A 10-year retrospective comparison of two target sequences, REP-529 and B1, for Toxoplasma gondii detection by quantitative PCR.

This study aimed to evaluate the repeated sequence REP-529 compared to that of the B1 gene in the molecular diagnosis of toxoplasmosis by quantitative PCR (qPCR) in routine diagnosis. Over a 10-year period (2003 to 2013), all patients prospectively diagnosed with a positive REP-529 qPCR result for toxoplasmosis were included. All DNA samples (76 samples from 56 patients) were simultaneously tested using the two qPCR methods (REP-529 and B1). The mean cycle threshold (CT) obtained with the B1 qPCR was significantly higher (+4.71 cycles) than that obtained with REP-529 qPCR (P<0.0001). Thirty-one out of 69 extracts (45.6%) positive with REP-529 qPCR were not amplified with the B1 qPCR (relative sensitivity of 54.4% compared to that with REP-529), yielding false-negative results with 15/28 placenta, 5 cord blood, 2 amniotic fluid, 4 cerebrospinal fluid, 1 aqueous humor, 2 lymph node puncture, and 1 abortion product sample. This defect in sensitivity would have left 20/56 patients undiagnosed, distributed as follows: 12/40 congenital toxoplasmosis, 4/5 cerebral toxoplasmosis, 2/8 patients with retinochoroiditis, and 2 patients with chronic lymphadenopathy. This poor performance of B1 qPCR might be related to low parasite loads, since the mean Toxoplasma quantification in extracts with B1 false-negative results was 0.4 parasite/reaction. These results clearly show the superiority of the REP-529 sequence in the diagnosis of toxoplasmosis by PCR and suggest that this target should be adopted as part of the standardization of the PCR assay.

High level of soluble HLA-G in amniotic fluid is correlated with congenital transmission of Toxoplasma gondii.

The expression of human leukocyte antigen (HLA)-G on cytotrophoblast cells contributes to maternal-fetal tolerance. Soluble forms of HLA-G (sHLA-G) can be detected in amniotic fluid (AF) and a decrease of sHLA-G is known to be correlated to fetal loss. In this work we investigated the role of sHLA-G in the transplacental passage of the protozoan parasite Toxoplasma gondii, responsible for congenital toxoplasmosis in about 30% of fetuses when primary infection (PI) occurs during pregnancy. We determined the sHLA-G concentration in 61 AF from women with PI and 24 controls. Our results showed higher sHLA-G levels in AF from PI than in controls (p<0.001). Moreover sHLA-G level from congenitally infected fetuses (n=12) was higher than in fetus in whom congenital infection was ruled out (n=49, p<0.05). These data suggest that sHLA-G could participate in immunomodulation necessary to avoid fetal loss due to Toxoplasma infection, but that over-expression could favor congenital transmission.

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.

Bacterial and fungal counts in hospital air: comparative yields for 4 sieve impactor air samplers with 2 culture media.

We compared the yields of 4 recently developed sieve impactor air samplers that meet international standard ISO 14698-1, using 2 growth media (tryptic soy agar and malt extract agar) in real conditions of use. Several hospital sites expected to have different densities of airborne microflora were selected in 2 hospitals. The Samplair MK2, Air Ideal, and Mas-100 samplers yielded higher bacterial counts than did the SAS Super-100 device (P<.05). No significant differences in fungal counts were noted between the 4 devices. The use of malt extract agar in addition to tryptic soy agar significantly improved the fungal yield.

Tungiasis Outbreak in Travelers From Madagascar.

Seven patients from a group of 16 travelers were diagnosed at our institution with one or more sand fleas on their toes, 1 day to 3 weeks after returning from Madagascar. A questionnaire was sent to the whole group to collect clinical and epidemiological information, which showed that 9 of 13 (69%) had received pre-travel medical advice, but none were aware of sand flea; thus prevention measures were rarely applied. Five of seven (71%) patients wore open sandals throughout the trip. Overall, 10 sand fleas were extracted.

Incidence of Pneumocystis jiroveci pneumonia among groups at risk in HIV-negative patients.

BACKGROUND: 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.

The IL-33/ST2 axis is associated with human visceral leishmaniasis and suppresses Th1 responses in the livers of BALB/c mice infected with Leishmania donovani.

UNLABELLED: During visceral leishmaniasis, the control of hepatic parasite burden is mainly due to granuloma assembly in a microenvironment consisting of both Th1 and Th2 components. Using enzyme-linked immunosorbent assay (ELISA) dosages, quantitative PCR (qPCR), immunohistochemistry, and flow cytometry, we studied the role of interleukin-33 (IL-33), a recently described cytokine signaling through the ST2 receptor, during visceral leishmaniasis. We showed that a higher level of IL-33 was detected in the serum of patients with visceral leishmaniasis than in that from healthy donors and demonstrated the presence of IL-33(+) cells in a liver biopsy specimen from a patient. Similarly, in BALB/c mice experimentally infected with L. donovani, a higher level of IL-33 was detected in the serum, as well as the presence of IL-33(+) cells and ST2(+) cells in the mouse liver. In ST2(-/-) BALB/c mice, better control of the hepatic parasite burden and reduced hepatomegaly were observed. This was associated with strong induction of Th1 cytokines (gamma interferon [IFN-γ] and IL-12) compared to the level in wild-type (WT) mice and better recruitment of myeloid cells associated with strongly induced chemokines (CCL2 and CXCL2) and receptors (CCR2 and CXCR2). Conversely, BALB/c mice treated twice weekly with recombinant IL-33 showed a dramatically reduced induction of Th1 cytokines and delayed inhibition of monocyte and neutrophil recruitment in the liver, which was associated with reduced KC/CXCL1 and CXCR2 expression. Taken together, our results suggest that IL-33 could be a new deleterious regulator of the hepatic immune response against Leishmania donovani, via the repression of the Th1 response and myeloid cell recruitment. IMPORTANCE: Visceral leishmaniasis is a life-threatening systemic disease due to the Leishmania protozoa L. infantum and L. donovani and is ranked by the World Health Organization as the second most important protozoan parasitic disease after malaria for its grave morbidity, high mortality, and global distribution. Leishmania parasites subvert the host's immune response to propagate to target organs, including the spleen, the bone marrow, and the liver. Control of hepatic parasite burdens depends on a delicate and poorly understood Th1/Th2 immune balance. To better understand this complex immune response, new cytokines are interesting targets for research studies. IL-33 is a newly described cytokine usually associated with Th2 response and involved in different diseases, including infectious diseases and hepatitis. Our results suggest that IL-33 could be a new factor of susceptibility and a potential prognostic marker during visceral leishmaniasis.

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.

Immunostimulatory properties of dendritic cells after Leishmania donovani infection using an in vitro model of liver microenvironment.

BACKGROUND: Recent advances demonstrated that liver dendritic cells (DCs) promote immunologic hyporesponsiveness that may contribute to hepatic tolerance. Although there has been significant work on the phenotypic and functional roles of such DCs, the impact of liver microenvironment on the immune properties of infected DC is still poorly explored, probably because of the limitations of modelization. METHODOLOGY/PRINCIPAL FINDINGS: Here, we hypothesized that DC tolerogenic properties have an impact on the antimicrobial response, particularly during the infection by the protozoan parasite Leishmania donovani. Indeed, a lymphocytic Th2 environment was reported to favour the growth and proliferation of L. donovani. We first modelized an adequate monocyte-differentiated DC model, either in rat liver epithelial cell- or in a human hepatic non-parenchymal cell-conditioned medium in order to infect them further. We established that DCs differentiated in a hepatic microenvironment displayed a CD14+/CD16+/CD123+ phenotype, secreted low IL-12p70 and had an impaired capacity to stimulate allogeneic T lymphocyte proliferation and IFNgamma secretion. We then infected DCs with L. donovani in the in vitro-defined hepatic microenvironment. The infection of hepatic DCs restored their capacity to stimulate allogeneic T-cell proliferation and to induce lymphocytic secretion of IFNgamma. Such characteristics were recently shown to favour granuloma formation in mice liver. CONCLUSIONS/SIGNIFICANCE: Our results suggest that the specific immunostimulatory properties of infected hepatic DCs might amplify the granuloma maturation, which warrants the effective control of infection in the liver during visceral leishmaniasis.

Clinical relevance of placenta examination for the diagnosis of congenital toxoplasmosis.

BACKGROUND: Neonates with congenital toxoplasmosis, even asymptomatic at birth, should be treated early to reduce long-term sequelae. Postnatal diagnosis of congenital toxoplasmosis is essential because prenatal diagnosis fails to detect approximately 15% of cases or cannot be performed when maternal infection is acquired in late pregnancy. Detection of parasites in the placenta is one diagnostic approach to the early neonatal diagnosis of congenital toxoplasmosis. METHODS: The parasitic analyses of 102 placentas from cases of toxoplasmosis acquired during gestation were reviewed, with complete biologic follow-up of neonates. The value of quantitative PCR and mouse inoculation was assessed, and results are discussed in light of prenatal treatment and postnatal outcome. RESULTS: Congenital toxoplasmosis was diagnosed in 28 of the 102 cases. A prenatal diagnosis was obtained in only 16 cases. Specific IgM was detected in 57% of the babies at birth. A positive placental examination by PCR and mouse inoculation was the only evidence of infection in 3 neonates (11%) who were asymptomatic at birth. The sensitivities of PCR and mouse inoculation were 71% and 67%, respectively, and the specificities were 97% and 100%. Parasites were detected more often when maternal infection was acquired during the third trimester of pregnancy (P < 0.01), regardless the type of treatment. The sensitivity of IgM detection appeared to be related to maternal treatment since IgM was positive in 43% and 75% when mothers were treated or not, respectively (P < 0.01). Though 5/7 symptomatic infants had a positive placenta examination, there was no correlation between a positive placenta and the presence of clinical signs during the first year of life. The positive and negative predictive values of placental examination were 91% and 90%, respectively. CONCLUSION: Placental examination is an efficient tool for the early diagnosis of congenital toxoplasmosis.

Congenital toxoplasmosis after a preconceptional or periconceptional maternal infection.

We report a case of asymptomatic congenital toxoplasmosis following a periconceptional infection of the mother. Fetal infection is very uncommon in such a situation, and mostly associated with fetal damage. We recommend that newborns undergo postnatal screening, even after maternal periconceptional infection, and receive specific therapy to reduce long-term sequelae.

Comparison of the immunomodulatory effects of L. donovani and L. major excreted-secreted antigens, particulate and soluble extracts and viable parasites on human dendritic cells.

In an experimental model of human monocyte-derived dendritic cells (DCs), the immunophenotype of mature DCs infected with Leishmania donovani and Leishmania major showed a weak decrease in the cell surface expression of CD40, CD86, HLA-DR and DC-SIGN compared with uninfected control DCs. This immunomodulatory effect was more pronounced after stimulation with excreted-secreted antigens (ESA) of both species but absent after stimulation with particulate and soluble extracts. Infection with viable promastigotes, as well as stimulation with ESA from L. donovani and L. major, decreased IL-10 and IL-12p70 secretion. To our knowledge, this is the first direct demonstration that ESA from Leishmania promastigotes can stimulate DCs in the same manner as viable promastigotes.

In vitro and ex vivo permissivity of hepatocytes for Leishmania donovani.

Using models of ex vivo infection of murine, rat, and human primary hepatocytes by Leishmania donovani, we showed that hepatocytes are permissive for Leishmania at a low level. We then modeled the in vitro infection of a human hepatoma-derived cell line to examine the parasite's capability to proliferate and to cause direct damage to hepatocytes. Results showed that L. donovani can infect hepatocytes, but do not massively proliferate. This slight infection under our experimental conditions resulted in limited damage to hepatocytes. These results bring into question a possible role for hepatocytes as a parasite reservoir during latent infection.