Obstetric tetanus
Obstetric tetanus is a zoonthroponous bacterial acute infectious disease with a contact mechanism of transmission of the causative agent, which develops during pregnancy and is characterized by involvement of the nervous system, spasms of the skeletal muscles and the manifestation is possible of generalized seizures.
In Bulgaria, European countries and the USA, it is extremely rare in medical practice, due to the available, and in our country, free vaccines against tetanus, which are administered several times in childhood and adolescence and subsequently every 10 years.
What are the causes?
The causative agent of the disease is an obligate anaerobic gram-positive spore-forming bacterium Clostridium tetani belonging to the Bacillaceae family. The spores are located terminally, thus giving the infectious microorganisms the appearance of tennis rackets.
S. tetani form a highly active exotoxin /tetanospasmin/, a cytotoxin /tetanolysin/ and the so-called low molecular weight fraction.
Spores can be stored for years in soil, feces and on various objects.
They withstand a temperature of 90 degrees for 2 hours and more.
In anaerobic conditions, at a temperature of 37 degrees Celsius, sufficient humidity and in the presence of aerobic bacteria, for example staphylococci, the spores are transformed into vegetative forms.
They die after a few minutes when boiling, after 30 minutes – at 80 degrees Celsius. Antiseptics and disinfectants destroy the causative agent of the disease within 3-6 hours.
In countries with a warm climate, spore vegetation is possible directly in the soil.
Two types of antigens are identified in Clostridium tetanus – somatic /O-antigens/ and flagellar /H-antigens/. By structure, flagellar antigens are divided into 10 serotypes.
All serotypes form tetanospasmin and tetanolysin, which are identical in their antigenic properties.
• Tetanospasmin is one of the strongest biological poisons.
It is a polypeptide with a “distanced” mechanism of action, since bacteria rarely leave the confines of the initial focus of the infection, that is, the formed wound.
The toxin attaches to the surface of nerve cell axons, penetrates them due to ligand-mediated endocytosis and through retrograde axonal transport penetrates into the central nervous system.
Its mechanism of action is related to suppressing the release of neurotransmitters in synapses. Initially, the toxin acts on the peripheral nerves, causing local tetanic muscle contractions.
In a nutrient medium under laboratory conditions, the toxin appears on the 2nd day, reaching a peak in its formation on the 5th 7th day.
• Tetanolysin exhibits hemolytic, cardiotoxic and lethal effects, causes the development of local necrotic lesions. In the pathogenesis of obstetric tetanus, this toxin is of less essential importance.
The maximum accumulation of the toxin in a nutrient medium is observed after 20-30 hours.
The processes of its formation are not related to the synthesis of tetanospasmin.
The low molecular weight fraction enhances the secretion of neurotransmitters at neuromuscular synapses.
What are the symptoms?
In general, the occurrence of infectious diseases during pregnancy adversely affects both the mother and the fetus.
In most of the cases of obstetric tetanus described in the literature and registered, the pregnancy ends in premature birth or spontaneous abortion, in which abnormalities in the development of the fetus are found.
The clinical manifestations of this form of tetanus are almost identical to those when the disease develops outside the puerperium /postpartum period/, but a difference has been established consisting in a shorter incubation period – approximately 9-10 days, and the probability from the occurrence of death is higher – about 90%.
Treatment of obstetric tetanus
Isolation of the pregnant woman must be carried out, even in case of doubt.
The standard tetanus immunotherapy with human immunoglobulin is applied, but in the absence of access to such, an anti-toxic anti-tetanus heterologous serum is prescribed.
Vegetative forms of Clostridium tetanus are also destroyed by antibiotics of the penicillin class.
