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Joseph P, Calderón MM, Gilman RH, Quispe ML, Cok J, Ticona E, Chavez V, Jimenez JA, Chang MC, Lopez MJ, Evans CA. Optimization and evaluation of a PCR assay for detecting toxoplasmic encephalitis in patients with AIDS. J Clin Microbiol 2002; 40:4499-503. [PMID: 12454142 PMCID: PMC154600 DOI: 10.1128/jcm.40.12.4499-4503.2002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
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.
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Affiliation(s)
- Priya Joseph
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Maritza M. Calderón
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Robert H. Gilman
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
- Corresponding author. Mailing address: Asociacion Benéfica PRISMA (Proyectos en Informatica, Salud, Medicina y Agricultura), Carlos Gonzales 251 Urb, Maranga, San Miguel, Lima, Perú. Phone: 51 1 424 0221. Fax: 51 1 464 0781. E-mail:
| | - Monica L. Quispe
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Jaime Cok
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Eduardo Ticona
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Victor Chavez
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Juan A. Jimenez
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Maria C. Chang
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Martín J. Lopez
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
| | - Carlton A. Evans
- Northwestern University Medical School, Chicago, Illinois, Departments of Pathology & Microbiology, Universidad Peruana Cayetano Heredia, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura, Hospital Dos de Mayo, Department of Physiological Sciences and Tropical Medicine, Institute “Alexander Von Humboldt,” Universidad Peruana Cayetano Heredia, Lima, Peru, Wellcome Center for Clinical Tropical Medicine, Imperial College, London, United Kingdom
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Ashburn D, Davidson MM, Joss AW, Pennington TH, Ho-Yen DO. Improved diagnosis of reactivated toxoplasmosis. Mol Pathol 1998; 51:105-9. [PMID: 9713595 PMCID: PMC395619 DOI: 10.1136/mp.51.2.105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To identify antigens detected by western blotting in primary Toxoplasma gondii infection and determine their role in diagnosis of reactivated toxoplasmosis. METHODS Twenty three immunocompromised patients were tested by IgG western blotting. Patients were grouped retrospectively. Group 1 comprised 15 human immunodeficiency (HIV)/AIDS patients and included: group 1A (six patients with clinical and/or serological evidence of reactivation), group 1B (five patients with clinical evidence only), and group 1C (four asymptomatic patients). Group 2 comprised eight non-HIV/AIDS immunocompromised patients with clinical and/or serological evidence of reactivation. Immunocompetent patients (n = 23) with primary toxoplasmosis were a control group used to determine the progression of the antigens detected. RESULTS In primary toxoplasmosis, antibodies against 6, 20, 22, 23, 25, 28, 29, and 36 kDa antigens predominated. Detection of four or more of the 6, 20, 22, 23, 25, and 36 kDa antigens was considered to be western blot positive. In two group 1A patients, western blotting indicated past infection. During reactivation, this reverted to being western blot positive. Three other group 1A patients were western blot positive. In three of five group 1B patients, western blot positive results improved serological diagnosis of reactivated toxoplasmosis (p < 0.05). In two of five group 1B patients and all four group 1C patients, western blot indicated past infection. In group 2, two of eight patients reverted from a pattern of past infection to western blot positive. Five other patients from group 2 were western blot positive. CONCLUSIONS Detection of some low molecular weight antigens is diagnostic of reactivated toxoplasmosis. These antigens can be detected even with normal dye test titres and their detection improves the diagnosis of reactivated toxoplasmosis. They might be the result of the release of bradyzoites from ruptured tissue cysts.
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Affiliation(s)
- D Ashburn
- Scottish Toxoplasma Reference Laboratory, Microbiology Department, Raigmore Hospital NHS Trust, Inverness, UK
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