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Detection of diphtheria antitoxin by four different methods
V Skogen1, P A Jenum, V N Koroleva
1Department of Medicine, Institute of Clinical Medicine, University of Tromsø, Tromsø, NorwayDepartment of Bacteriology, National Institute of Public Health, Oslo, NorwayInstitute for Infectious Diseases of Children, Regional Hospital, Arkhangelsk, RussiaLaboratory of Epidemiologic Surveillance for Diphtheria, G. N. Gabrichevsky Institute for Epidemiology and Microbiology, Moscow, RussiaMedical Department B, University of Bergen, Haukeland Hospital, Bergen, Norway.
The in vivo neutralization test (NT) closely matched the in vitro NT for diphtheria antitoxin detection. Passive hemagglutination assay is suitable for individual vaccination decisions, but not for large-scale seroepidemiologic studies.
Area of Science:
- Immunology
- Infectious Disease Epidemiology
Background:
- Diphtheria antitoxin levels are crucial for assessing immunity and guiding vaccination strategies.
- Reliable detection methods are essential for both individual patient assessment and population-level seroepidemiologic studies.
Purpose of the Study:
- To evaluate the reliability of different diphtheria antitoxin detection methods used in Norway and Russia.
- To compare the performance of in vitro and in vivo neutralization tests, enzyme immunoassay (EIA), and passive hemagglutination assay (PHA).
Main Methods:
- 122 serum samples with a wide range of diphtheria antitoxin levels were analyzed.
- Methods included in vitro toxin neutralization (Vero cells), in vivo neutralization (rabbit skin), indirect EIA, and PHA.
- Results were categorized as not protected, relatively protected, or protected, with in vitro NT as the reference.
Main Results:
- The in vivo NT demonstrated high agreement with the in vitro NT (sensitivity 97%, specificity 87%, K=0.84).
- The indirect EIA showed high sensitivity (96%) but low specificity (30%) and poor agreement (K=0.29).
- The PHA test had high specificity (100%) but lower sensitivity (86%).
Conclusions:
- Neutralization tests (in vitro and in vivo) show high agreement for diphtheria antitoxin detection.
- PHA can guide individual vaccination decisions but is not recommended for seroepidemiologic studies due to low sensitivity.
- The indirect EIA method evaluated is not suitable for routine use.