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  • Author or Editor: Oliver Liesenfeld x
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Detection of IgG and IgM antibodies is commonly performed for the diagnosis of infection with Toxoplasma gondii. We determined the accuracy of the Elecsys Toxo IgG and IgM test at four European laboratories compared to local reference methods. Coefficients of variation for reproducibility ranged from 1.0 to 6.5% for IgG and from 0.8 to 3.2% for IgM. Seroconversion panels revealed high overall concordance with the reference tests. The Elecsys test detected IgG antibodies earlier than the Cobas Core IgG test in 19 of 47 panels; persisting IgM antibodies were observed in the VIDAS but not the Elecsys test in five of 47 panels. In 31.4% of latent stage sera with persistent IgM antibodies (positive LIASON IgM), the Elecsys IgM test gave negative results indicating increased “clinical” specificity. Sensitivity and specificity of the Elecsys IgG assay ranged from 99.45 to 100% and 87.50–99.80%, respectively, and 91.11–95.74 and 98.45–99.79% for the Elecsys IgM assay, respectively.

In conclusion, excellent reproducibility and accuracy make the Elecsys Toxo G and M tests highly suitable for the detection of anti-T. gondii IgG and IgM antibodies. The lower detection rates for persistent IgM in the Elecsys IgM test increase “clinical” specificity and decrease the need for follow-up testing.

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Experimental models of ocular infection with Toxoplasma gondii

Ocular toxoplasmosis is a vision-threatening disease and the major cause of posterior uveitis worldwide. In spite of the continuing global burden of ocular toxoplasmosis, many critical aspects of disease including the therapeutic approach to ocular toxoplasmosis are still under debate. To assist in addressing many aspects of the disease, numerous experimental models of ocular toxoplasmosis have been established. In this article, we present an overview on in vitro, ex vivo, and in vivo models of ocular toxoplasmosis available to date.

Experimental studies on ocular toxoplasmosis have recently focused on mice. However, the majority of murine models established so far are based on intraperitoneal and intraocular infection with Toxoplasma gondii. We therefore also present results obtained in an in vivo model using peroral infection of C57BL/6 and NMRI mice that reflects the natural route of infection and mimics the disease course in humans. While advances have been made in ex vivo model systems or larger animals to investigate specific aspects of ocular toxoplasmosis, laboratory mice continue to be the experimental model of choice for the investigation of ocular toxoplasmosis.

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Clostridium difficile infection is a significant health burden, and innovative solutions are needed to shorten time to diagnosis and improve infection control. We evaluated the performance of the cobas® Cdiff test for use on the cobas® Liat® System (cobas® Liat® Cdiff), a single-sample, on-demand, and automated molecular solution with a 20-min turnaround time. The limit of detection was 45–90 colony-forming units (CFUs)/swab for toxigenic strains that covered the most prevalent toxinotypes, including the hypervirulent epidemic 027/BI/NAP1 strain. Using 442 prospectively collected clinical stool specimens, we compared the performance of the cobas® Liat® Cdiff to direct culture and to the cobas® Cdiff test on the cobas® 4800 System (cobas® 4800 Cdiff) – a mediumthroughput molecular platform. The sensitivity and specificity of the cobas® Liat® Cdiff compared to direct culture were 93.1% and 95.1%, respectively, and this performance did not statistically differ from the cobas® 4800 Cdiff (P > 0.05). Direct correlation of the cobas® Liat® and cobas® 4800 Cdiff tests yielded overall percent agreement of 98.6%. The test performance, automation, and turnaround time of the cobas® Liat® Cdiff enable its use for on-demand and out-of-hours testing as a complement to existing batch testing solutions like the cobas® 4800 Cdiff.

Open access

We performed a cross-sectional study to determine the seroprevalence of Toxoplasma gondii infection in 308 domestic pigs slaughtered in La Paz, Baja California Sur State, Mexico using the modified agglutination test (MAT, cut off 1:25). Forty (13%) of the 308 pigs were seropositive with MAT titers of 1:25 in 16, 1:50 in 5, 1:100 in 4, 1:200 in 5, 1:400 in 3, 1:800 in 3, 1:1600 in 2, and 1:3200 in 2. Multivariate analysis of pigs’ characteristics showed that seropositivity to T. gondii was negatively associated with mixed breed (OR = 0.02; 95% CI: 0.003–0.26; P = 0.001). Other variables including sex, type of raising, and municipality did not show an association with T. gondii seropositivity by multivariate analysis. The frequency of high antibody titers (≥1:400) was significantly higher (P < 0.001) in Landrace pigs than mixed breed pigs. The seroprevalence of T. gondii infection in pigs for slaughter in Baja California Sur State is low compared with seroprevalences reported in pigs in other Mexican states. Landrace pigs demonstrated higher seroprevalence rates and antibody levels than mixed breed pigs. This is the first report of T. gondii infection in pigs raised in a desert climate.

Open access

Abstract

Peroral infection with Toxoplasma gondii results in a Th1-type immunopathology characterized by small intestinal necrosis and is dependent on IL-18. In the present study, we investigated whether treatment with IL-18 binding protein (IL-18bp) prevents ileal pathology. We observed increased expression of IL-18bp in intestinal biopsies of mice following infection. Whereas small intestines of control mice showed severe necrosis with complete destruction of the small intestinal architecture, mice treated with IL-18bp daily displayed only mild inflammatory changes including flattening of villi and edema in the space between the epithelium and lamina propria. Small intestinal parasite loads and concentrations of pro-inflammatory cytokines did not differ in control and IL-18bptreated mice. Binding of IL-18 to immobilized IL-18bp revealed a remarkably slow dissociation rate, indicating high affinity. Using chimeric mice we observed that bone marrow-derived rather than stromal cells were the primary source of IL-18 that resulted in small intestinal pathology following peroral infection with T. gondii. In conclusion, the results presented here suggest that IL-18bp may be an effective and safe treatment for small intestinal inflammation. Antigen-presenting rather than epithelial cells appear to be the main source of IL-18 in T. gondii-induced small intestinal inflammation.

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We compared the analytical and clinical performance of cobas® CT/NG for use on the cobas® 6800/8800 Systems with the cobas® 4800 CT/NG Test from urogenital and extragenital specimens in over 12,000 specimens from both male and female subjects in Germany and the United States. The analytical sensitivity was ≤40 EB/ml for Chlamydia trachomatis (CT) and ≤1 CFU/ml for Neisseria gonorrhoeae (NG). Using clinical specimens, the overall percent agreement with the cobas® 4800 CT/NG Test was >98.5%. Across urogenital specimens, there were 93 discrepant specimens; 76 (93.8%) of 81 CT discrepant specimens were 6800+/4800− and 10 (83.3%) of 12 NG discrepant specimens were 6800+/4800−. Sequencing verified CT results for 45 (61.6%) of 73 samples positive by 6800 and 1 (20%) of 5 positive by 4800. Similarly, 7 (70.0%) of 10 NG samples positive by 6800 and 1 of 2 positive by 4800 were confirmed by sequencing. Among discrepant extragenital specimens (all 6800+/4800−), 7 (50%) of 14 oropharyngeal and 23 (76.7%) of 30 anorectal CT discordant samples were confirmed as CT positive by sequencing; all 8 anorectal and 20 (90.9%) of 22 oropharyngeal NG discordant results were also confirmed as NG positive. In conclusion, cobas® CT/NG for use on the cobas® 6800/8800 Systems provides high-throughput automated solutions for sexually transmitted infection (STI) screening programs.

Open access

The presence of tissue cysts of Toxoplasma gondii has only poorly been investigated in autopsy series. We determined the presence of T. gondii cysts in a series of 51 autopsies in a public hospital using immunohistochemistry of brain and heart tissues. The association of tissue cysts with the general characteristics of the autopsy cases was also investigated.

Of the 51 cases studied, five (9.8%) were positive by immunohistochemistry for T. gondii cysts in the brain. None of the heart specimens was positive for T. gondii cysts. The presence of T. gondii cysts in brains did not vary with age, sex, birthplace, residence, education, occupation, or the presence of pathology in the brain. In contrast, multivariate analysis showed that the presence of T. gondii cysts was associated with undernourishment (OR = 33.90; 95% CI: 2.82–406.32; P = 0.005).

We demonstrated cerebral T. gondii cysts in an autopsy series in Durango City, Mexico. Results suggest that T. gondii can be more readily found in brain than in heart of infected individuals. This is the first report of an association between the presence of T. gondii in brains and undernourishment.

Open access

Little is known about the association of Toxoplasma gondii infection and neurological disorders. We performed a case-control study with 344 patients with neurological diseases and 344 neurologically healthy age- and gender-matched subjects. Sera of participants were analyzed for anti-T. gondii IgG and IgM antibodies using commercially available immunoassays. Anti-T. gondii IgG antibodies were detected in 25 (7.3%) cases and in 35 (10.2%) controls (odds ratio [OR] = 0.69; 95% confidence interval [CI]: 0.40–1.18; P = 0.17). Anti-T. gondii IgM antibodies were found in 5 (14.3%) of the 25 IgG seropositive cases and in 13 (37.1%) of the 35 IgG seropositive controls (P = 0.15). Anti-T. gondii IgG antibodies were found in 8 (3.8%) of 213 female cases and in 23 (10.8%) of 213 female controls (OR = 0.32; 95% CI: 0.14–0.73; P = 0.005); and in 17 (13.0%) of 131 male cases and in 12 (9.2%) of 131 male controls (P = 0.32). No direct association between IgG seropositivity and specific neurological disorders was detected. We found no support for a role of latent T. gondii infection in the risk for neurological disorders in this setting. With respect to specific neurological disorders, further studies using larger patient cohorts will be required.

Open access

The association of infection with Toxoplasma gondii and occupational exposure to animals has been scantly determined. We performed a case-control study with 200 subjects from Durango Province, Mexico, occupationally exposed to animals and 200 age- and gender-matched subjects without this occupation. Sera from all participants were analyzed for anti-T. gondii IgG and IgM antibodies using enzyme-linked immunoassays. The association of seroprevalence with sociodemographic, work, clinical, and behavioral characteristics in cases was determined.Cases and controls had similar frequencies of anti-T. gondii IgG antibodies (12/200: 6.0% and 11/200: 5.5%, respectively) (OR = 3.0; 95% CI: 0.12–73.64; P = 1.0). The frequency of sera with high (>150 IU/ml) levels of anti-T. gondii IgG antibodies was comparable among cases and controls (P = 0.61). Seroprevalence of anti-T. gondii IgM antibodies was similar in cases (4, 2.0%) than in controls (4, 2.0%) (P = 1.0). Multivariate analysis showed that seropositivity was associated with eating while working (OR = 7.14; 95% CI: 1.91–26.72; P = 0.003) and consumption of duck meat (OR = 5.43; 95% CI: 1.43–20.54; P = 0.01).No association between seropositivity to T. gondii and occupational exposure to animals was found. However, risk factors for infection found should be taken into account to reduce the exposure to T. gondii.

Open access

Through an age- and sex-matched case-control study, we sought to determine whether female sex workers have an increased risk of Toxoplasma gondii exposure and to determine the sociodemographic, work, clinical, and behavioral characteristics of these workers associated with T. gondii exposure. Female workers (n = 136) and controls (n = 272) were examined with enzyme-linked immunoassays (EIA) for the presence of anti-Toxoplasma IgG and IgM antibodies. IgM positive sera were additionally tested with enzyme linked-fluorescence immunoassay (ELFA). Anti-T. gondii IgG antibodies were found in 21 (15.44%) of 136 cases and in 10 (3.67%) of 272 controls (OR = 4.05; 95% CI: 1.84–8.89; P = 0.0001). Anti-T. gondii IgG levels higher than 150 IU/ml were found in 13 (9.6%) of 136 cases and in 8 (2.9%) of 272 controls (P = 0.007). Anti-T. gondii IgM antibodies were found in two cases and in six controls by EIA, but all were negative by ELFA. T. gondii seropositivity was associated with being born out of Durango State (OR = 10.47; 95% CI: 2.9–36.8; P < 0.01), injuries during sex work (OR = 6.30; 95% CI: 1.1–33.7; P = 0.03), and soil contact (OR = 4.11; 95% CI: 1.2–14.0; P = 0.02). This is the first report of an association of T. gondii infection and female sex workers.

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