Definition of a diagnostic routine in individuals with inconclusive serology for chagas disease

Despite the existence of highly sensitive tests, inconclusive serological results are frequent in chronic chagasic infection. This study aimed to define a diagnostic conduct for 30 individuals with inconclusive serology (G3) for chagasic infection assisted at the Outpatient Unit for Infectious and Parasitic Diseases of the Botucatu School of Medicine. Twenty-one individuals with negative serology (G1) and 33 with positive serology (G2) were also studied. Serological methods ELISA, HAI, IFI and immunoblotting TESA-cruzi were used for G1, G2 and G3, and parasitological methods xenodiagnosis, hemoculture and PCR-LIT were used for G2 and G3 individuals. ELISA, HAI and IFI were performed in 5 different blood samples in G2 and G3. TESA-cruzi was carried out only once in G1, G2 and G3 and, since it is the most sensitive, it was utilized as standard. In G3, positivity for ELISA reached 86% in the fifth blood sample; the ELISA+HAI+IFI combination showed a maximum of 44.8% in the second sample; and TESA-cruzi, 76% in one single sample. Xenodiagnosis positivity was 9.4%; hemoculture showed 15.2%; and PCR-LIT exhibited 22% positivity in G2. Nevertheless, in G3, positivity percentage was 3.4% for xenodiagnosis, 6.7% for PCR-LIT, and no positive result was found for hemoculture. In G3, PCR-LIT resolved one case which was still inconclusive according to serology tests. In order to define inconclusive diagnoses, the results suggest the combined use of ELISA+HAI+IFI in 2 blood samples, decreasing the occurrence of false positive/negative results. If results remain inconclusive, the performance of TESA-cruzi and PCR-LIT, if necessary, is recommended.

The placenta as a barrier for toxic and essential elements in paired maternal and cord blood samples of South African delivering women

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Serology for Brucella abortus in cart horses from an urban area in Brazil

Avaliou-se a infecção por Brucella abortus em cavalos de carroça de Curitiba e São José dos Pinhais-PR. Um total de 123 amostras foi submetido ao teste do antígeno tamponado acidificado (ATA), soroaglutinação lenta em tubos (SAL) e prova do 2-mercaptoetanol (2-ME) para confirmação dos resultados. Oito (6,5%) equinos foram positivos para o ATA e um animal permaneceu positivo ao teste confirmatório. Existem evidências da presença de brucelose entre os cavalos de carroça.

Serology of paracoccidioidomycosis. II. Correlation between class-specific antibodies and clinical forms of the disease

Untreated and previously treated patients with paracoccidioidomycosis were studied for: (i) serum levels of total IgG, IgM and IgA immunoglobulins, by radial immunodiffusion and Paracoccidioides brasiliensis (Pb) antibodies, by indirect immunofluorescence; (ii) correlation between their levels with the clinical forms of the disease; (iii) correlation between the serum titres obtained by tube precipitin with those of anti-Pb IgG, IgM and IgA. In the untreated group, serum IgG levels were significantly increased in patients with the more systemic forms of the disease, especially the acute progressive form. Serum IgA levels were significantly increased in all patients with no statistical difference between clinical forms. Serum IgM levels were normal in all patients. Anti-Pb IgG, IgA and IgM were detected in 97·5%, 32·5% and 45·0% of all cases, respectively. There was a sharp tendency towards higher levels of anti-Pb IgG among those with the acute progressive form (83·4%) in relation to the chronic, more localized forms, mixed form (68·0%) and isolated organic form (55·5%). In the untreated and previously treated group sera, there was positive correlation between the level of anti-Pb IgG and positivity for the tube precipitin test, suggesting that the precipitin-type antibodies are of the IgG class. Broadly, the present data demonstrate a polyclonal activation of the humoral immune system in paracoccidioidomycosis, with a positive relationship between serological results and severity of the disease. © 1984.

Serology of paracoccidioidomycosis - I. Evaluation of the indirect immunofluorescent test

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. © 1985 Martinus Nijhoff/Dr W. Junk Publishers.

Use of the paired samples (cerebrospinal fluid and serum) in immunodiagnostic of active and inactive human neurocysticercosis

Paired samples of cerebrospinal fluid (CSF) and serum of 30 patients - 10 with active, 10 with inactive neurocysticercosis (NCC), and 10 control subjects - were evaluated by enzyme-linked immunosorbent assay (ELISA) using two Taenia crassiceps metacestode extracts as antigen in order to detect IgG antibodies. In active NCC, high levels of IgG were detected (p < 0.05). The CSF samples showed 80% (CI 72-88) of reactivity in the saline extract (S) and 90% (CI 84-95) in sodium dodecyl sulphate (SDS) and the serum samples were reactive in 90% (CI 84-95) and 100% (CI 98-100) in the S and SDS antigenic extracts, respectively. The use of the paired samples of CSF and serum in active NCC showed equivalent results suggesting that the serum samples could be used as a screening in those patients whose CSF puncture is counter-indicated.

Evaluation of IFA, MAT, ELISAs and immunoblotting for the detection of anti-Toxoplasma gondii antibodies in paired serum and aqueous humour samples from experimentally infected pigs

The study evaluated the efficiency of diagnostic laboratory methods to detect anti-Toxoplasma gondii antibodies in paired serum and aqueous humour samples from experimentally infected pigs. 18-mixed breed pigs were used during the experiment; these were divided into two groups, G1 (infected group, n = 10) and G2 (uninfected group, n = 8). Infection was performed with 4 × 10 4 VEG strain oocysts at day 0 by the oral route in G1 animals. All pigs were euthanized at day 60, when retina, aqueous humour, and blood samples were collected. Anti-T. gondii antibody levels were assessed in serum (s) and aqueous humour (ah) by indirect immunofluorescence assay (IFA), modified agglutination test (MAT), m-ELISA (using crude membranes from T. gondii tachyzoites as antigen) and r-ELISA (using rhoptries from T. gondii tachyzoites as antigen). Polymerase chain reactions (PCR) of samples from the retina were performed by using Tox4 and Tox5 primers. Antibody titers of G1 animals ranged from 128 to 1024 and from 16 to 256 in serum and aqueous humour, respectively. There were differences in the correlation coefficients between IFA(s) × IFA (ah) (r = 0.62, P = 0.05), MAT(s) × MAT (ah) (r = 0.97, P < 0.0001); however, there was no significant difference between r-ELISA(s) × r-ELISA (ah) (r = 0.14, P = 0.7). Antibodies present in serum and aqueous humour recognized similar antigens. Samples of retina were positive by PCR in 30% (3/10) of infected pigs. G2 animals remained without antibody levels and were PCR negative throughout the experiment. These results suggest that the use of a combination of tests and immunoblotting for paired aqueous humour and serum samples could improve the sensitivity and specificity for the diagnosis of ocular toxoplasmosis. © 2007 Elsevier Ltd. All rights reserved.

Infecção congênita pelo citomegalovírus: estudo realizado na Fundação Santa Casa de Misericórdia do Pará

O citomegalovírus é um vírus de DNA, pertencente à família Herpesviridae, subfamília Beta-herpesvirinae. Sua distribuição é universal e pode causar infecções congênitas e perinatais, assim como durante a infância e na idade adulta. É um dos principais patógenos responsáveis pela morbidade e mortalidade em pacientes imunocomprometidos. Foi estudada a incidência da infecção congênita pelo citomegalovírus, na maternidade da Fundação Santa Casa Misericórdia do Pará, no período de novembro de 1994 a maio de 1995. A amostra trabalhada constou de 663 recém-nascidos e suas respectivas mães. O peso dos recém-nascidos variou de 900 a 5450 g, com uma média de 3046g. Em 11,4% das crianças foi observado baixo peso ao nascer. A avaliação pelo isolamento do vírus da saliva dos 663 recém-nascidos, através da inoculação em células primárias de fibroblasto de prepúcio humano, mostrou 3,2% (21) de positividade. A pesquisa de anticorpos IgM específicos para o CMV, através do método ELISA, utilizando-se sangue do cordão umbilical do mesmo grupo de recém-nascidos foi positiva em 2,1% (14). Para o diagnóstico da infecção congênita pelo CMV, a análise estatística pelo Teste de McNemar dos Pares Discordantes (p)=0,0233 e Teste do Qui-Quadrado da Homogeneidade (p)<0,01 demonstrou que o isolamento do citomegalovírus da saliva foi mais sensível que a detecção de anticorpos IgM no sangue do cordão umbilical. Dos 21 recém-nascidos infectados, 28,5% (6) apresentaram nas primeiras 24 horas de vida, sintomatologia sugestiva de infecção congênita. Os sinais e sintomas encontrados foram microcefalia (4), prematuridade (3), hepatoesplenomegalia (2), pequeno para a idade gestacional (2) e icterícia precoce (1). A pesquisa de anticorpos IgG específicos para o CMV, pelo método ELISA, foi positiva em 90,2% das puérperas. Das 21 mulheres que transmitiram o vírus para o concepto, foram detectados anticorpos IgM em 4. A entrevista pessoal com as mães dos recém-nascidos revelou nível socioeconômico baixo e assistência pré-natal deficiente, com 26,4% das puérperas sem nenhuma consulta durante o período gestacional. Em nossa amostra, a idade materna variou de 12 a 42 anos, com idade média de 22,2 anos, sendo que a idade das mães dos recém-nascidos infectados foi inferior a 25 anos.

Serology, isolation, and molecular detection of Leptospira spp. from the tissues and blood of rats captured in a wild animal preservation centre in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Serology for brucellosis in free-ranging crab-eating foxes (Cerdocyon thous) and brown-nosed coatis (Nasua nasua) from Brazilian Pantanal

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development of twenty-one polymorphic microsatellite markers for the fungus-growing ant, Mycocepurus goeldii (Formicidae: Attini), using Illumina paired-end genomic sequencing

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Advances and challenges in paracoccidioidomycosis serology caused by Paracoccidioides species complex: an update

Understanding the possible methodologies for the rapid and inexpensive identification of fungal infections is essential for disease diagnosis, but there are some limitations. To help with this problem, serological methods that detect antigens or antibodies are widely used and are useful for the diagnosis of paracoccidioidomycosis (PCM) through the detection of gp43, which is the main antigen employed for the immunodiagnosis of this disease caused by Paracoccidioides brasiliensis. However, the use of gp43 has become restricted because it was recently found that this marker is not identified in the infections caused by Paracoccidioides lutzii. Therefore, it is necessary to identify new antigens in both species or antigens specific for P. lutzii to decrease the morbidity and/or mortality associated with PCM. This review provides a discussion of new diagnostic challenges after the recent discoveries regarding the taxonomy of the Paracoccidioides genus.

Base-Paired and Base-Stacked Structures of the Anti-HIV Drug Lamivudine: A Nucleoside DNA-Mimicry with Unprecedented Topology

We have prepared a DNA-mimicry of nucleosides in which the anti-HIV drug lamivudine (beta-L-2',3'-dideoxy-3'-thiacytidine, 3TC) self-assembles into a base-paired and helically base-stacked hexagonal structure. Face-to-face and face-to-tail stacked 3TC=3TC dimers base-paired through two hydrogen bonds between neutral cytosines by either N-H center dot center dot center dot O or N-H center dot center dot center dot N atoms give rise to a right-handed DNA-mimicry of lamivudine with an unusual highly symmetric hexagonal lattice and topology. In addition, a base-paired and base-stacked supramolecular architecture of lamivudine hemihydrochloride hemihydrate was also obtained as a result of our crystal screenings. This structure is formed through partially face-to-face stacked lamivudine pairs held together by protonated and neutral fragments. However, no helical stacking occurs in this structure in which lamivudine also adopts unusual conformations as the C1'-endo and C1'-exo sugar puckers and cytosine orientations intermediate between the anti and syn conformations. As a conclusion drawn from the nucleoside duplex, the hexagonal DNA-mimicry of lamivudine reveals that such double-stranded helices can be assembled without counterions and organic solvents but with higher crystallographic symmetry instead, because only water crystallizes together with lamivudine in this structure.

Performance of six diagnostic tests to screen for Chagas disease in blood banks and prevalence of Trypanosoma cruzi infection among donors with inconclusive serology screening based on the analysis of epidemiological variables

OBJECTIVE: The frequent occurrence of inconclusive serology in blood banks and the absence of a gold standard test for Chagas'disease led us to examine the efficacy of the blood culture test and five commercial tests (ELISA, IIF, HAI, c-ELISA, rec-ELISA) used in screening blood donors for Chagas disease, as well as to investigate the prevalence of Trypanosoma cruzi infection among donors with inconclusive serology screening in respect to some epidemiological variables. METHODS: To obtain estimates of interest we considered a Bayesian latent class model with inclusion of covariates from the logit link. RESULTS: A better performance was observed with some categories of epidemiological variables. In addition, all pairs of tests (excluding the blood culture test) presented as good alternatives for both screening (sensitivity > 99.96% in parallel testing) and for confirmation (specificity > 99.93% in serial testing) of Chagas disease. The prevalence of 13.30% observed in the stratum of donors with inconclusive serology, means that probably most of these are non-reactive serology. In addition, depending on the level of specific epidemiological variables, the absence of infection can be predicted with a probability of 100% in this group from the pairs of tests using parallel testing. CONCLUSION: The epidemiological variables can lead to improved test results and thus assist in the clarification of inconclusive serology screening results. Moreover, all combinations of pairs using the five commercial tests are good alternatives to confirm results.