PCR for diagnosis and follow-up of two cases of disseminated toxoplasmosis after kidney grafting

Effective factors in the pathogenesis of Toxoplasmagondii

Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite in humans and animals. It infects about 30 % of the human population worldwide and causes potentially fatal diseases in immunocompromised hosts and neonates. For this study, five English-language databases (ScienceDirect, ProQuest, Web of Science, PubMed, and Scopus) and the internet search engine Google Scholar were searched. This review was accomplished to draw a global perspective of what is known about the pathogenesis of T. gondii and various factors affecting it. Virulence and immune responses can influence the mechanisms of parasite pathogenesis and these factors are in turn influenced by other factors. In addition to the host's genetic background, the type of Toxoplasma strain, the routes of transmission of infection, the number of passages, and different phases of parasite life affect virulence. The identification of virulence factors of the parasite could provide promising insights into the pathogenesis of this parasite. The results of this study can be an incentive to conduct more intensive research to design and develop new anti-Toxoplasma agents (drugs and vaccines) to treat or prevent this infection. In addition, further studies are needed to better understand the key agents in the pathogenesis of T. gondii.

Does Toxoplasma gondii infection impact liver transplantation outcomes? A systematic review

PURPOSE

Approximately one-third of the world's population has Toxoplasma gondii infection, and one of the main routes of transmission is organ transplantation. The aim of this study was to evaluate the impact of Toxoplasma infection on liver transplantation patients.

METHODOLOGY

We searched PubMed, Lilacs, Medline, Science direct, Scielo, Ebsco, Springer, Wiley, Ovid and Google Scholar for reports published up to June 2017, and a systematic review was performed.

RESULTS

Twenty cases were analysed before and after liver transplantation. Primary and reactivated infections were investigated. Before transplantation, positive IgG antibodies were the predominant serological markers in donors and recipients: 40 % (D+/R-), 20 % (D+/R+) and 20 % (D-/R+). IgM was present in only 5 % of the donors (D+/R-). In four cases, the serological markers were not specified or were negative (D?/R? or D?/R-). After transplantation, IgM anti-Toxoplasma antibodies were found in 30 % of the recipients, and in 67 % of the seronegative recipients the presence of Toxoplasma DNA or tachyzoites was reported, suggesting a primary infection. Clinical symptoms were meningitis, massive cerebral oedema, encephalitis and seizures. Treatment was administered in 70 % of the patients, and 40 % died after presenting symptoms associated with Toxoplasma infection.

CONCLUSIONS

Although we review Toxoplasma infection and liver transplantation cases, problems associated with the parasite may be greater than identified. Hence, follow-up studies on Toxoplasma infection in liver transplantation patients are recommended.

Serological diagnosis of Toxoplasma gondii infection: Recommendations from the French National Reference Center for Toxoplasmosis

Toxoplasmosis manifests no clinical signs in 80% of cases in immunocompetent patient, causing immunization characterized by the persistence of cysts, particularly in brain, muscles, and retina. Assessing the serological status, based on testing for serum toxoplasma IgG and IgM antibodies, is essential in cases that are increasingly at risk for the more severe disease forms, such as congenital or ocular toxoplasmosis. This disease also exposes immunosuppressed patients to reactivation, which can lead to more widespread forms and increased mortality. By interpreting the serological results, we can estimate the risk of contamination or reactivation and define appropriate prophylactic and preventive measures, such as hygienic and dietetic, therapeutic, biological, and clinical follow-up, according to the clinical context. We hereby propose practical approaches based on serological data, resulting from a consensus of a group of experts from the French National Reference Center Network for Toxoplasmosis, according to both routine and specific clinical situations.

Parasitic infections in solid organ transplant recipients

Parasitic diseases are rare infections after a solid organ transplant (SOT). Toxoplasmosis, Trypanosoma cruzi, and visceral leishmanias are the 3 main opportunistic protozoal infections that have the potential to be lethal if not diagnosed early and treated appropriately after SOT. Strongyloides stercoralis is the one helminthic disease that is life-threatening after transplant. This review addresses modes of transmission, methods of diagnosis, and treatment of the most serious parasitic infections in SOT. The role of targeted pretransplant screening of the donor and recipient for parasitic diseases is also discussed.

Recombinant SAG1 Antigen to Detect Toxoplasma gondii Specific Immunoglobulin G in Human Sera by ELISA Test

BACKGROUND

Although some serological tests for the detection of Toxoplasma gondii-specific immunoglobulin are commercially available, better diagnostic tools are needed. The aim of present study was to evaluate the usefulness of the recombinant Toxoplasma gondii SAG1 antigen for the recognition of toxoplasmosis by ELISA.

METHODS

This study was conducted in Cellular and Molecular Biology Research Centers, Shahid Beheshti University, M.C., Tehran, Iran in 2008-2009. Surface antigen 1 (SAG1), a tachyzoite stage-specific protein, was subcloned into an expression vector and was subsequently transformed into BL21 (DE3) pLysS competent bacterial cells. After inducing expression of the recombinant antigen, the protein product was purified using Ni-affinity chromatography. The immunoreactivity of recombinant SAG1 (rSAG1) was analyzed by SDS-PAGE and western blotting. The reactivity of the rec-SAG1 protein was evaluated using an ELISA.

RESULT

Sensitivity and specificity of the generated recombinant-ELISA (rec-ELISA) compared to a commercially available ELISA (com-ELISA) were 88.4% and 88%, respectively.

CONCLUSION

Recombinant SAG1 produced in E. coli is a promising antigen that can be used in diagnostic assays for the detection of specific antibodies against T. gondii.

Prevention of toxoplasmosis in transplant patients

Toxoplasmosis is a life-threatening opportunistic infection that affects haematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients. Its incidence in these patients is closely related to the prevalence of toxoplasmosis in the general population, which is high in Europe. In SOT recipients, toxoplasmosis results mainly from transmission of the parasite with the transplanted organ from a Toxoplasma-seropositive donor to a Toxoplasma-seronegative recipient. This risk is high in cases of transplantation of organs that are recognized sites of encystation of the parasite, e.g. the heart, and is markedly lower in other SOT recipients. Clinical symptoms usually occur within the first 3 months after transplantation, sometimes as early as 2 weeks post transplant, and involve febrile myocarditis, encephalitis or pneumonitis. In HSCT recipients, the major risk of toxoplasmosis results from the reactivation of a pre-transplant latent infection in seropositive recipients. The median point of disease onset is estimated at 2 months post transplant, with <10% of cases occurring before 30 days and 15-20% later than day 100. Toxoplasmosis usually manifests as encephalitis or pneumonitis, and frequently disseminates with multiple organ involvement. Diagnosis of toxoplasmosis is based on the demonstration of parasites or parasitic DNA in blood, bone marrow, cerebrospinal fluid, bronchoalveolar lavage fluid or biopsy specimens, and serological tests do not often contribute to the diagnosis. For prevention of toxoplasmosis, serological screening of donors and recipients before transplantation allows the identification of patients at higher risk of toxoplasmosis, i.e. seropositive HSCT recipients and mismatched (seropositive donor/seronegative recipients) SOT recipients. Preventing toxoplasmosis disease in those patients presently relies on prophylaxis via prescription of co-trimoxazole.

Unusual presentation of primary toxoplasmosis infection in a kidney-transplant patient complicated by an acute left-ventricular failure

Although primary toxoplasmosis is a rare event following kidney transplantation, it can be life threatening. This report describes this complication. The patient presented with high-grade fever, haemolytic anaemia and haemophagocytic-syndrome-related pancytopaenia. Toxoplasma gondii diagnosis was ascertained by blood and bone-marrow PCR assays. After 6 weeks with Clindamycin plus pyrimethamine therapies and despite negativation of T. gondii blood PCR assay, the patient developed left-ventricular failure. After adding sulfamethoxazole/ trimethoprim, ramipril, digoxine, bisoprolol and spironolactone, he progressively recovered. Anti-T. gondii therapy was continued for 6 months. Four years later he received a third kidney allograft: at that time anti-T. gondii antibodies had become negative. The outcome was uneventful despite immunosuppression but with inclusion of sulfamethoxazole/trimethoprim prophylaxis. More than 3 years after the third kidney transplantation the patient has had no toxoplasmosis reactivation. This case report highlights that T. gondii can be the cause of myocarditis in a renal transplant recipient.

Diagnosis of pulmonary infection with Toxoplasma gondii in immunocompromised HIV-positive patients by real-time PCR

The aim of the study presented here was to evaluate the use of PCR for improving the diagnosis of Toxoplasma gondii infection in immunocompromised hosts. Three hundred thirty-two bronchoalveolar lavage (BAL) fluid samples were analyzed by real-time PCR targeting a 529 bp element of T. gondii. In positive samples, the genotype of the parasite was determined by sequence analysis of the GRA6 gene. Positive results were achieved for 2% (7/332) of the samples tested. Genotyping was possible in two samples and revealed GRA6 type II T. gondii. PCR for detecting T. gondii in BAL samples should be performed in all immunosuppressed HIV-positive patients with symptoms of a systemic infection of unknown etiology. Trimethoprim-sulfamethoxazole prophylaxis does not exclude concomitant infection with T. gondii.

First case of toxoplasmosis following small bowel transplantation and systematic review of tissue-invasive toxoplasmosis following noncardiac solid organ transplantation

BACKGROUND

Toxoplasmosis prophylaxis is standard following heart and heart lung transplantation, when an increased risk of allograft transmitted Toxoplasma is well-recognized. In contrast, prophylaxis and routine serologic evaluation of donors and recipients for Toxoplasma in noncardiac solid organ transplantation (SOT) is not recommended. We report the first case of disseminated toxoplasmosis following small bowel transplantation, presumably transmitted via the transplanted intestine and systematically review reported cases of toxoplasmosis in noncardiac SOT recipients to determine if current guidelines should be reconsidered.

METHODS

Systematic MEDLINE review was performed for tissue invasive toxoplasmosis in noncardiac SOT recipients and analysis of clinical features, serologic status, and treatment regimens with respect to mortality.

RESULTS

Fifty-two cases of toxoplasmosis in noncardiac SOT recipients were identified. Eighty-six percent developed disease within 90 days of transplantation. Presentation was nonspecific and consisted of fever (77%), respiratory distress (29%), neurologic manifestations (29%), and bone marrow suppression (26%). Multivariate analyses demonstrated that localized disease (odds ratio [OR]=37.36, 95% CI 1.85-754.85), treatment received (OR=1.814, 95% CI 1.193-3.480) and donor and recipient serostatus (OR=1.39, 95% CI 1.068-1.815) were predictors of survival. High-risk recipients (donor seropositive/recipient seronegative) developed disease earlier (16 days vs. 31 days P=0.002) and were less likely to survive (OR=0.14, 95% CI 0.03-0.69) than standard-risk recipients.

CONCLUSIONS

Toxoplasmosis is recognized following noncardiac SOT. Reduction of morbidity and mortality necessitates knowledge of donor and recipient Toxoplasma serostatus, prophylaxis, early diagnosis, and treatment. The findings support a reconsideration of pretransplantation evaluation and prophylaxis strategies in SOT recipients.

Toxoplasmosis after renal transplantation: implications of a missed diagnosis

We describe a renal transplant patient with a primary Toxoplasma gondii infection presenting as pneumonitis, with subsequent chorioretinitis and encephalitis. The diagnostic challenges of T. gondii infection in immunocompromised patients are discussed.

Disseminated toxoplasmosis with pulmonary involvement after heart transplantation

We report a case of pulmonary toxoplasmosis after heart transplant despite the prophylactic anti-toxoplasmic treatment that was given but was not sufficient to prevent toxoplasmosis. However, the patient survived thanks to early diagnosis confirmed by polymerase chain reaction on blood and by serological techniques, and early treatment.

Fast dipstick dye immunoassay for detection of immunoglobulin G (IgG) and IgM antibodies of human toxoplasmosis

A dipstick dye immunoassay (DDIA) was developed to detect immunoglobulin G (IgG) or IgM antibodies of toxoplasmosis infection in humans. The assays employ a blue colloidal dye particles (D-1) conjugated to sheep anti-human IgG and rabbit anti-human IgM as the visualizing agents and a soluble antigen of tachyzoites of Toxoplasma gondii strain RH (TSA) as the detective antigen. The mixture of dye-labeled anti-human antibody-special human antibody was captured by TSA onto a nitrocellulose membrane dipstick by means of immunochromatography. The assays are rapid (the whole test can be completed within 15 min), simple, and cheap, and they don't require any equipment. They are sensitive and specific for the detection of anti-Toxoplasma IgG or IgM antibodies and generally agree closely with the results from the enzyme-linked immunosorbent assay. The assays are especially suitable for field applications.

High yield expression and single-step purification of Toxoplasma gondii SAG1, GRA1, and GRA7 antigens in Escherichia coli

This report describes a simple, highly efficient and reproducible method for obtaining large quantities of highly pure recombinant Toxoplasma gondii antigens, which can be used for diagnostic application. The obtained T. gondii SAG1, GRA1, and GRA7 antigens (as fusion proteins), expressed in Escherichia coli, contained polyhistidine tags at the N- and C-ends that allowed single-step isolation by metal-affinity chromatography on Ni(2+)-IDA-Sepharose columns. The immunoreactivity of the recombinant antigens was tested in an enzyme-linked immunosorbent assay (ELISA) format for potential application in the serodiagnosis of T. gondii infection.

Quantitative detection of Toxoplasma gondii DNA in human body fluids by TaqMan polymerase chain reaction

OBJECTIVE

A new quantitative polymerase chain reaction (real-time PCR) was designed to detect Toxoplasma DNA in human body fluid samples.

METHODS

Real-time fluorescence detection of amplification product formation on the basis of the TaqMan-System was established with Toxoplasma 18S rDNA as a target gene.

RESULTS

The method provides a high sensitivity comparable to conventional nested PCR procedures and generates quantitative data when detecting toxoplasmic DNA in human blood, cerebrospinal or amniotic fluid. Moreover, data were obtained investigating blood samples from an immunocompromised patient with reactivated toxoplasmosis after allogeneic bone marrow transplantation, monitoring the therapeutic effect.

CONCLUSIONS

The potential application of this method to detect Toxoplasma DNA in body fluids and to follow the development of parasitemia under therapy could be demonstrated.