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Diphtheria: antibodies to diphtheria toxin in the blood

Alexey Portnov, medical expert
Last reviewed: 23.04.2024

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The causative agent of diphtheria Corynebacterium diphtheriae, was isolated in its pure form by Loeffler in 1884. Corynebacterium diphtheriae is distinguished by polymorphism. In recent years, there has been a sharp increase in the incidence of diphtheria. Diagnosis of diphtheria is based on clinical and epidemiological data. To confirm the diagnosis, a bacteriological method of investigation is used, aimed at revealing the etiological factor - Loeffler's rods. The causative agent of diphtheria can be isolated after 8-12 hours in the event that the patient did not take antibacterial drugs. However, it should be borne in mind that when antibiotics (especially penicillin or erythromycin) are taken before taking a material for a bacteriological study, the growth of bacteria can not be obtained within 5 days (or there is no growth at all). In these cases, serological diagnostic methods are used.

Serological methods for the diagnosis of diphtheria use indirect hemagglutination and ELISA. Determine the antibody titre to the diphtheria toxin at the onset of the disease (day 1-3) and after 7-10 days, the antibody titre growth is considered to be diagnostic by no less than 4 times. RPGA is characterized by high sensitivity and specificity. In recent years, the RPHA method is replaced by the ELISA method, which has even greater sensitivity and specificity.

If a contingent is identified for vaccination, the antibody titer is determined before vaccination, if it is low or no antibodies, vaccination is indicated to the patients, its effectiveness is judged by the increase in antibody titer after vaccination. The main goal of active immunization is the development of specific immunity. Anatoxin serves as an insurmountable barrier to diphtheria toxin and protects the body from intoxication.

Determination of antibody titre to diphtheria toxin is necessary for the diagnosis of diphtheria infection, assessment of immunity in the examinees, evaluation of the effectiveness of vaccination with diphtheria vaccine.

Titers of antitoxic antibodies characterizing the degree of susceptibility to diphtheria

Titer AT, IU / ml	Interpreting the result
Less than 0.01	The subject is susceptible to diphtheria
0.01	The minimum level of circulating antibodies, providing some protection
0.01-0.09	Levels of circulating antibodies that provide some protection
0.1	Protective level of circulating antibodies
≥1.0	The level of antitoxin, providing a persistent long-term immunity to diphtheria

trusted-source [1], [2], [3], [4], [5], [6],

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