Serological and molecular screening of umbilical cord blood for Toxoplasma gondii infection; a reply to Botein et al

International audienc

Serologic Screening for Neospora caninum, France

International audienc

Treatment of toxoplasmosis: Current options and future perspectives

Toxoplasmosis is a worldwide parasitic disease infecting about one third of humans, with possible severe outcomes in neonates and immunocompromised patients. Despite continuous and successful efforts to improve diagnosis, therapeutic schemes have barely evolved since many years. This article aims at reviewing the main clinical trials and current treatment practices, and at addressing future perspectives in the light of ongoing researches

Comparison of three commercial multiplex PCR assays for the diagnosis of intestinal protozoa

Although microscopic examination of stool samples remains the reference method for the diagnosis of intestinal protozoal infections, these techniques are time-consuming and require operators who are experienced and well trained. Molecular biology seems to offer performances at least equivalent in terms of sensitivity and specificity for certain parasites. This study aimed to compare three multiplex PCR assays on 93 prospectively collected positive stools (prospective cohort) and a panel of 12 more Cryptosporidium-positive samples (Cryptosporidium panel). On the prospective cohort, the sensitivity was 89%, 64% and 41% for Giardia sp. detection for BD MaxTM, G-DiaParaTM and RIDA®GENE, respectively and 75%, 100% and 100% for C. parvum/hominis detection. The sensitivity of the RIDA®GENE assay for all Cryptosporidium species was 100%, and for D. fragilis 71%. All the techniques obtained the same results for E. histolytica detection, with one positive sample. All species in the Cryptosporidium panel were identified by the RIDA®GENE PCR. The BD MaxTM and G-DiaParaTM assays detected only C. parvum/hominis with the exception of one positive sample for C. meleagridis. No assay showed satisfactory results for all parasites simultaneously, and the DNA extraction seems to be the critical step. More studies are needed to standardize this procedure

Endogenous IL-33 Accelerates Metacestode Growth during Late-Stage Alveolar Echinococcosis.

During the course of the infectious disease alveolar echinococcosis (AE), the larval stage of Echinococcus multilocularis develops in the liver, where an initial Th1/Th17 immune response may allow its elimination in resistant individuals. In patients susceptible to infection and disease, the Th2 response initiates later, inducing tolerance to the parasite. The role of interleukin 33 (IL-33), an alarmin released during necrosis and known to drive a Th2 immune response, has not yet been described during AE. Wild-type (WT) and IL-33-/- C57BL/6J mice were infected by peritoneal inoculation with E. multilocularis metacestodes and euthanized 4 months later, and their immune response were analyzed. Immunofluorescence staining and IL-33 enzyme-linked immunosorbent assay (ELISA) were also performed on liver samples from human patients with AE. Overall, metacestode lesions were smaller in IL-33-/- mice than in WT mice. IL-33 was detected in periparasitic tissues, but not in mouse or human serum. In infected mice, endogenous IL-33 modified peritoneal macrophage polarization and cytokine profiles. Th2 cytokine concentrations were positively correlated with parasite mass in WT mice, but not in IL-33-/- mice. In human AE patients, IL-33 concentrations were higher in parasitic tissues than in distant liver parenchyma. The main sources of IL-33 were CD31+ endothelial cells of the neovasculature, present within lymphoid periparasitic infiltrates together with FOXP3+ Tregs. In the murine model, periparasitic IL-33 correlated with accelerated parasite growth putatively through the polarization of M2-like macrophages and release of immunosuppressive cytokines IL-10 and transforming growth factor β1 (TGF-β1). We concluded that IL-33 is a key alarmin in AE that contributes to the tolerogenic effect of systemic Th2 cytokines. IMPORTANCE Infection with the metacestode stage of Echinococcus multilocularis, known as alveolar echinococcosis, is the most severe cestodosis worldwide. However, less than 1% of exposed individuals, in which the immune system is unable to control the parasite, develop the disease. The factors responsible for this interindividual variability are not fully understood. In this in vivo study comparing wild-type and IL-33-/- infected mice, together with data from human clinical samples, we determined that IL-33, an alarmin released following tissue injury and involved in the pathogenesis of cancer and asthma, accelerates the progression of the disease by modulating the periparasitic microenvironment. This suggests that targeting IL-33 could be of interest for the management of patients with AE, and that IL-33 polymorphisms could be responsible for increased susceptibility to AE

Invariant NKT Cells Drive Hepatic Cytokinic Microenvironment Favoring Efficient Granuloma Formation and Early Control of Leishmania donovani Infection

The development of inflammatory granulomas around infected Kupffer cells is necessary for hepatic parasite clearance during visceral leishmaniasis. Invariant NKT (iNKT) cells are predominant T cells in the mouse liver and can synthesize large quantities of IL-4 and IFN-γ, two cytokines involved in granuloma formation. This study analyzed the role of iNKT cells in the hepatic immune response during Leishmania donovani infection, using a murine model of wild-type (WT) and iNKT cell-deficient (Jα18-/-) C57BL/6 mice sacrificed 15, 30 or 60 days post-infection. We recorded hepatic parasite loads, cytokine expression, and analyzed granulomatous response by immunohistochemistry and hepatic immune cell infiltration by flow cytometry. Whereas WT animals rapidly controlled the infection and developed an inflammatory response associated with a massive influx of iNKT cells observed by flow cytometry, Jα18-/- mice had significantly higher parasitic loads on all time points. This lack of control of parasite burden was associated with a delay in granuloma maturation (28.1% of large granulomas at day 60 versus 50.7% in WT). Cytokine transcriptome analysis showed that mRNA of 90/101 genes encoding chemokines, cytokines and their receptors, was underexpressed in Jα18-/- mice. Detection of IL-4 and TNF-α by ELISA in liver extracts was also significantly lower in Jα18-/- mice. Consistent with flow cytometry analysis, cytokinome profile in WT mice showed a bias of expression towards T cell-chemoattractant chemokines on D15, and displayed a switch towards expression of granulocytes and/or monocytes -chemoattractant chemokines on D60. In Jα18-/- mice, the significantly lower expression of CXCL5, MIP-2 and CCL2 mRNA was correlated with a defect in myeloperoxidase positive-cell attraction observed by immunohistochemistry and with a lower granulocyte and monocyte infiltration in the liver, as shown by flow cytometry. These data indicate that iNKT cells play a role in early and sustained pro-inflammatory cytokine response warranting efficient organization of hepatic granulomas and parasite clearance

Maternal Anti-Toxoplasma Treatment during Pregnancy Is Associated with Reduced Sensitivity of Diagnostic Tests for Congenital Infection in the Neonate

Neonatal diagnosis of congenital toxoplasmosis is based on a combination of serological and molecular tests. Maternal screening and treatment differ according to national policies and may impact the sensitivity of diagnostic methods in infants at birth. In this multicenter study, 115 neonates born to 61 treated (53%) and 54 (47%) untreated women were retrospectively included in three centers (France, Serbia, and the United States) to assess the impact of maternal anti-Toxoplasma treatment on the performance of neonatal workup at birth (neosynthesized anti-Toxoplasma IgM, IgA, and IgG and quantitative PCR [qPCR]) using univariate and multivariate approaches. Independently of the time of maternal seroconversion, the serological techniques were impacted differently by maternal treatment. The detection of IgM by immunosorbent agglutination assay (ISAGA) and Western blotting (WB) dropped from 90.7% and 88.2% in untreated neonates to 533% and 51.9% in treated neonates (P lt 0.05), whereas IgM enzyme-linked immunosorbent assay (ELISA) and IgA ISAGA were not significantly affected by maternal treatment. A 2-fold reduction in the sensitivity of neosynthesized IgG by WB was also observed in the case of treatment during pregnancy (37.7% versus 82.3%). Interestingly, the effect of treatment was shown to be duration dependent, especially for IgM detection, when the treatment course exceeded 8 weeks, whatever the therapy. The sensitivity of Toxoplasma PCR in blood was also lowered by maternal treatment from 39.1% to 23.2%. These results highlight that anti-Toxoplasma therapy during pregnancy may set back biological evidence of neonatal infection at birth and underline the need for a careful serological follow-up of infants with normal workup.This is the peer-reviewed version of the article: Guegan, H.; Štajner, T.; Bobić, B.; Press, C.; Olariu, R. T.; Olson, K.; Srbljanović, J.; Montoya, J. G.; Đurković-Đaković, O.; Robert-Gangneux, F. Maternal Anti-Toxoplasma Treatment during Pregnancy Is Associated with Reduced Sensitivity of Diagnostic Tests for Congenital Infection in the Neonate. Journal of Clinical Microbiology 2021, 59 (2). [https://doi.org/10.1128/JCM.01368-20

Incidence of Pneumocystis jiroveci Pneumonia among Groups at Risk in HIV-negative Patients

International audienceBackground - Pneumocystis jiroveci pneumonia in human immunodeficiency virus (HIV)-negative immunocompromised patients is associated with high mortality rates. Although trimethoprim-sulfamethoxazole provides a very effective prophylaxis, pneumocystosis still occurs and may even be emerging due to suboptimal characterization of patients most at risk, hence precluding targeted prophylaxis. Methods - We retrospectively analyzed all cases of documented pneumocystosis in HIV-negative patients admitted in our institution, a referral center in the area, from January 1990 to June 2010, and extracted data on their underlying condition(s). To estimate incidence rates within each condition, we estimated the number of patients followed-up in our area for each condition by measuring the number of patients admitted with the corresponding international classification diagnostic code, through the national hospital discharge database (Program of Medicalization of the Information System [PMSI]). Results - From 1990 to 2010, 293 cases of pneumocystosis were documented, of which 154 (52.6%) tested negative for HIV. The main underlying conditions were hematological malignancies (32.5%), solid tumors (18.2%), inflammatory diseases (14.9%), solid organ transplant (12.3%), and vasculitis (9.7%). Estimated incidence rates could be ranked in 3 categories: 1) high risk (incidence rates >45 cases per 100,000 patient-year): polyarteritis nodosa, granulomatosis with polyangiitis, polymyositis/dermatopolymyositis, acute leukemia, chronic lymphocytic leukemia, and non-Hodgkin lymphoma; 2) intermediate risk (25-45 cases per 100,000 patient-year): Waldenström macroglobulinemia, multiple myeloma, and central nervous system cancer; and 3) low risk (<25 cases per 100,000 patient-year): other solid tumors, inflammatory diseases, and Hodgkin lymphoma. Conclusions - These estimates may be used as a guide to better target pneumocystosis prophylaxis in the groups most at risk

Comparison of Leishmania typing results obtained from 16 European clinical laboratories in 2014.

Leishmaniasis is endemic in southern Europe, and in other European countries cases are diagnosed in travellers who have visited affected areas both within the continent and beyond. Prompt and accurate diagnosis poses a challenge in clinical practice in Europe. Different methods exist for identification of the infecting Leishmania species. Sixteen clinical laboratories in 10 European countries, plus Israel and Turkey, conducted a study to assess their genotyping performance. DNA from 21 promastigote cultures of 13 species was analysed blindly by the routinely used typing method. Five different molecular targets were used, which were analysed with PCR-based methods. Different levels of identification were achieved, and either the Leishmania subgenus, species complex, or actual species were reported. The overall error rate of strains placed in the wrong complex or species was 8.5%. Various reasons for incorrect typing were identified. The study shows there is considerable room for improvement and standardisation of Leishmania typing. The use of well validated standard operating procedures is recommended, covering testing, interpretation, and reporting guidelines. Application of the internal transcribed spacer 1 of the rDNA array should be restricted to Old World samples, while the heat-shock protein 70 gene and the mini-exon can be applied globally