Disseminated toxoplasmosis, resulting from infection of allograft, after orthotopic liver transplantation: usefulness of quantitative PCR

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.

Metagenomic Next-generation Sequencing May be a Tool for Timely Diagnosis of Seronegative and Primary Toxoplasma Infection After Allogeneic Hematopoietic Stem Cell Transplantation: A Case Report and Literature Review

We report a case of Toxoplasma gondii ( T. gondii ) antibody seronegativity in a 14-year-old boy with a primary infection of T. gondii after allogeneic hematopoietic stem cell transplantation for acute T-cell lymphoblastic leukemia who was rapidly diagnosed through metagenomic next-generation sequencing of peripheral blood as well as clinical manifestations. He was successfully cured with timely administration of trimethoprim-sulfamethoxazole due to early diagnosis.

Prevalence of Toxoplasma gondii 36-KDa antigen and chronic Hepatitis C: another evidence of an Association

In chronic hepatitis C (CHC), Toxoplasma gondii infection can lead to more severe diseases and is capable of changing the disease course. Former studies were concerning anti-T. gondii IgG/IgM seroprevalence in CHC patients regardless the antigenic proteins that are associated with active infection. Therefore, this study aimed to evaluate association between prevalence of 36-KDa T. gondii antigen (TAg) and both CHC progression and liver and viral biochemical parameters. One hundred-twenty five CHC patients (65 with fibrosis and 60 with cirrhosis) and forty healthy controls constituted this study. Demographics and clinical data were collected. Both TAg and HCV-NS4 were identified using ELISA. In contrast to healthy controls (0%), both seropositivity (P = 0.043) and mean serum level (P = 0.025) of TAg were higher in cirrhotic patients (43.3 %; 1.2 ± 0.2 ng/mL) compared to fibrotic patients (26.2 %; 0.7 ± 0.1 ng/mL). T. gondii infection was significantly (P < 0.05) associated with liver and viral biochemical parameters including increased ALT and AST activities, total bilirubin and AFP levels and decreased albumin and platelets count levels. Interestingly, TAg positivity were associated with elevated HCV-NS4 level compared to negative TAg patients (212.5 ± 25.3 vs. 133.9 ± 17.4 µg/mL (P = 0.026); r = 0.559 (P < 0.0001)). In conclusion, this study highlighted association between T. gondii parasitemia and CHC progression since TAg was more prevalent among cirrhotic than fibrotic patients and healthy controls. The presence of TAg was associated with impaired liver functions and increased HCV-NS4 levels. Further studies are needed to define the mechanism of this association.

Molecular diagnosis of toxoplasmosis: recent advances and a look to the future

INTRODUCTION

Toxoplasmosis is a globally distributed parasitic infection that can be particularly severe when opportunistic or congenital. Its diagnosis requires accurate and rapid techniques that rely mainly on serology and molecular methods.

AREAS COVERED

The aim of this review was to discuss the positioning of the molecular diagnosis of toxoplasmosis according to the different clinical situations possibly resulting from infection with T. gondii, and to detail recent developments in this technique. The English and French literature were searched with the following keywords: 'Toxoplasmosis', "Molecular diagnosis" and 'PCR'.

EXPERT OPINION

Molecular techniques have revolutionized the diagnosis of toxoplasmosis, and practices have considerably evolved over the past decades. However, there is still a high degree of inter-laboratory heterogeneity which impairs comparisons between results and studies. Efforts to standardize practices are underway.

Serology for Toxoplasma in Immunocompromised Patients: Still Useful?

Toxoplasmosis represents one of the most common comorbidity factors in solid organ or hematopoietic stem cell transplant recipients as well as in other immunocompromised patients. In the past decades, availability and performance of molecular tools for the diagnosis or the exclusion of toxoplasmosis in these patients have greatly improved. However, if accurately used, serology remains a complementary and essential diagnostic tool for physicians and medical parasitologists for the prevention and management of toxoplasmosis in immunocompromised patients as well. It is required for determination of the immunological status of patients against Toxoplasma. It also helps diagnose and monitor complex cases of opportunistic Toxoplasma infection in immunocompromised patients. New perspectives are available to further enhance their yield and ease of use.

Multicentric Evaluation of the Bio-Evolution Toxoplasma gondii Assay for the Detection of Toxoplasma DNA in Immunocompromised Patients

PCR-based methods are a key tool for the diagnosis of toxoplasmosis in immunocompromised patients. Laboratory-developed protocols lack standardization. This study aimed to assess the performances of a commercial kit for the detection of Toxoplasma DNA in different specimens drawn from immunocompromised patients. This multicentric retrospective study included 227 DNA specimens (157 blood specimens, 22 bronchoalveolar fluid [BALF] specimens, 39 cerebrospinal fluid [CSF] specimens, and 9 miscellaneous specimens) collected between 2010 and 2015 from 126 immunocompromised patients. The specimens were selected based on previous laboratory-developed quantitative PCR (qPCR) analyses targeting either the rep529 element or the B1 gene, and the results were classified as positive, negative, and "negative of interest," where the latter was defined as representing either the last specimen with a negative result before a positive one or the first with a negative result following a positive result(s). All specimens were secondary tested using the Bio-Evolution Toxoplasma DNA assay targeting the T. gondii rep529 element. We found a 95.6% concordance rate for qualitative results obtained with laboratory-developed qPCR techniques and the commercial kit. The rate reached 99.3% in comparisons of rep529-based laboratory-developed PCR methods and the commercial kit. The quantifications obtained with the commercial kit and the rep529 laboratory-developed PCRs were in very good agreement. Sensitivity and specificity of the commercial kit were calculated at 98.8% and 100%, respectively. The Bio-Evolution Toxoplasma DNA assay appears to be a valuable method for the detection of Toxoplasma DNA in blood, BALF, and CSF specimens from immunocompromised patients.

Toxoplasmosis in the non-orthotopic heart transplant recipient population, how common is it? Any indication for prophylaxis?

PURPOSE OF REVIEW

Unlike in orthotopic heart transplant (OHT) setting where toxoplasma prophylaxis is a standard practice in pretransplant toxoplasma seronegative recipients who have received donor hearts from seropositive donors (D+/R-), there is no consensus regarding prophylaxis in non-OHT recipients.

RECENT FINDINGS

The incidence of toxoplasma disease in non-OHT recipients is less than 1% but its true burden is underestimated. Among 31 cases of toxoplasma disease reported from 2004 through 2017, renal and liver transplant recipients comprised of 90% of cases. A total of 94% of 18 recipients with known pretransplant serology were seronegative recipients (mostly D+/R-). Out of 16 recipients with adequate information, 10 (63%) and five (31%) were deemed to be donor derived and nondonor-derived primary toxoplasmosis respectively. Tissue invasive reactivation was uncommon. Almost all cases were described in patients not on prophylaxis at the time of presentation. Universal screening of donor/recipient toxoplasma serology for risk stratification is beneficial as illustrated by reports of fatal cases of toxoplasmosis due to unavailability of positive donor serology results.

SUMMARY

Toxoplasma disease in non-OHT predominantly occurs in pretransplant seronegative recipients- mostly in D+/R- group and is rare in seropositive recipients. Posttransplant prophylaxis should be targeted against the high-risk D+/R- group and should be considered in seropositive recipients in whom unusually high immunosuppression is implemented. Toxoplasma serologies and PCR should be used in combination for the diagnosis of toxoplasmosis in non-OHT patients.

Infectious Disease Transmission in Solid Organ Transplantation: Donor Evaluation, Recipient Risk, and Outcomes of Transmission

In 2016, the Transplantation Society of Australia and New Zealand, with the support of the Australian Government Organ and Tissue authority, commissioned a literature review on the topic of infectious disease transmission from deceased donors to recipients of solid organ transplants. The purpose of this review was to synthesize evidence on transmission risks, diagnostic test characteristics, and recipient management to inform best-practice clinical guidelines. The final review, presented as a special supplement in Transplantation Direct, collates case reports of transmission events and other peer-reviewed literature, and summarizes current (as of June 2017) international guidelines on donor screening and recipient management. Of particular interest at the time of writing was how to maximize utilization of donors at increased risk for transmission of human immunodeficiency virus, hepatitis C virus, and hepatitis B virus, given the recent developments, including the availability of direct-acting antivirals for hepatitis C virus and improvements in donor screening technologies. The review also covers emerging risks associated with recent epidemics (eg, Zika virus) and the risk of transmission of nonendemic pathogens related to donor travel history or country of origin. Lastly, the implications for recipient consent of expanded utilization of donors at increased risk of blood-borne viral disease transmission are considered.

Prevalence of Toxoplasma gondii Antibodies and DNA in Iranian HIV Patients

Background & Objective:

Toxoplasma gondii infection has public health importance and can lead to serious diseases in immunosuppressed patients, such as HIV cases. Appropriate control of T. gondii infection in HIV patients requires information about the prevalence of T. gondii antibodies and DNA in different population. In this study, we aimed to determine the prevalence of Toxoplasma gondii antibodies and DNA in HIV patients in Tehran, Iran.

Methods:

A total of 149 HIV patients from the Iranian Research Center for HIV/AIDS, Tehran, Iran were enrolled in the study. Anti-Toxoplasma IgG and IgM were detected by ELISA and T. gondii DNA was evaluated by PCR and quantita- tive real-time PCR. IgG positive samples were also assessed for their avidity.

Results:

Anti-Toxoplasma IgG and IgM were positive in 46.3% and 2.7% of cases respectively. 92.7% of our patients showed past infection and 4.3% revealed recently acquired toxoplasmosis based on their IgG avidity test. T. gondii DNA was not detected by PCR but real-time PCR results showed DNA in 4.7% of total patients and 13.1% of the IgG seropositive cases.

Conclusion:

Our findings indicated that latent toxoplasmosis was relatively prevalent in our study population, but new

T. gondii infection had low prevalence. Almost half of our patients were IgG negative and at risk of acquiring toxoplasma infection. Low copy numbers of DNA were detected in 4.7% of the cases without any clinical manifestation. Therefore, detection and monitoring of anti-Toxoplasma antibodies and DNA in HIV patients is substantial to estimate the risk of reactivation and new infection.

Frequency of sero-positivity in household members of the patients with positive toxoplasma serology

OBJECTIVE

Toxoplasma gondii is cause of a wide variety of infections in human. The aim of this study was; to evaluate the frequency of sero-positivity of the members in a family with a positive serologic person.

METHODS

A case-control study with 170 enrolled units which was conducted in Iran in 2017. The units were settled into two group: I: the family members of seropositive individuals and II: the family members of seronegative individuals. The level of IgG and IgM anti-toxoplasma antibodies were evaluated by ELISA qualitative manner in both groups.

RESULTS

Frequency of individuals with positive serology was 52.9% and 34.1% in group I and II, respectively (P value = 0.01).

CONCLUSIONS

Clusters of toxoplasma infection would be an event in the family members. Therefore evaluation of the family members (especially high risk persons) of a patient may be necessary.

Solid Organ Transplant and Parasitic Diseases: A Review of the Clinical Cases in the Last Two Decades

The aim of this study was to evaluate the occurrence of parasitic infections in solid organ transplant (SOT) recipients. We conducted a systematic review of literature records on post-transplant parasitic infections, published from 1996 to 2016 and available on PubMed database, focusing only on parasitic infections acquired after SOT. The methods and findings of the present review have been presented based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist. From data published in the literature, the real burden of parasitic infections among SOT recipients cannot really be estimated. Nevertheless, publications on the matter are on the increase, probably due to more than one reason: (i) the increasing number of patients transplanted and then treated with immunosuppressive agents; (ii) the “population shift” resulting from immigration and travels to endemic areas, and (iii) the increased attention directed to diagnosis/notification/publication of cases. Considering parasitic infections as emerging and potentially serious in their evolution, additional strategies for the prevention, careful screening and follow-up, with a high level of awareness, identification, and pre-emptive therapy are needed in transplant recipients.

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.

Pulmonary toxoplasmosis in immunocompromised patients with interstitial pneumonia: a single-centre prospective study assessing PCR-based diagnosis

AIMS

Pulmonary toxoplasmosis has become a very rare parasitic infection since the advent of highly active antiretroviral therapies. It is generally diagnosed by the direct microscopic observation of Toxoplasma gondii tachyzoites in bronchoalveolar lavage fluid (BALF). The aim of this study was to assess possible improvements in diagnostic performance associated with the use of real-time PCR.

METHODS

This prospective study was carried out on BALFs obtained from immunocompromised patients over a 2-year period. We systematically compared the results of conventional staining with those of molecular detection.

RESULTS

Two cases of pulmonary toxoplasmosis were diagnosed for a total of 336 samples. PCR did not detect any additional cases and was more time-consuming than conventional staining.

CONCLUSIONS

Conventional staining is a reliable technique and is probably the most appropriate method for experienced microbiology laboratories, whereas T. gondii-specific PCR may be useful for laboratories with less experience in parasitology.

TRIAL REGISTRATION NUMBER

2015_030, May 27th 2015.

Molecular diagnosis of toxoplasmosis in immunocompromised patients: a 3-year multicenter retrospective study

Toxoplasmosis is a life-threatening infection in immunocompromised patients (ICPs). The definitive diagnosis relies on parasite DNA detection, but little is known about the incidence and burden of disease in HIV-negative patients. A 3-year retrospective study was conducted in 15 reference laboratories from the network of the French National Reference Center for Toxoplasmosis, in order to record the frequency of Toxoplasma gondii DNA detection in ICPs and to review the molecular methods used for diagnosis and the prevention measures implemented in transplant patients. During the study period, of 31,640 PCRs performed on samples from ICPs, 610 were positive (323 patients). Blood (n = 337 samples), cerebrospinal fluid (n = 101 samples), and aqueous humor (n = 100 samples) were more frequently positive. Chemoprophylaxis schemes in transplant patients differed between centers. PCR follow-up of allogeneic hematopoietic stem cell transplant (allo-HSCT) patients was implemented in 8/15 centers. Data from 180 patients (13 centers) were further analyzed regarding clinical setting and outcome. Only 68/180 (38%) patients were HIV(+); the remaining 62% consisted of 72 HSCT, 14 solid organ transplant, and 26 miscellaneous immunodeficiency patients. Cerebral toxoplasmosis and disseminated toxoplasmosis were most frequently observed in HIV and transplant patients, respectively. Of 72 allo-HSCT patients with a positive PCR result, 23 were asymptomatic; all were diagnosed in centers performing systematic blood PCR follow-up, and they received specific treatment. Overall survival of allo-HSCT patients at 2 months was better in centers with PCR follow-up than in other centers (P < 0.01). This study provides updated data on the frequency of toxoplasmosis in HIV-negative ICPs and suggests that regular PCR follow-up of allo-HSCT patients could guide preemptive treatment and improve outcome.

Frequency of Toxoplasma gondii in HIV Positive Patients from West of Iran by ELISA and PCR

BACKGROUND

Toxoplasma gondii, the obligate intracellular parasite is life threatening in AIDS patients. Diagnosis of toxoplasmosis is based on serological methods especially increasing of IgM and IgG titers, but finding of parasite or its components (antigenemia) may be beneficial method in order to detection of acute toxoplasmosis in immunocompromised patients.

METHODS

Ninety-four serum samples from HIV positive patients were collected from Sanandaj, Kordistan west of Iran. These patients were lived in Sanandaj of whom 26 were prisoners infected with HIV virus in prison. Toxoplasma gondii antibodies were determined by IgG ELISA. T. gondii antigen was identified by capture-ELISA. PCR was performed on samples with T. gondii antigenemia. CD4+ T cells counts had been determined by flowcytometry and were obtained from records of each patient.

RESULTS

Among the examined HIV seropositive individuals, 19.1% (18/94) and 5.3% (5/94) were positive for Toxoplasma-IgG and antigenemia, respectively. Besides, one of the samples was positively detected by PCR method. Mean age of participants was 37.9 ± 9.5 year. Prevalence of IgG antibody and antgenemia was higher in age group of 40-50 years old. The Mean of CD4+ T cells counts of participants (total of HIV+ patients, IgG positive patients and patients with antigenemia) was 699.2 ± 345.2, 655.1 ± 237.9 and 620.2 ± 215.1 respectively.

CONCLUSION

Capture-ELISA and PCR could confirm the T. gondii acute infection in HIV positive patients. For precise diagnosis of acute toxoplasmosis in HIV positive patient, performance of more studies based on more sensitive types of PCR is suggested.

Infections of the Liver

The portal vein carries blood from the gastrointestinal tract to the liver and in so doing carries microbes as well. The liver may therefore be involved in infections with a myriad number of microbial organisms. While some of these infections most commonly occur in the immunocompromised host, others affect the immune competence. Hepatic infections may be primary in nature or secondary, as part of systemic or contagious disease. The purpose of this chapter is to provide a brief overview of the various infections of the liver in the pediatric patient.

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.

Epidemiology of and diagnostic strategies for toxoplasmosis

The apicomplexan parasite Toxoplasma gondii was discovered a little over 100 years ago, but knowledge of its biological life cycle and its medical importance has grown in the last 40 years. This obligate intracellular parasite was identified early as a pathogen responsible for congenital infection, but its clinical expression and the importance of reactivations of infections in immunocompromised patients were recognized later, in the era of organ transplantation and HIV infection. Recent knowledge of host cell-parasite interactions and of parasite virulence has brought new insights into the comprehension of the pathophysiology of infection. In this review, we focus on epidemiological and diagnostic aspects, putting them in perspective with current knowledge of parasite genotypes. In particular, we provide critical information on diagnostic methods according to the patient's background and discuss the implementation of screening tools for congenital toxoplasmosis according to health policies.

Risk factors, clinical features, and outcomes of toxoplasmosis in solid-organ transplant recipients: a matched case-control study

BACKGROUND

Solid-organ transplant (SOT) recipients are considered to be at increased risk for toxoplasmosis. However, risk factors for this infection have not been assessed. The aim of this study was to determine the risk factors, clinical features, and outcomes of toxoplasmosis in SOT recipients.

METHODS

A multicenter, matched case-control study (1:2 ratio) was conducted between 2000 and 2009. Control subjects were matched for center, transplant type, and timing. Cases were identified from the hospitals' microbiology and transplantation program databases. Logistic regression was performed to identify independent risk factors.

RESULTS

Twenty-two cases (0.14%) of toxoplasmosis were identified among 15 800 SOTs performed in 11 Spanish hospitals, including 12 heart, 6 kidney, and 4 liver recipients. Diagnosis was made by seroconversion (n = 17), histopathologic examination (n = 5), polymerase chain reaction (n = 2), and autopsy (n = 2). In a comparison of case patients with 44 matched control subjects, a negative serostatus prior to transplantation was the only independent risk factor for toxoplasmosis (odds ratio, 15.12 [95% confidence interval, 2.37-96.31]; P = .004). The median time to diagnosis following transplantation was 92 days. Primary infection occurred in 18 (81.8%) cases. Manifestations included pneumonitis (n = 7), myocarditis (n = 5), brain abscesses (n = 5), chorioretinitis (n = 3), lymph node enlargement (n = 2), hepatosplenomegaly (n = 2), and meningitis (n =1). Five patients (22.7%) had disseminated disease. Crude mortality rate was 13.6% (3 of 22 patients).

CONCLUSIONS

Although uncommon, toxoplasmosis in SOT patients causes substantial morbidity and mortality. Seronegative recipients are at high risk for developing toxoplasmosis and should be given prophylaxis and receive careful follow-up.

Correlation of parasite load determined by quantitative PCR to clinical outcome in a heart transplant patient with disseminated toxoplasmosis

Disseminated toxoplasmosis is a life-threatening infection in transplant recipients, which results either from reactivation of latent infection or from organ-transmitted primary infection. Preventive measures and diagnostic screening methods differ between countries and are related to the seroprevalence of Toxoplasma spp. in the general population. Here we report a case of disseminated toxoplasmosis in a heart transplant recipient with previous immunity that occurred after cotrimoxazole prophylaxis for the prevention of Pneumocystis jirovecii pneumonia was stopped. Quantitative PCR proved useful for the diagnosis and monitoring of Toxoplasma infection. Decreasing parasitic burdens in sequential samples of cerebrospinal fluid, blood, and bronchoalveolar lavage fluid correlated with a favorable outcome and allowed modulation of the immunosuppressive drug regimen. The duration of anti-Toxoplasma treatment and the need for maintenance prophylaxis are discussed, as well as prophylaxis for solid-organ transplant recipients. Although a rare event in heart transplant recipients, Toxoplasma reactivation must be investigated promptly, since early treatment improves the prognosis.

False serologic evidence for acute primary toxoplasmosis during liver transplantation for fulminant hepatitis B: a case report

Acute primary Toxoplasma gondii infection is usually considered to be a contraindication for solid organ transplantation. Recent reports of acute T. gondii infection have highlighted the need to include T. gondii serology in the pretransplant screening of solid-organ transplant recipients. However such serology might be misleading. We describe the case of a 25-year-old woman who received a liver transplantation for life-threatening liver failure due to hepatitis B virus infection. The presence of high IgM titers against T. gondii, as detected by membrane immunoassay, immunofluorescence, and mu-capture ELISA tests, together with the absence of IgG antibodies in the immediate pretransplant serology screening suggested acute primary T. gondii infection at the time of transplantation. We initiated a preemptive therapy with intravenous clindamycin and cotrimoxazole. However, negative PCR and IgA capture assays, together with the absence of a sustained IgG response finally excluded the initial diagnosis of primary toxoplasmosis, leading to discontinuation of antitoxoplasmosis therapy. This case illustrates the problem that, in the context of fulminant hepatitis B, serologic markers for acute primary toxoplasmosis can be falsely positive. Confirmation by PCR and IgA antibody determinations is required to confirm this diagnosis.

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.

Incidence and diagnosis of active toxoplasma infection among liver transplant recipients in Western Turkey

Toxoplasmosis is a serious and potentially life-threatening disease in liver transplant recipients while they are immunosuppressed. We report the clinical and laboratory findings related to active toxoplasma infection associated with 40 immunosuppressed liver transplant procedures that took place over a 12-month period at a major transplant unit in Izmir, Turkey. Twenty-seven (67.5%) of the 40 transplant recipients were found to be seropositive for toxoplasma infection and therefore at risk of reactivated infection. From the serological status of the donors, which was ascertained in 38 of 40 cases, we identified 3 (7.9%) of 38 transplants to be from a seropositive donor to a seronegative recipient. In 10 (26.3%) of 38 transplants, both the donor and recipient were seronegative, and this excluded toxoplasma as a risk. A comparison of real-time polymerase chain reaction (PCR) and nested PCR was undertaken in combination with a range of serological assays (the Sabin-Feldman dye test, enzyme immunoassay immunoglobulin M, and immunosorbent agglutination assay immunoglobulin M). Ethylene diamine tetraacetic acid blood samples from 3 of the 30 recipients at risk from toxoplasma were found positive by PCR, but only 1 of these was found positive in both assays. Among the 3 PCR-positive patients, immunoglobulin M and immunoglobulin G antibody levels increased in only 1 patient. Correlations between symptoms, laboratory findings, and clinical management (use of anti-toxoplasma therapy) are presented. Our findings suggest that toxoplasma presents a significant risk to our liver transplant population and that PCR is a helpful addition in identifying active infections and hence in informing clinical management decisions.

Donor-transmitted toxoplasmosis in liver transplant recipients: a case report and literature review

Transmission of toxoplasmosis via liver transplantation is extremely uncommon. Here we report the case of a 52-year-old male liver transplant recipient who on day 32 post transplant developed pneumonia followed by respiratory failure. Donor-transmitted toxoplasmosis was confirmed as the etiology by both serologic and molecular testing. We also review all previously published cases of toxoplasmosis in the English-language adult liver transplant literature.

Acute infection of Toxoplasma gondii and cytomegalovirus reactivation in a pediatric patient receiving liver transplant

A 7-year-old Mexican boy with end-stage cirrhosis underwent liver transplantation and was maintained with cyclosporine and prednisolone. No specific data about Toxoplasma gondii or cytomegalovirus (CMV) infections in the cadaver donor were available. The recipient was seronegative for Toxoplasma, but CMV-IgG positive before transplantation. Ganciclovir was administered for prophylaxis during 3 months, but 5 months later he presented with icterus and increased transaminases. Acute transplant rejection was ruled out by biopsy. A seroconversion for T. gondii IgM and IgG and a small increase in CMV-IgM antibodies were observed, although the CMV-polymerase chain reaction (PCR) was negative. Ganciclovir was re-started, and the patient improved, but 6 months later he relapsed, and chorioretinitis lesions compatible both with T. gondii and CMV infections appeared. Pyrimethamine, sulfadiazine, folinic acid, and ganciclovir were administered. The boy showed favorable clinical improvement and remained stable for 12 months. Then, new retinal CMV lesions appeared in both eyes and the PCR for CMV became positive; therefore, the patient received a new regimen of ganciclovir, and clinically improved. From these data we concluded that the child presented a reactivation of CMV and a primary infection with T. gondii after transplantation.

[Real-time PCR in the diagnosis of toxoplasmosis: the way to standardisation?]

Severity of toxoplasmosis is highly correlated to the immune status of the infected individual. Foetus and immunocompromised patient are mostly at risk to develop life threatening forms. In this situation, serological diagnosis gives poor information. DNA detection using polymerase-chain-reaction technology (PCR) has significantly improved the management of this disease. Even so, the growing number of conventional PCR assays has finally led to variable performance results. Real-Time PCR (RT-PCR) in toxoplasmosis has been developed since 2000. This new technology can improve standardisation. Moreover, quantification of parasitic load in samples becomes possible. This review describes the main RT-PCR procedures actually under use and the studies comparing different target genes. The effective benefit of quantification is also discussed. Reducing number of procedures and more systematic external quality control should be considered, in order to improve reliability in PCR results, which has undoubtedly become a major tool in toxoplasmosis diagnosis.

Comparison between two amplification sets for molecular diagnosis of toxoplasmosis by real-time PCR

PCR is now commonly applied to the diagnosis of toxoplasmosis. Although several methods are available, comparative studies are few, making it difficult to compare the performance of each technique. We compared the sensitivities of two real-time PCR assays through a prospective study on fetuses, neonates, and immunocompromised patients and on the ocular diagnosis of toxoplasmosis. The first system targeted the widely used B1 gene (GenBank accession number AF179871) while the second (RE) targeted a more recently described sequence repeated roughly 200 to 300 times (GenBank accession number AF146527). We demonstrated that molecular diagnosis requires the duplication of PCR assays, especially with the B1 system, as only one PCR was positive in 33.3% of cases. Our study showed that the RE target was more sensitive for all biological samples (amniotic fluid, placenta, aqueous humor, whole blood, and cerebrospinal and bronchoalveolar fluids) and significantly improved the performance of the diagnosis of toxoplasmosis. Taking into consideration all clinical samples, the mean gain in the crossing point value was 4.2 +/- 1.7 cycles and was even more significant for amniotic fluid (5.8 +/- 1.7 cycles).

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.

Comparative analysis of the VIDAS Toxo IgG IV assay in the detection of antibodies to Toxoplasma gondii

A new serological test, Vidas Toxo IgG IV, has been developed with antigens obtained from tachyzoites cultured on cells. Vidas Toxo IgG IV replaces Vidas Toxo IgG II by offering a more standardized antigenic production and a lower number of indeterminate results while retaining equivalent sensitivity and specificity.

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.

Evaluation of a Real-time PCR-based assay using the lightcycler system for detection of Toxoplasma gondii bradyzoite genes in blood specimens from patients with toxoplasmic retinochoroiditis

PCR based methods have advantages over traditional methods for the diagnosis of toxoplasmosis, especially when serology fails and clinical symptoms are not evident. However, current PCR-based assays are often labour-intensive and not readily quantifiable and have the potential for contamination due to a requirement for postamplification sample handling. Real-time PCR can address these limitations. We have developed and evaluated a highly sensitive Real-time PCR (Light-cycler, LC-PCR) to detect and quantify Toxoplasma gondii B1 and bradyzoite specific genes (SAG-4, MAG-1) in serum and peripheral blood mononuclear cells (PBMC) specimens, from five immunocompetent subjects with clinically suspected toxoplasmic retinochoroiditis (TRC) or without a suspected T. gondii infection. A standard curve for quantitation of parasitic load was generated using SYBR Green I fluorescent detection. The results were compared with those obtained with a nested PCR (n-PCR). In TRC patients, both PCR methods confirmed ophtalmoscopy and fluorangiographic findings. Among the TRC patients, the use of LC-PCR was more sensitive than n-PCR for detection and quantification of either B1 gene (P<0.001) or SAG-4/MAG-1 gene (P<0.05). LC-PCR has been shown particularly useful to accurately determine the parasite DNA load in follow-up specimens in whom the performance of either B1 or SAG-4 and MAG-1 in detecting T. gondii loads, varied with respect to specific antitoxoplasmic treatment.

Comparison of PCR-enzyme-linked immunosorbent assay and real-time PCR assay for diagnosis of an unusual case of cerebral toxoplasmosis in a stem cell transplant recipient

A PCR-enzyme-linked immunosorbent assay and a real-time PCR assay were compared for diagnosis and follow-up of cerebral toxoplasmosis in a stem cell transplant recipient. The sensitivity of detection was similar for both assays but was higher when the assays were performed on buffy coat rather than on whole blood or serum.