Publications by authors named "Márcia C A Teixeira"

14 Publications

  • Page 1 of 1

Effect of dexamethasone on experimental enteritis produced by Giardia lamblia in a Meriones unguiculatus model.

Exp Parasitol 2021 Sep 15;230:108158. Epub 2021 Sep 15.

Department of Parasitology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address:

Our aim was to evaluate the impact of immunosuppression on the development of giardiasis. Thirty-six gerbils (4-6 weeks old) were distributed in four groups containing nine animals each: Control (CT); Control-Infected by Giardia lamblia (CTIn), Immunosuppressed (IS), and Immunosuppressed-Infected by G. lamblia (ISIn). Animals in the IS and ISIn groups received intramuscular dexamethasone solution for 25 days. On the 11th day, the animals in the CTIn and ISIn groups were inoculated with G. lamblia. After 14 days of infection, the 25th day of the experiment, all groups were euthanized. Four hours after euthanasia, the intestinal permeability was evaluated and sections of the duodenum and spleen were harvested for morphometric and histopathological analyses. Immunosuppressed groups showed a significant increase in intestinal permeability compared to control and infected groups. Considering that the infection can become chronic in immunosuppressed groups, we should be alert to the possibilities of chronic inflammatory changes, both locally and systemically, due to the loss of the intestinal barrier. Lesions were observed in the duodenal mucosa of the gerbils of the CTIn group, with reduced villi size, crypt hyperplasia, edema, and the presence of inflammatory infiltrate in the lamina propria. In the ISIn group, we observed no inflammation, long and intact villi, and a significant increase in the area of intestinal mucins, despite the large number of trophozoites identified. Our results suggest that exacerbation of the immune response has a direct relationship with the appearance of lesions during enteritis produced by G. lamblia in the assessed model.
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http://dx.doi.org/10.1016/j.exppara.2021.108158DOI Listing
September 2021

in Alcoholic Patients: Implications of Alcohol Intake in the Frequency of Infection and Parasite Load.

Pathogens 2020 May 28;9(6). Epub 2020 May 28.

Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, Bahia 40170115, Brazil.

infection in immunocompromised subjects, including chronic alcoholics, can lead to a severe disease. Moreover, its prevalence in alcoholic patients seems to be higher than that in the general population. The aims of this study were to evaluate the frequency of infection in alcoholic patients and to investigate the influence of alcohol intake on the parasite load, as well as to evaluate the sensitivity of three different parasitological methods according to the larval output. Fecal samples of 1290 chronic alcoholic patients were examined by spontaneous sedimentation, Baermann-Moraes, and agar plate culture (APC) methods. was the most frequent parasite found (14.5%; n = 187). Alcoholic individuals infected with had a higher daily consumption of alcohol than those who were not infected, 528.6 and 403.0 g/day, respectively (p < 0.05). In addition, individuals with higher alcohol intake presented an increase in parasite load. The diagnostic method with the highest sensitivity was APC, 97.9% (183/187). In conclusion, seems to be the most frequent parasite found in alcoholic individuals from endemic areas and alcohol intake is positively associated with larvae output. In addition, this study confirms that APC is the most sensitive parasitological method used for diagnosis.
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http://dx.doi.org/10.3390/pathogens9060422DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350291PMC
May 2020

A Cross-Sectional Study of Complex in Salvador, Bahia, Brazil.

Biomed Res Int 2019 24;2019:7523670. Epub 2019 Jul 24.

Advanced Public Health Laboratory, Gonçalo Moniz Institute, FIOCRUZ-BA, Salvador-BA 40296-710, Brazil.

Epidemiological studies on species-specific infections are scarce due to the morphological similarity of pathogenic and nonpathogenic and . The diagnosis of is frequently based on coproantigen (-Gal/GalNAc lectin specific) detection by immunoassays. However, specific -lectin is not expressed in cysts, which are eliminated by asymptomatic individuals leading to false-negative results and an underestimation of amebiasis prevalence. Molecular techniques based on the amplification of parasite DNA have been shown to be a highly sensitive and specific method that allows the detection of different species. This study aimed to assess the frequency of the species from complex by molecular and immunological techniques in individuals attended at a public health system in Salvador-Bahia, Brazil. A cross-sectional study involving 55,218 individuals was carried out. The diagnosis was based on microscopy revealing complex. The species differentiation was performed by -specific antigen, serological evaluation and by molecular technique. The overall prevalence of complex determined by microscopy was approximately 0.49% (273/55,218). -specific antigen detection and molecular characterization returned 100% negativity for . However, serological evaluation returned an 8.9% positivity (8/90). In the stool samples analysed by PCR, it was not possible to identify and , although circulating IgG anti- has been detected.
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http://dx.doi.org/10.1155/2019/7523670DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6681611PMC
January 2020

Immune response markers in sera of children infected with Giardia duodenalis AI and AII subassemblages.

Immunobiology 2019 07 3;224(4):595-603. Epub 2019 Apr 3.

Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, Brazil. Electronic address:

In this study, we evaluated serum markers of immune responses in children infected with G. duodenalis and compared them with the characterized parasite isolates. The reactivity indexes (RI) of IgG (1.503 ± 0.819) and IgA (2.308 ± 1.935) antibodies were significantly higher (P < 0.001) in infected children than in non-infected children. There were also statistically significantly higher serum levels (P < 0.05) of IFN-γ (393.10 ± 983.90 pg/mL) as well as serum (30.03 ± 10.92 μmol/L) and saliva nitric oxid derivatives (NO) (192.4 ± 151.2 μmol/L) in children infected with G. duodenalis compared to the group of non-parasitized children (127.4 ± 274.30 pg/mL; 25.82 ± 7.74 μmol/L and 122.5 ± 105.90 μmol/L, respectively). Regarding the characterized genetic variants of G. duodenalis and the immune response profiles, no differences were observed in terms of antibody reactivity or levels of serum cytokine and NO among children infected with AI or AII subassemblages. The elevated levels of IFN-γ and NO indicate that G. duodenalis intestinal infection in humans induces a cellular immune response detectable at the systemic level. Moreover, no significant differences in the antibody reactivity profile or the cytokine and NO production in the sera of children infected with AI or AII G. duodenalis variants were observed, suggesting that subtypes of the parasite do not influence the immune response profile.
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http://dx.doi.org/10.1016/j.imbio.2019.04.001DOI Listing
July 2019

Urinary Tract Infection by Strongyloides stercoralis: A Case Report.

J Parasitol 2018 08 15;104(4):433-437. Epub 2018 May 15.

Faculdade de Farmácia, Universidade Federal da Bahia-R. Barão de Jeremoabo, 147 Ondina, Salvador BA, 40170-115, Brazil.

The objective of this study was to report a case of a hydronephrotic patient with Strongyloides stercoralis infection, with discharge of rhabditoid larvae exclusively in urine. In 2013, a 72-yr-old male patient, hypertensive, obese, and diagnosed with hydronephrosis secondary to renal calculi, reported lumbar pain, polyuria, polaciuria, and dysuria, as well as frequent urinary tract infections. The microscopic analysis of urine sediment showed the presence of S. stercoralis rabditoid larvae. However, parasitological examinations by Baermann-Moraes, agar plate culture, and spontaneous sedimentation performed with 3 fecal samples on alternate days had negative results. The patient was treated with albendazole and to date has shown negative results in both parasitological and urine tests. This report deals with the unusual finding of S. stercoralis in a urine sample of an immunocompetent individual and absence of disseminated infection, but with hydronephrosis. Patients with nephropathies from S. stercoralis-endemic areas should be monitored periodically, as early detection may prevent the worsening of symptoms and renal failure.
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http://dx.doi.org/10.1645/17-88DOI Listing
August 2018

Sera from Visceral Leishmaniasis Patients Display Oxidative Activity and Affect the TNF- Production by Macrophages .

Biomed Res Int 2017 5;2017:5861453. Epub 2017 Nov 5.

Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, BA, Brazil.

Mammalian protection against leishmanial infection depends on the development of an effective immune response. Zoonotic visceral leishmaniasis (ZVL) patients are usually unable to mount an effective immune response against the parasite and indeed appear to be severely immunosuppressed. This suppression has strong nonspecific and specific components mediated by serum factors and leishmanicidal activity of infected macrophages, respectively. The lipid profile has been shown to be altered in ZVL patients' sera. This work aimed at (i) determining the HDL, Apo A1, LDL, and VLDL concentrations in ZVL patients' sera; (ii) investigating the oxidative effect of ZVL patients' sera on the -carotene matrix; (iii) measuring IL-10, IL-6, IL-12p40, and tumour necrosis factor- (TNF-) concentrations in the macrophage cultures, to which 10% of ZVL patients' serum had been added. Levels of HDL, LDL fraction, and apolipoprotein A1 in ZVL patients' sera were lower than those of healthy individuals' sera, except for the mean level of VLDL. The matrix of -carotene and linoleic acid system was oxidized in the presence of ZLV patients' sera. The presence of ZVL patients' sera did not modify the cytokine production of IL-6, IL-12p40, and IL-10 by human macrophages but TNF- production was altered, probably due to lack of macrophage stimulation by lipoprotein.
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http://dx.doi.org/10.1155/2017/5861453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5694613PMC
July 2018

Infection in Alcoholic Patients.

Biomed Res Int 2016 26;2016:4872473. Epub 2016 Dec 26.

Faculdade de Farmácia, Universidade Federal da Bahia, 40170115 Salvador, BA, Brazil.

The course of infection is usually asymptomatic with a low discharge of rhabditoid larva in feces. However, the deleterious effects of alcohol consumption seem to enhance the susceptibility to infection, as shown by a fivefold higher strongyloidiasis frequency in alcoholics than in nonalcoholics. Moreover, the association between infection and alcoholism presents a risk for hyperinfection and severe strongyloidiasis. There are several possible mechanisms for the disruption of the host-parasite equilibrium in ethanol-addicted patients with chronic strongyloidiasis. One explanation is that chronic ethanol intake stimulates the hypothalamic-pituitary-adrenal (HPA) axis to produce excessive levels of endogenous cortisol, which in turn can lead to a deficiency in type 2 T helper cells (Th2) protective response, and also to mimic the parasite hormone ecdysone, which promotes the transformation of rhabditiform larvae to filariform larvae, leading to autoinfection. Therefore, when untreated, alcoholic patients are continuously infected by this autoinfection mechanism. Thus, the early diagnosis of strongyloidiasis and treatment can prevent serious forms of hyperinfection in ethanol abusers.
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http://dx.doi.org/10.1155/2016/4872473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5220430PMC
January 2017

Performance of microscopy and ELISA for diagnosing Giardia duodenalis infection in different pediatric groups.

Parasitol Int 2016 Dec 30;65(6 Pt A):635-640. Epub 2016 Aug 30.

Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, Brazil. Electronic address:

Techniques for Giardia diagnosis based on microscopy are usually applied as routine laboratory testing; however, they typically exhibit low sensitivity. This study aimed to evaluate Giardia duodenalis and other intestinal parasitic infections in different pediatric groups, with an emphasis on the comparison of Giardia diagnostic techniques. Feces from 824 children from different groups (diarrheic, malnourished, with cancer and from day care) were examined by microscopy and ELISA for Giardia, Cryptosporidium sp. and Entamoeba histolytica coproantigen detection. Giardia-positive samples from day-care children, identified by either microscopy or ELISA, were further tested by PCR targeting of the β-giardin and Gdh genes. Statistically significant differences (P<0.05) were observed when comparing the frequency of each protozoan among the groups. Giardia duodenalis was more frequent in day-care children and Cryptosporidium sp. in diarrheic and malnourished groups; infections by Entamoeba histolytica were found only in children with diarrhea. Considering positivity for Giardia by at least one method, ELISA was found to be more sensitive than microscopy (97% versus 55%). To examine discrepancies among the diagnostic methods, 71 Giardia-positive stool samples from day-care children were tested by PCR; of these, DNA was amplified from 51 samples (77.4%). Concordance of positivity between microscopy and ELISA was found for 48 samples, with 43 confirmed by PCR. Parasite DNA was amplified from eleven of the 20 Giardia samples (55%) identified only by ELISA. This study shows the higher sensitivity of ELISA over microscopy for Giardia diagnosis when a single sample is analyzed and emphasizes the need for methods based on coproantigen detection to identify this parasite in diarrheic fecal samples.
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http://dx.doi.org/10.1016/j.parint.2016.08.012DOI Listing
December 2016

Differences in the detection of Cryptosporidium and Isospora (Cystoisospora) oocysts according to the fecal concentration or staining method used in a clinical laboratory.

J Parasitol 2013 Dec 5;99(6):1002-8. Epub 2013 Jul 5.

Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, Bahia, Brazil, 40170-115.

Despite the availability of many parasitological methods for detection of Cryptosporidium and Isospora (Cystoisospora) belli in fecal samples, there are uncertainties about the accuracy of these techniques in laboratory practice. In this study, 27 formalin-fixed positive stool samples for Cryptosporidium and 15 for I. belli were analyzed by 2 concentration methods, sedimentation by centrifugation (SC) and formalin-ethyl acetate (FE), and by 3 tintorial techniques, modified Ziehl-Neelsen (ZN), safranin (SF), and auramine (AR). No significant differences were observed on Cryptosporidium identification between concentration methods, while a significantly higher number of I. belli oocysts (P < 0.0001) was detected in fecal smears concentrated by the SC than by the FE method. Fecal samples processed by FE produced a median oocyst loss to the fatty ring of 34.8% for Cryptosporidium and 45.4% for I. belli. However, FE concentration provided 63% of Cryptosporidium and 100% of I. belli slides classified as superior for microscopic examination. Regarding the efficiency of staining methods, a more significant detection of Cryptosporidium oocysts was observed in fecal smears stained by ZN (P < 0.01) or AR (P < 0.05) than by the SF method. Regular to high-quality slides for microscopic examination were mostly observed in fecal smears stained with AR or ZN for Cryptosporidium and with SF or ZN for I. belli. This study suggests a great variability in oocyst power detection by routine parasitological methods, and that the most frequent intestinal coccidians in humans have specific requirements for concentration and staining.
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http://dx.doi.org/10.1645/12-33.1DOI Listing
December 2013

Characterization of novel Leishmania infantum recombinant proteins encoded by genes from five families with distinct capacities for serodiagnosis of canine and human visceral leishmaniasis.

Am J Trop Med Hyg 2011 Dec;85(6):1025-34

Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.

To expand the available panel of recombinant proteins that can be useful for identifying Leishmania-infected dogs and for diagnosing human visceral leishmaniasis (VL), we selected recombinant antigens from L. infantum, cDNA, and genomic libraries by using pools of serum samples from infected dogs and humans. The selected DNA fragments encoded homologs of a cytoplasmic heat-shock protein 70, a kinesin, a polyubiquitin, and two novel hypothetical proteins. Histidine-tagged recombinant proteins were produced after subcloning these DNA fragments and evaluated by using an enzyme-linked immunosorbent assays with panels of canine and human serum samples. The enzyme-linked immunosorbent assays with different recombinant proteins had different sensitivities (67.4-93.0% and 36.4-97.2%) and specificities (76.1-100% and 90.4-97.3%) when tested with serum samples from Leishmania-infected dogs and human patients with VL. Overall, no single recombinant antigen was sufficient to serodiagnosis all canine or human VL cases.
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http://dx.doi.org/10.4269/ajtmh.2011.11-0102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3225146PMC
December 2011

Efficacy of parasitological methods for the diagnosis of Strongyloides stercoralis and hookworm in faecal specimens.

Acta Trop 2011 Dec 27;120(3):206-10. Epub 2011 Aug 27.

Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal da Bahia, Salvador, Brazil.

To compare the efficacy of stool examination for the detection of Strongyloides stercoralis and hookworm, a total of 634 stool samples from the routine laboratory service of the Pharmacia Faculty, Federal University of Bahia, Brazil, were examined by agar plate culture (APC), Baermann-Moraes and spontaneous sedimentation. The sensitivity of agar plate culture, calculated by combining results of all 3 methods, was 95% for S. stercoralis and 77.6% for hookwoorm. Moreover, APC had superior accuracy than Baermann-Moraes and spontaneous sedimentation for S. stercoralis and hookworm diagnosis, respectively. The S. stercoralis and hookworm positive samples from the laboratory routine, obtained after the previous analysis, along with those initially selected, were used to evaluate the concordance between microscopic examination and both the type of furrows left by larvae and the time for culture positivity using the APC method. Of 115 stool samples positive for S. stercoralis and 92 positive for hookworm, 110 (95.7%) and 89 (96.7%), respectively, had concordant results for furrows and morphological characteristics. The cumulative percentage of positivity increased to 94% by the third day of observation; at this time, only 19.6% of hookworm-positive samples had positive culture plates. Analyses of 74 S. stercoralis-positive stool samples stored at 4°C for 24, 48 and 72h showed the presence of larvae in 48.6%, 28.4% and 23% of samples, respectively when re-examined by the APC. As a definitive diagnosis of strongyloidiasis depends on the microscopic demonstration of parasites, increasing the sensitivity of the detection requires the use of different parasitological methods, including APC.
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http://dx.doi.org/10.1016/j.actatropica.2011.08.010DOI Listing
December 2011

Enhancement of experimental cutaneous leishmaniasis by Leishmania molecules is dependent on interleukin-4, serine protease/esterase activity, and parasite and host genetic backgrounds.

Infect Immun 2011 Mar 20;79(3):1236-43. Epub 2010 Dec 20.

Centro de Pesquisa Gonçalo Moniz, FIOCRUZ, Rua Waldemar Falcão 121, 40296-710 Salvador, Bahia, Brazil.

Most inbred strains of mice, like the BALB/c strain, are susceptible to Leishmania amazonensis infections and resistant to Leishmania braziliensis infections. This parasite-related difference could result from the activity of an L. amazonensis-specific virulence factor. In agreement with this hypothesis, it is shown here that the intravenous injection of BALB/c mice with L. amazonensis amastigote extract (LaE) but not the L. braziliensis extract confers susceptibility to L. braziliensis infection. This effect was associated with high circulating levels of IgG1 anti-L. amazonensis antibodies and with an increase in interleukin-4 (IL-4) production and a decrease in gamma interferon production by draining lymph node cells. Moreover, the effect was absent in IL-4-knockout mice. The biological activity in the LaE was not mediated by amphiphilic molecules and was inhibited by pretreatment of the extract with irreversible serine protease inhibitors. These findings indicate that the LaE contains a virulence-related factor that (i) enhances the Leishmania infection by promoting Th2-type immune responses, (ii) is not one of the immunomodulatory Leishmania molecules described so far, and (iii) is either a serine protease or has an effect that depends on that protease activity. In addition to being Leishmania species specific, the infection-enhancing activity was also shown to depend on the host genetic makeup, as LaE injections did not affect the susceptibility of C57BL/6 mice to L. braziliensis infection. The identification of Leishmania molecules with infection-enhancing activity could be important for the development of a vaccine, since the up- or downmodulation of the immune response against a virulence factor could well contribute to controlling the infection.
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http://dx.doi.org/10.1128/IAI.00309-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3067519PMC
March 2011

A strategy for identifying serodiagnostically relevant antigens of Leishmania or other pathogens in genetic libraries.

Biologicals 2007 Mar 31;35(1):51-4. Epub 2006 Mar 31.

Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Rua Valdemar Falcão 121, 40295-001, Salvador, Brazil.

Different individuals, when infected with the same parasite, rarely produce antibodies against the same set of antigens. Indeed, unless a particular antigen happens to be recognized by antibodies in all individuals, the use of a single antigen in the serodiagnosis of parasitic diseases leads, invariably, to false-negative results. A straightforward method for pin-pointing, in genetic libraries, the precise antigens that would increase serodiagnostic assay sensitivities is presented. The method is based on the utilization of sera that produced false-negative results against previously available antigens. Employing this false-negative serum-selection methodology for the identification of new Leishmania infantum recombinant antigens (rAgs), the sensitivity of a dipstick assay for anti-Leishmania antibodies in a panel of sera from patients with visceral leishmaniasis was increased from 83.3% to 98.1%, without affecting its specificity, by the inclusion of a fifth and a sixth L. infantum rAg.
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http://dx.doi.org/10.1016/j.biologicals.2006.01.005DOI Listing
March 2007

Sub-clinical infection as an effective protocol for obtaining anti-Leishmania chagasi amastigote antibodies of different animal species.

Vet Immunol Immunopathol 2004 Jun;99(3-4):135-41

Instituto de Ciências da Saúde, Universidade Federal da Bahia, Avenida Reitor Miguel Calmon, s/n, Canela, 40.110-100 Salvador, Bahia, Brazil.

This work aims at identifying an effective protocol to raise anti-Leishmania chagasi amastigote antibodies in different animal species. Protocols of immunization by subcutaneous injections of L. chagasi promastigote and amastigote lysates or by either intravenous or subcutaneous inoculation of live metacyclic promastigotes were assessed in mice, rabbits, and dogs. The immunization with live promastigotes produced a strong humoral immune response against L. chagasi amastigotes in all three animal species. The sera from animals immunized with the promastigote lysate did not react with amastigotes and, conversely, the sera from mice immunized with the amastigote lysate did not react with promastigotes. Taken all data together, the immunization through infection with metacyclic promastigotes was considered the most satisfactory way to immunize animals for obtaining anti-amastigote and anti-promastigote antibodies, since it did not only allowed the obtention of antibody against the two forms of the parasite, but it is also cheap, less laborious than carrying out the purification of amastigotes from infected tissues and avoid the use of a large number of hamsters for obtention the amastigotes, necessary to produce the immunogenic lysates. Furthermore, this immunization protocol was comparable to the amastigote lysate immunization protocol for the obtaining of mouse monoclonal antibodies (mAbs).
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http://dx.doi.org/10.1016/j.vetimm.2004.01.013DOI Listing
June 2004
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