 and 1991-1993. At the peak of the epidemic depending of the region of country, in 25-38% of patients with pneumonia serological confirmation of mycoplasmosis was established. In selected group of 251 persons which consisted in 87% of hospitalized patients with pneumonia, serological test was repeated at least twice during 7-10 days confirming mycoplasmal etiology of illness in 48.6% of cases. It was found that performance of serological test only once during first week of clinical symptoms of the disease decreases chances of mycoplasmosis diagnosis by 53%.

Bronchial Diseases↗
PubMedDate not supplied

[An evaluation of the effectiveness of laboratory diagnostic methods for brucellosis].

The diagnostic value of bacteriological and serological methods for the laboratory diagnosis of brucellosis was studied. In the analysis of milk and cheese specimens Brucella cultures were isolated and differentiated as B.melitensis, biovar I, and B.abortus, biovar 4. In 25.6% of cases B.melitensis culture, biovar 1, was isolated from the blood of persons suspected for brucellosis. The isolation of B.melitensis culture from milk showed that this infective agent migrated from small animals to cattle, which was indicative of a high risk of human infection in the state of Zacatecas, Mexico. The comparative evaluation of serological diagnostic methods (the agglutination test in test tubes, Huddleson's slide test, the acidic rose bengal test and the 2-mercaptoethanol test) showed high sensitivity of rapid tests (Huddleson's test and the rose bengal test in 93.7% and 87.9% of cases respectively). The 2-mercaptoethanol test which gave positive results in 63.8% of cases provided additional information characterizing the course of infections process.

Animals↗
PubMed1996

Usefulness and limitations of three serologic methods for diagnosing or excluding chlamydiosis in birds.

Diagnostic serology by use of elementary body agglutination is the most useful serologic method for diagnosis of chlamydiosis in birds, because it detects only IgM activity. A titer of 10 in budgerigars, cockatiels, and lovebirds and of > or = 20 in other types of birds is interpreted as being indicative of current infection. Latex agglutination, with detects IgM and IgG activity, may be useful in detecting large changes in titer. Direct complement fixation, detecting only IgG activity, is usable to detect past infection whenever elementary body agglutination and latex agglutination titers are < 10. Limitations of serologic results necessitating additional confirmatory testing are lack of titers in the acute phase of disease and diagnostic titers in clinically normal birds with low-grade chronic infections and in birds with prolonged maintenance of titers. Additional suggested examinations are chlamydial culture by use of choanal/oropharyngeal swab samples, WBC count, determination of hepatic-associated enzyme activity, chlamydial ELISA by use of the aforementioned swab samples, and additional serologic testing.

Agglutination Tests↗
PubMed2000

["Rapid" serology for the diagnosis of Helicobacter pylori infection. Evaluation of its accuracy compared with a gold-standard and its concordance with "classic" serology].

AIM: To prospectively evaluate the validity of a rapid office-based diagnostic serological test (using capillary blood) in our population, taking as reference a combination of standard diagnostic methods, as well as to compare the results of this technique with those of "classic" serological tests (using venous blood). PATIENTS AND METHODS: We prospectively studied 39 consecutive patients with symptoms of the upper digestive tract who had undergone oral gastroscopy. Gastric biopsies were taken for histology and rapid urease testing, and a 13C-urea breath test was performed. An enzyme-linked immunoassay that detects IgG antibodies against Helicobacter pylori was used as a "classic" serological test and the commercial kit FlexPack HP was used as a "rapid" serological test. The endoscopist, the pathologist and those responsible for reading the rapid urease test, the 13C-urea breath test and both serological tests did not know the results of the other diagnostic methods. Patients were considered H. pylori positive when at least two of the three validated tests (rapid urease test, histology, and 13C-urea breath test) revealed infection and were considered free of infection when all tests were negative. RESULTS: Thirty-nine patients were studied. Thirty-eight per cent were male (mean age 48 +/- 15 years). The prevalence of H. pylori infection detected by the gold standard was 69.2%. The sensitivity and specificity of the "classic" serological test was 96% 95% (CI: 79-99) and 91% (59-100). "Rapid" serological testing was positive in nine patients, negative in 28 and indeterminate in two. A single digital puncture was sufficient in 80% of the patients, 15% needed two and 5% needed three. Most patients (77%) had no preference for either type of serological test while 20.5% preferred digital puncture and 2.5% venous puncture. The sensitivity, specificity, positive predictive value and negative predictive value were 31% (16-50), 91% (59-100), 89% (52-100) and 36% (19-56) respectively. Sensitivity was unaffected by age but specificity was lower in patients older than 40 years (89% vs. 100%; McNemar's test: 8; p < 0.01). Kappa's coefficient between the "classic" and the "rapid" serological tests was 0.16 (SE 0.1) and McNemar's test was 12.2 (p < 0.001), which indicates that the prevalence of infection diagnosed by both methods was not homogeneous. CONCLUSION: The "rapid" office-based serological test used in our study is of insufficient diagnostic accuracy to be used in clinical practice to identify H. pylori infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed1997

Comparison between a rapid office-based and ELISA serologic test in screening for Helicobacter pylori in children.

BACKGROUND: The rapid diagnostic serological test for detection of Helicobacter pylori (H. pylori) infection in children has a significant advantage over the standard enzyme immunoassay (EIA) method, for its simplicity and rapid availability of results in a physician's office setting. We compared the immunochromatographic test with a standard enzyme immunoassay test in the pediatric population. MATERIALS AND METHODS: A retrospective analysis of 1147 serum samples from asymptomatic children and prospective analysis of 62 serum samples from symptomatic children undergoing diagnostic upper endoscopy were evaluated for the detection of H. pylori antibody by two commercially available serology tests. Each serum sample was tested by a rapid test (FlexSure HP, SmithKline Diagnostics, Inc.) and compared to the standard EIA method (HM-CAP, Enteric Products, Inc.). RESULTS: The rapid test, FlexSure HP, was comparable to the rapid EIA test in screening for H. pylori infection in symptomatic and asymptomatic children with sensitivity and specificity of 83-90% and 90-100%, respectively. Both methods had a comparable sensitivity and specificity for the detection of H. pylori-associated gastritis (60-70% and 94%, respectively). CONCLUSION: The rapid test is comparable to the standard EIA test and may be used by physicians in symptomatic children. The use of FlexSure HP as a screening tool for the prevalence of H. pylori infection in asymptomatic children may be limited by its low positive predictive value compared to the EIA method.

Adolescent↗
PubMed1993

Rational diagnosis and treatment in unclassified arthritis: how clinical data may guide requests for Lyme serology and antibiotic treatment.

To improve the appropriateness and efficiency of diagnostic serological tests and subsequent antibiotic treatment, clinical data from 102 patients with unclassified arthritis were analysed to investigate whether the presence of positive IgG antibodies to Borrelia burgdorferi could be predicted. The clinical data were blindly ranked from 1 to 4 (1, Lyme arthritis unlikely; 4, Lyme arthritis very likely). Antibodies to B burgdorferi were positive in nine of 102 patients (9%). Six of 15 (40%) patients with rank numbers 3 and 4 were positive for antibodies to B burgdorferi, in contrast with only three of 87 (3%) patients with rank numbers 1 and 2. The likelihood ratio of positive Lyme serology for patients ranked 3 and 4 was 12.0, for patients ranked 2 to 4, 4.5, and for patients with arthritis of the knee, 3.0. These likelihood ratios were associated with a post-test probability of 55, 30, and 20% respectively. The clinical history in patients with unclassified arthritis can largely predict the presence of antibodies to B burgdorferi. The absolute value of a likelihood ratio can be a contributing factor in deciding to request tests for antibodies to B burgdorferi in patients with unclassified arthritis.

Adolescent↗
PubMed1993

Serological testing for campylobacteriosis with sera forwarded for Salmonella and Yersinia serology.

Single serum specimens forwarded for Salmonella and Yersinia serology, from a total of 250 patients, were tested for anti-C. jejuni antibodies of the IgG class. Anti-Salmonella and anti-Y. enterocolitica O3 antibodies were examined by a microagglutination test and anti-C. jejuni antibodies by ELISA against a C. jejuni ultrasonicate before (ELISA) and after neutralization of antibodies which cross-reacted with Helicobacter pylori antigens (ELISA-Abs). Blood donor sera (n = 50) and sera (n = 40) from patients with various infectious diseases served as controls. A positive test for anti-Salmonella antibodies was recorded in 4/250 (1.6%) of the patients, for anti-Yersinia antibodies in 7/250 (2.8%), and for anti-C. jejuni antibodies in 7/250 (2.8%) in the ELISA; in 25/250 (10%) in the ELISA-Abs. No mixed infection was recorded by the serological testing. The ELISA-Abs showed a diagnostic specificity of 97.7%. Our results support the inference that diagnostic serology for enteropathogenic bacteria should include serology for C. jejuni, preferably by tests which exclude participation by antibodies which cross-react with H. pylori antigens.

Antibodies, Bacterial↗