Toxoplasma serology, parasitemia and antigenemia in patients at risk for toxoplasmic encephalitis

Impact of Stereotactic Biopsy in HIV Patients

OBJECTIVE

During their disease a significant number of human immunodeficiency virus (HIV)-infected patients develop neurologic symptoms due to intracerebral pathologies. Entities commonly found are toxoplasmosis, lymphomas, or progressive multifocal leukoencephalopathy. In some patients, diagnosis is not feasible with imaging alone, requiring biopsy. The objective of this study was to evaluate the impact of stereotactic biopsy in HIV patients on adjustment of therapy.

METHODS

Between January 2004 and May 2015 at our clinic, 26 HIV-infected patients underwent stereotactic biopsy. Thin-layer magnetic resonance images were obtained and fused with computed tomography scans, taken with the stereotactic frame (Leksell) mounted. Biopsy material was evaluated pathologically and microbiologically.

RESULTS

Histologic analysis revealed B-cell lymphoma in 6 patients (23.1%) and progressive multifocal leukoencephalopathy in 2 patients (7.7%). Abscess and toxoplasmosis were found in 3 patients each (11.5% and 11.5%), and encephalitis occurred in 4 patients (15.4%). In 2 patients each (7.7%), vasculitis, metastasis, and glioblastoma were diagnosed. Further findings comprised non-Hodgkin lymphoma and Burkitt lymphoma in 1 patient each. After biopsy, treatment was significantly changed in 18 (69.2%) patients (P < 0.01). Antibiotic therapy was adjusted in 6 patients (23.1%), and chemotherapy in 3 patients (16.7%). Other changes included antibiotic/antiviral therapy to chemotherapy in 3 patients (16.7%), chemotherapy to radiation, cortisone to chemotherapy, and aciclovir to cortisone in 1 patient each. One patient with glioblastoma underwent resection, and another patient received radiation. One patient underwent palliative care.

CONCLUSION

Stereotactic biopsy in HIV-infected patients results in significant changes of therapy in more than two thirds of the patients.

Seroprevalence of cytomegalovirus, Toxoplasma gondii, syphilis, and hepatitis B and C virus infections in a regional population seropositive for HIV infection

OBJECTIVE

To determine the prevalence of exposure to cytomegalovirus (CMV), Toxoplasma gondii, syphilis, hepatitis B virus (HBV) and hepatitis C virus (HCV) in a large, well characterized, regional population presenting for human immunodeficency virus (HIV) care.

DESIGN

Demographic and serological data compiled prospectively in a relational database used for routine patient care. Results were analyzed for statistically significant trends within demographic subpopulations known to be at risk of such infections.

PATIENTS AND SETTING

A total of 1274 persons with documented HIV infection in southern Alberta have sought medical care since 1985. Serological status to CMV, T gondii, syphilis, HBV and HCV infections were routinely requested as part of the initial assessment. All patients with serological results available were included in the analysis.

RESULTS

CMV infection was found in 84.1% of patients. A lower prevalence of CMV infection in those under 30 yeasr old (P<0.001), intravenous drug users (IVDUs) (P=0.001) and in patients with transfusion-acquired HIV (P<0.001) was seen. T gondii seropositivity was found in 10.6% of patients, with an increased risk of seropositivity in those born outside of Canada (P<0.001). Syphilis seropositivity was present in 5.1% of patients, with a higher prevalence in gay males (P=0.1). HBV carrier status was noted in 8.0% of patients, with males having an increased risk (P=0.025). Since 1990, there has been a 17.6% prevalence of HCV, predominantly in IVDUs (P<0.001).

CONCLUSION

Seroprevalence to common pathogens in HIV disease varies significantly among subpopulations, necessitating individual testing.

Cardiac involvement with parasitic infections

Parasitic infections previously seen only in developing tropical settings can be currently diagnosed worldwide due to travel and population migration. Some parasites may directly or indirectly affect various anatomical structures of the heart, with infections manifested as myocarditis, pericarditis, pancarditis, or pulmonary hypertension. Thus, it has become quite relevant for clinicians in developed settings to consider parasitic infections in the differential diagnosis of myocardial and pericardial disease anywhere around the globe. Chagas' disease is by far the most important parasitic infection of the heart and one that it is currently considered a global parasitic infection due to the growing migration of populations from areas where these infections are highly endemic to settings where they are not endemic. Current advances in the treatment of African trypanosomiasis offer hope to prevent not only the neurological complications but also the frequently identified cardiac manifestations of this life-threatening parasitic infection. The lack of effective vaccines, optimal chemoprophylaxis, or evidence-based pharmacological therapies to control many of the parasitic diseases of the heart, in particular Chagas' disease, makes this disease one of the most important public health challenges of our time.

Antibody response of HIV-infected patients to latent, cerebral and recently acquired toxoplasmosis

The aim of this longitudinal study with 626 HIV-infected patients was to evaluate the capability of serological tests in diagnosing the presence of Toxoplasma gondii infection in HIV-infected patients, as well as the potential impact of various treatment regimes on serological results. Low IgG antibody levels and stable or declining titres predominated. IgM positivity occurred in ten patients (one seroconversion, seven latent, two cerebral toxoplasmosis). Complement fixation test (CFT) titres >or=1:32 imply that the relative risk of cerebral toxoplasmosis is 6.84 (95% confidence interval [CI] 1.44-32.5) but with a predictive value of only 14.0% (95% CI 5.3-27.9). Values of specific antibodies are not biassed by antiretroviral treatment and/or prophylaxis for toxoplasmosis, and the detection of specific antibodies is very useful in the identification of T. gondii infection in the HIV-infected population, but the role of serology in predicting the clinical manifestation of T. gondii infection is limited.

Synthesis, anti-Toxoplasma gondii and antimicrobial activities of benzaldehyde 4-phenyl-3-thiosemicarbazones and 2-[(phenylmethylene)hydrazono]-4-oxo-3-phenyl-5-thiazolidineacetic acids

In the present communication, a new series of 2-[(phenylmethylene)hydrazono]-4-oxo-3-phenyl-5-thiazolidineacetic acids (2a-p) have been synthesized. Benzaldehyde 4-phenyl-3-thiosemicarbazones substituted (1a-p) were also obtained and used as intermediate to give the title compounds. All synthesized compounds were characterized by IR, (1)H and (13)C NMR. The in vitro anti-Toxoplasma gondii activity of 1a-p and 2a-p was evaluated. The 4-thiazolidinones (2a-p) were screened for their in vitro antimicrobial activity. For anti-Toxoplasma gondii activity, in general, all compounds promoted decreases in the percentage of infected cells leading to parasite elimination. These effects on intracellular parasites also caused a decrease in the mean number of tachyzoites. In addition, most of the 4-thiazolidinones showed more effective toxicity against intracellular parasites, with IC(50) values ranging from 0.05 to 1 mM. According to results of antimicrobial activity, compounds 2f, 2l, and 2p showed best activity against Mycobacterium luteus, 2c was more active against Mycobacterium tuberculosis, and 2g, 2l, and 2n showed same activity as nistatin (standard drug) against Candida sp. (4249).

Inhibitory effect of aureobasidin A on Toxoplasma gondii

The apicomplexan parasite Toxoplasma gondii is a leading opportunistic pathogen associated with AIDS and congenital birth defects. Due to the need for identifying new parasite-specific treatments, the possibility of targeting sphingolipid biosynthesis in the parasite was investigated. Aureobasidin A, an inhibitor of the enzyme synthesizing the sphingolipid inositol phosphorylceramide, which is present in fungi, plants, and some protozoa but absent in mammalian cells, was found to block in vitro T. gondii replication without affecting host cell metabolism. Aureobasidin A treatment did not induce tachyzoite to bradyzoite stage conversion in T. gondii but resulted in a loss of intracellular structures and vacuolization within the parasite. In addition, aureobasidin A inhibited sphingolipid synthesis in T. gondii. Sphingolipid biosynthetic pathways may therefore be considered targets for the development of anti-T. gondii agents.

Optimization and evaluation of a PCR assay for detecting toxoplasmic encephalitis in patients with AIDS

Toxoplasma gondii is a common life-threatening opportunistic infection. We used experimental murine T. gondii infection to optimize the PCR for diagnostic use, define its sensitivity, and characterize the time course and tissue distribution of experimental toxoplasmosis. PCR conditions were adjusted until the assay reliably detected quantities of DNA derived from less than a single parasite. Forty-two mice were inoculated intraperitoneally with T. gondii tachyzoites and sacrificed from 6 to 72 h later. Examination of tissues with PCR and histology revealed progression of infection from blood to lung, heart, liver, and brain, with PCR consistently detecting parasites earlier than microscopy and with no false-positive results. We then evaluated the diagnostic value of this PCR assay in human patients. We studied cerebrospinal fluid and serum samples from 12 patients with AIDS and confirmed toxoplasmic encephalitis (defined as positive mouse inoculation and/or all of the Centers for Disease Control clinical diagnostic criteria), 12 human immunodeficiency virus-infected patients with suspected cerebral toxoplasmosis who had neither CDC diagnostic criteria nor positive mouse inoculation, 26 human immunodeficiency virus-infected patients with other opportunistic infections and no signs of cerebral toxoplasmosis, and 18 immunocompetent patients with neurocysticercosis. Eleven of the 12 patients with confirmed toxoplasmosis had positive PCR results in either blood or cerebrospinal fluid samples (6 of 9 blood samples and 8 of 12 cerebrospinal fluid samples). All samples from control patients were negative. This study demonstrates the high sensitivity, specificity, and clinical utility of PCR in the diagnosis of toxoplasmic encephalitis in a resource-poor setting.

Some aspects of protozoan infections in immunocompromised patients- a review

Protozoa are among the most important pathogens that can cause infections in immunocompromised hosts. These microorganisms particularly infect individuals with impaired cellular immunity, such as those with hematological neoplasias, renal or heart transplant patients, patients using high doses of corticosteroids, and patients with acquired immunodeficiency syndrome. The protozoa that most frequently cause disease in immunocompromised patients are Toxoplasma gondii, Trypanosoma cruzi, different Leishmania species, and Cryptosporidium parvum; the first two species cause severe acute meningoencephalitis and acute myocarditis, Leishmania sp. causes mucocutaneous or visceral disease, and Cryptosporidium can lead to chronic diarrhea with hepatobiliary involvement. Various serological, parasitological, histological and molecular methods for the diagnosis of these infections are currently available and early institution of specific therapy for each of these organisms is a basic measure to reduce the morbidity and mortality associated with these infections.

Molecular diagnosis of toxoplasmosis

Toxoplasmosis is an anthropozoonotic disease endemic world-wide, caused by the apicomplexan Toxoplasma gondii. Although the course of infection is generally benign, it can cause significant morbidity and mortality in the developing fetus and in immunocompromised individuals. Biological diagnosis classically relies upon serology and direct detection of the parasite by inoculation to laboratory animals. In the past decade, the use of the polymerase chain reaction (PCR) has made a significant improvement in both the prenatal diagnosis of congenital toxoplasmosis and the detection of acute disease in the immunocompromised patient. Nevertheless, like many 'in-house' PCR assays, the PCR-Toxoplasma suffers from lack of standardization and variable performance according to the laboratory. A wide variety of primers has been used in different assays, but few comparative tests have been performed. Moreover, in contrast to other parasitic diseases, PCR-Toxoplasma has not yet attained a sufficient level of sensitivity, regardless of the clinical condition considered. These drawbacks are discussed, together with the undoubted gain that PCR has brought to this difficult diagnosis.

Cardiac infections in the immunosuppressed patient

This article presents the various manifestations of cardiac infections found in the immunosuppressed host. Emphasis is placed on the correlation between specific impairments of host defenses and the occurrence of certain types of pathogens. The effect of immunosuppression on the clinical manifestations of these infections is discussed. Finally, appropriate diagnostic modalities are presented for the major types of infections.

TORCH testing in HIV-infected women

The issue of TORCH testing in pregnant women infected with the HIV virus remains confusing, even more so than it is in the non-HIV-infected gravida. Unfortunately, the data presented in this article make the recommendations of how to test for these various infections in pregnancy that much more difficult. Patients who are newly diagnosed as being HIV-infected and referred for prenatal care or who have not had TORCH testing probably should be tested. Thus, the prenatal patient with newly diagnosed HIV infection should be tested for T. gondii IgG antibodies. If positive for IgG antibodies, IgM antibodies should be obtained in an attempt to rule out acute T. gondii infection. Patients who test negative do not require any further testing until after the pregnancy unless they are severely immunocompromised and show signs and symptoms of toxoplasmosis. Antibodies (IgG) to CMV should be obtained in the HIV-infected gravida who is at high risk for CMV disease, i.e., patients with CD4+ T cell counts less than 100/mm3. Unfortunately, the previously described problems with antibody detection make this testing less than ideal; thus, it is not routinely recommended in the HIV-infected pregnant patient who presents for prenatal care except for those at risk of disease reactivation. As for herpes simplex virus testing, there is no value in routinely testing patients prenatally for evidence of the disease. Finally, syphilis testing in the HIV-infected gravida is of major importance. Once tested, the patient who tests negative and who remains at risk for infection should probably be retested in the third trimester. Patients who are found to have the disease and who are treated need to be tested serially to rule out re-infection or treatment failure.

Detection of Toxoplasma gondii by PCR and tissue culture in cerebrospinal fluid and blood of human immunodeficiency virus-seropositive patients

To investigate whether both tissue culture and PCR on a sequence from the repetitive rDNA could contribute to the diagnosis of toxoplasmosis, blood samples and, if they were available, cerebrospinal fluid (CSF) and aqueous humor samples from 72 human immunodeficiency virus-seropositive patients with suspected toxoplasmosis were prospectively tested. For 10 patients with fever of unknown origin but without confirmed toxoplasmosis, no Toxoplasma gondii was detected. For two patients with confirmed toxoplasmic uveitis, only PCR of aqueous humor samples was positive. Of 60 patients (48 with CSF samples) with neurological signs, 25 (from 13 of whom CSF samples were available) had confirmed cerebral toxoplasmosis and 10 had a positive PCR of CSF and/or blood samples, while for 1 patient culture of the CSF sample was also positive. Unlike tissue culture, PCR of rDNA is of value for the detection of cerebral toxoplasmosis in human immunodeficiency virus-seropositive patients, provided that both CSF and blood samples are available (sensitivity, 76.9%; specificity, 100%).

Diagnosis of Toxoplasma gondii infection in AIDS patients by a tissue-culture technique

Toxoplasma gondii infection was investigated in 14 AIDS patients with neurological involvement who showed clinical and computer tomographic scan signs suggestive of toxoplasmic encephalitis or extraneuronal localization suggestive of toxoplasmic infection. Blood, lung secretion (bronchoalveolar lavage and/or induced sputum sample) and cerebral spinal fluid (CSF) samples were cultured, and the results compared with the results of direct examination by Giemsa and by immunofluorescence of lung secretions and CSF. Toxoplasma gondii were observed directly in only four patients by immunofluorescence in bronchoalveolar lavage, induced sputum and CSF samples, and in three of these patients by Giemsa staining of bronchoalveolar lavage and CSF smears. In contrast, parasites were detected after 48 h in blood cultures from 11 of the 14 AIDS patients, in CSF cultures from eight of them and also in cultures of bronchoalveolar lavage and induced sputum from the six patients with respiratory and radiological features indicative of lung tissue damage. The findings indicate the value of tissue culture for diagnosis of toxoplasmosis as well as for monitoring the effects of treatment and also indicate that culture of induced sputum could be a powerful tool in establishing the incidence of pulmonary toxoplasmosis in AIDS patients.

Value of PCR for evaluating occurrence of parasitemia in immunocompromised patients with cerebral and extracerebral toxoplasmosis

PCR was used to evaluate the occurrence of Toxoplasma gondii parasitemia by detection of the B1 gene in blood samples in two groups of immunosuppressed patients (148 subjects) suspected of having cerebral or extracerebral infection, respectively. Group I consisted of 52 patients with AIDS with suspected cerebral toxoplasmosis. The diagnosis was clinically proven in 15 cases. Parasitemia was detected by PCR in only two of these patients (13.3%), both showing evidence of disseminated infection. Group II consisted of 96 immunocompromised patients, either with AIDS or receiving iatrogenic immunosuppressive therapy. Of these patients, 65 (34 with AIDS and 31 others) showed abnormalities only in chest radiography and were first screened for the presence of Toxoplasma DNA in bronchoalveolar lavage fluid. Blood was then analyzed when the parasite was detected in the bronchoalveolar lavage fluid. The remaining 31 subjects (22 with AIDS and 9 others) were suspected of having extracerebral, pulmonary, or disseminated toxoplasmosis, and blood was studied directly in these cases. Among the nine patients with clinically diagnosed extracerebral infection in group II, the parasite was detected by PCR in the blood of five patients (55.5%), all having pulmonary toxoplasmosis. If all patients with clinical manifestations of extracerebral toxoplasmosis (from both groups) who had not received antitoxoplasma therapy when the samples were collected are considered, PCR detected parasitemia in seven of the nine cases (77.8%). The present study indicates that examination of blood by PCR may be valuable in cases of extracerebral toxoplasmosis because of the disseminated nature of the disease. Since most cases of cerebral toxoplasmosis result from the local reactivation of latent brain cysts, detection of parasitemia by PCR is useful only in cases associated with severe cerebral infection or dissemination of this disease.

Use of murine subinoculation for the diagnosis and isolation of toxoplasmosis in HIV-infected patients with persistent lymphadenopathy

A murine model was used to try to elucidate the importance of Toxoplasma gondii infection in HIV-positive patients. Laboratory mice were inoculated with lymph node homogenates or buffy coats from 30 HIV-infected individuals with persistent lymphadenopathy. Sabin and Feldman dye-tests, direct agglutination tests and indirect immunofluorescence assays (IFA) of serum samples taken from the mice six weeks after inoculation indicated, respectively, that 26.6%, 43.4% and 33.3% of the lymph node inocula and 13.3%, 30.0% and 16.7% of the buffy coat samples had been Toxoplasma-positive. Histological examination of the brains of the infected mice revealed Toxoplasma tachyzoites or bradyzoites in the mice given buffy coat samples from one patient (3.3%) and those given lymph node material from three patients (10%). No protozoa were found in the brains of the control mice, all of which were sero-negative. In contrast to the mouse results, other, concurrent tests failed to detect any signs of toxoplasmosis infection in the patients, except relatively low titres of anti-Toxoplasma antibodies in 11 patients, even though two patients developed brain toxoplasmosis, one 12 and the other 18 months after the study. It appears, therefore, that an animal model can be very useful in the diagnosis of toxoplasmosis in HIV patients.