Tetanus is caused by Clostridium tetani bacteria entering the body through a wound. The bacteria produces a neurotoxin called tetanospasmin that causes painful muscle spasms and rigidity. Symptoms typically begin with lockjaw and stiffness of the neck muscles before becoming generalized. The disease is often fatal if untreated. Diagnosis is clinical based on symptoms, though the bacteria can sometimes be identified from wound samples. Treatment involves antitoxin administration to neutralize the toxin along with antibiotics. Prophylaxis through active immunization with tetanus toxoid vaccines or passive immunization with antitoxin is important to prevent occurrence.

1. Dr Mostafa Mahmoud, MD, Ph D,
Consultant Microbiologist
Associate Prof. of Microbiology & Immunology
Faculty of Medicine, Ain Shams University

2. Tetanus
 Tetanus is an acute, often fatal, disease caused
by an exotoxin produced by Clostridium tetani.
 It is characterized by generalized rigidity and
convulsive spasms of skeletal muscles.
 The muscle stiffness usually involves the jaw
(lockjaw) and neck and then becomes
generalized.
 Minimal inflammation and even unnoticed
wound in most of the cases.

3.  C. tetani is a slender, gram-positive, anaerobic
rod that may develop a terminal spore, giving it
a drumstick appearance.
 The vegetative organism is sensitive to heat and
cannot survive in the presence of oxygen.
 The spores, in contrast, are very resistant to
heat and the usual antiseptics surviving
autoclaving at 121°C for 10–15 minutes.
 The spores are also relatively resistant to phenol
and other chemical agents.
Clostridium tetani

4.  The spores are widely distributed in soil and in
the intestines and feces of horses, sheep, cattle,
dogs, cats, rats, guinea pigs, and chickens.
 Spores also present in human skin in
agriculture areas.

5. Cl. Tetani Toxins
 2 important toxins (tetanolysin and tetanospasmin
)are produced by vegetative organisms:-
 The function of tetanolysin is not known with
certainty.
 Tetanospasmin is a neurotoxin and causes the
clinical manifestations of tetanus.
 On the basis of weight, tetanospasmin is one of the
most potent toxins known. The human lethal dose
is 2.5 nanograms per kilogram of body (2.5 ng/Kg).

6. Modes of transmission:
 Contamination of wound with spores present
in soil or dust as in car accidents, in wars, and
puncture wounds e.g. gun shot.
 Postoperative tetanus occurs due to
imperfectly sterilized cat-gut.
 Contamination of uterine wound after labour
or abortion.
 Contamination of umbilical cord stump in the
newly born (tetanus neonatorum).

7. Pathogenesis:
 C. tetani usually enters body through a wound.
 In the presence of anaerobic conditions, the
spores germinate and produce toxins.
 Toxins disseminated via blood and lymphatics.
 Toxins act at CNS sites including peripheral
motor end plates, spinal cord, and brain, and in
the sympathetic nervous system.
 The toxin interferes with the release of inhibitor
neurotransmitters, Leading to muscle
contraction and spasm.

8. Clinical Picture
1. Incubation period ranges from 3 to 21 days,
(average 8 days) depending upon site from
CNS.
2. The shorter the incubation period, the higher
the chance of death.
3. In neonatal tetanus, symptoms usually appear
from 4 to 14 days after birth, (averaging 7
days).

9. Tetanus may be:
1- local: affecting the muscles at site of infection
(rare - less fatality).
2- Cephalic: following otitis media and affecting
the cranial nerves.
3- Generalized tetanus: the most common (80%)
start with trismus (locked jaw) then neck
stiffness, difficult swallowing, then abdominal
rigidity.
- There is also fever, sweating, hypertension.

10.  4- The neonatal tetanus: generalized form, in
non-immunized mother, via the umbilical cord
stump in developing countries.

11. Tetanus in its severest form

12. Tetanus neonatorum Child Tetanus

13. Complications:
1- Breathing difficulties.
2- Spinal and long bone fracture.
3-Nosocomial infections due to long
hospitalization.

14. Laboratory Diagnosis
 There are no laboratory findings characteristic
of tetanus.
 The diagnosis is entirely clinical and does not
depend upon bacteriologic confirmation.
 C. tetani is recovered from the wound in only
30% of cases and can be isolated from patients
who do not have tetanus.
 Laboratory identification of the organism
depends most importantly on the
demonstration of toxin production in mice.

15. 1- Sample:
Wound aspirated pus or discharge if found transported
to the lab immediately or in anaerobic transport
system.
2- Direct Gram stain: Gram-positive bacilli with
drumstick terminal spore may be seen.
3- Culture: On blood agar incubated anaerobically, or
on Robertson cooked meat medium (fluid anaerobic
medium), followed by subculture on blood agar
incubated anaerobically at 37 0C, for 48 h. The
organism produces -hemolytic colonies (due to
production of tetanolysin); identified by Gram’s
stained film, B.R and animal pathogenicity.

16. 4- Animal pathogencity (Toxin detection):
- When a mouse is injected I.M. with isolated
organism from culture, the animal will develop
spastic paralysis starting in the tail and site of
injection and spreading to all over the body
(ascending paralysis).
- Toxin demonstration in vivo is confirmatory.

17. Treatment:
 Antitoxin (Drug of choice) should be given at
once in order to neutralize toxin, human or
horse antitoxin may be given (human
antitoxin 3,000-10,000 unit I.V, or horse
antitoxin 100,000 unit 1/2 I.M and 1/2 I.V.).
 Penicillin or metronidazole.
 Removal of necrotic debris from wound.

18. Prophylaxis: (better than cure)
 Active immunization: Alum precipitated
tetanus toxoid; given in combination with
diphtheria toxoid and pertussis vaccine (DPT). 3
I.M. doses at 2, 4, and 6 months of age, booster
dose is recommended every 10 years.
- Booster dose to pregnant women can be given to
guard against neonatal tetanus.
 Passive immunization: tetanus antitoxin; to
wounded persons without previous history of
vaccination. 250-500 units of human serum or
1500-5000 units horse serum I.M. give protection
for 2-4 weeks.

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