Dr. Alaa Al-Deen
Lec. 3
Tetanus
Mon
23 / 3 / 2015
2014 – 2015
ﻣﻜﺘﺐ ﺍﺷﻮﺭ ﻟﻼﺳﺘﻨﺴﺎﺥ
TETANUS Dr. Alaa Al-Deen
23-3-2015
1
TETANUS
MCQ
A 39-years-old lady is brought to ER with clinical diagnosis of tetanus after a
penetrating wound sole 15 days back. Regarding management of tetanus, what should
be line of action?
1. Inquire about her immunization status of tetanus.
2. Give tetanus toxoid irrespective of her immune status.
3. Give her TIG as a management protocol.
4. Reassure the relative as she does not need any immunization at present.
Causative agent
Clostridium tetani
Round terminal spores give
cells a “drumstick” or
“tennis racket” appearance
TETANUS Dr. Alaa Al-Deen
23-3-2015
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Morphology & Physiology
Relatively large, Gram-positive, rod-shaped bacteria.
Spore-forming, anaerobic.
Found in soil, and in the intestinal tracts and feces of various animals.
Reservoir
The organism is sensitive to heat and cannot survive in the presence of oxygen.
Spores are very resistant to :
- Heat
- radiation
- chemicals
- drying
Pores can survive for a long time in environment---100yrs possibly!
Virulence & Pathogenicity
Infection: by the production of a
potent protein toxin, tetanus
toxin or tetanospasmin.
TETANUS Dr. Alaa Al-Deen
23-3-2015
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Tetanus toxin
Is produced when spores germinate and vegetative cells grow after gaining access
to wounds. The organism multiplies locally and symptoms appear remote from
the infection site.
One of the three most poisonous substances known on a weight basis, the other
two being the toxins of botulism and diphtheria.
Because the toxin has a specific affinity for nervous tissue, it is referred to as a
neurotoxin.
when the oxygen levels of the surrounding tissue is sufficiently low, the
implanted C. tetani spore then germinates into a new, active vegetative cell that
grows and multiplies and most importantly produces tetanus toxin.
Tetanospasmin is an extremely lethal neurotoxin. It induces spastic paralysis (by
inhibiting release of inhibitory neurotransmitters).
Tetanospasmin at the wound site, the toxin starts to migrate along nerves
(peripheral motor nerve ending) where it blocks the release of inhibitory
neurotransmitters.
The anterior horn cell are affected after the exotoxin has passed into the blood
stream.
As a consequence of too much “activator transmitters”, muscles are OVER
stimulated to repeatedly contract—called spastic paralysis.
Mechanism of
Action of
Tetanus
Toxin
TETANUS Dr. Alaa Al-Deen
23-3-2015
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Symptoms
The first muscles affected by tetanus are that controlled by cranial nerves.
Facial and jaw muscle are first affected resulting in trismus, stiffness of jaw (also
called lockjaw).
Eye muscles (cranial nerves III, IV) rarely are involved.
If the muscle spasms affect the larynx or chest wall, they may cause asphyxiation.
Stiffness of abdominal, back muscles, extremities may become so violent and
strongly contracted, that bone fractures may occur.
As the disease progresses, other muscles become involved.
Generalized rigidity, spasms, opisthotonus.
Features of sympathetic over-activity are common (labile hypertension,
hyperpyrexia, arrhythmias (tachycardia), restlessness, agitation, sweating).
TETANUS Dr. Alaa Al-Deen
23-3-2015
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The affected individual is conscious throughout the illness, but cannot stop these
contractions (differentiated from seizures where the patient loses consciousness).
Persistent contraction of facial muscles (risus sardonicus or
rictus grin
) (like a
smile or grin).
Fever is usually absent.
Risus Sardonicus in Tetanus Patient
The back muscles are more
powerful, thus creating the arc
backward
“Oposthotonus” by Sir
Charles Bell, 1809.
Baby has neonatal tetanus with
complete rigidity
TETANUS Dr. Alaa Al-Deen
23-3-2015
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CEPHALIC TETANUS: A Rare Form of
Localized Tetanus
Courtesy : Google image on tetanus
A newborn showing risus sardonicus and
generalized spasticity
TETANUS Dr. Alaa Al-Deen
23-3-2015
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Most common types:
Generalized tetanus:
o Descending pattern: lockjaw stiffness of neck difficulty swallowing
rigidity of abdominal and back muscles.
o Spasms continue for 3-4 weeks, and recovery can last for months.
Neonatal tetanus:
o Form of generalized tetanus that occurs in newborn infants born without
protective passive immunity because the mother is not immune.
o Usually occurs through infection of the unhealed umbilical stump, particularly
when the stump is cut with an unsterile instrument.
Uncommon types:
Local tetanus:
persistent muscle contractions in the same anatomic area as the
injury, which will however subside after many weeks; very rarely fatal; milder
than generalized tetanus, although it could precede it.
Cephalic tetanus:
rare, occurs with ear infections or following injuries of the
head; facial muscles contractions.
Incubation period: 3-21 days, average 8 days.
In general, the farther the injury site
is from the central nervous system, the longer the incubation period. The shorter
the incubation period, the more severe the symptoms. In neonatal tetanus,
symptoms usually appear from 4 to 14 days after birth, averaging about 7 days.
Death may occur from tetanus, often from cardiac (heart) and respiratory (lung)
effects or secondary complications from the infection.
TETANUS Dr. Alaa Al-Deen
23-3-2015
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Diagnosis
The diagnosis of tetanus is based on clinical findings.
Although a characteristic electromyogram is suggestive.
Diagnostic studies generally are of little value, as cultures of the wound site are
negative for C. tetani two-thirds of the time.
- When the culture is positive, it confirms the diagnosis of tetanus.
Diagnosis unlikely to be tetanus:
Serum tetanus antitoxin once it is detected this is protective, and make
diagnosis of Tetanus unlikely.
Patient’s history of complete vaccination and appropriate booster make diagnosis
unlikely.
Treatment
If treatment is not sought early, the disease is often fatal.
Despite antibiotic had unproven value; however, it can eradicate the vegetative
cell.
Penicillin 10-12 million units I.V.
Metronidazole (500 mg 4X daily) to eradicate vegetative organisms in the
wound and prevent further toxin production.
The toxin is neutralized with shots of tetanus immunoglobulin (TIG) which binds
unbounded toxin.
Due to the extreme potency of the toxin, immunity does not result after the
active tetanus.
TETANUS Dr. Alaa Al-Deen
23-3-2015
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What else can be done?
Remove and destroy the source of the toxin through surgical exploration, and
cleaning of the wound (debridement).
Bed rest with a non-stimulating environment (dim light, reduced noise, and stable
temperature) may be recommended.
Sedation may be necessary to keep the affected person calm, relax the muscles,
and relieve pain.
Respiratory support with oxygen, endotracheal tube, and mechanical ventilation
may be necessary.
Method of prevention - immunization
A person recovering from tetanus should begin active immunization with tetanus
toxoid (Td) during convalescence.
The tetanus toxoid is a formalin-inactivated toxin, with an efficiency of approx.
100%.
Because the antitoxin levels decrease over time, booster immunization shots are
needed every 10 years.
… The end...