Transcript Tetanus-chandana

TETANUS
By
Chandana Krishna
4th term
B.M.C
TETANUS
• Tetanus is a
medical condition
characterised by
prolonged
contraction of
skeletal muscle
fibres.
Introduction
• Primary symptoms by-tetanospasmin, a
neurotoxin produced by the Grampositive, obligate anaerobic bacterium
Clostridium tetani.
• Infection generally occurs through wound
contamination, & often involves a cut or
deep puncture wound.
Introduction
• As the infection progresses, muscle
spasms in the jaw develops, hence the
common name, lockjaw.
• This is followed by difficulty swallowing &
general muscle stiffness & spasms in
other parts of the body.
• Infection can be prevented by proper
immunisation & by post-exposure
prophylaxis.
Clostridium tetani
• Cl.tetani is widely
distributed in soil
& in intestine of
human beings &
animals.
• They cause
tetanus in both
man & animal.
Morphology
• Gram-positive, 48µm×0.5µm
bacillus.
• Has straight axis,
parallel sides &
rounded ends.
• Occurs singly &
occasionally in
chains.
Morphology
• It is capsulated & motile with peritrichate
flagella (except typeVI Cl. tetaninonflagellar strain).
• Young cultures are strongly Gram positive
but older cells show variable staining &
may be even Gram negative.
Cultural characteristics
• It is an obligatory anaerobe (grows only in
absence of oxygen).
• Optimum temparature-37°C & pH-7.4.
• It grows on ordinary media.
Cultural characteristics
• 1.Robertson’s cooked meat medium:
turbidity & some gas formation. The meat
is not digested but turns black on
prolonged incubation.
• 2.Blood agar: fine translucent film of
growth.α hemolysis is produced, which
later develops into β hemolysis, due to the
production of hemolysin (tetanolysin)
Cultural characteristics
• 3.Deep agar shake cultures: spherical
fluffy balls, 1-3mm in diameter, made of
filaments with radial arrangement.
• 4.Gelatin stab culture: fir tree appearance
with slow liquefaction.
Spore
• The spores are
spherical, terminal &
bulging, giving the
bacillus the
characteristic
‘drumstick’
appearance.
• Morphology
depends on stage of
development.
• Young spore may be
oval rather than
spherical.
Biochemical reactions
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Feeble proteolytic but no saccharolytic property.
Forms indole.
MR & VP negative.
H2S is not formed.
Nitrates are not reduced.
Gelatin liquefaction-slow.
Greenish fluorescence produced on media
containing neutral red.
Resistance
• Spore resistance to heat show strain
variation.
• Majority are killed by boiling for 15min.
• Some withstand boiling for 3hr & dry heat
at 160°C for 1hr.
• Spores can survive in soil for years & are
resistant to most antiseptics.
• Not destroyed by 5% phenol or 0.1% HgCl2
solution in 2 weeks or more.
Susceptibility
• Autoclaving at 121°C for 15min kills the
spores readily.
• Iodine(1% aqueous soon) and H2O2 (10
volume) kills spores within few hours.
Toxins
• All types produce same toxins which
are pharmacologically &
antigenically identical.
• Plasmid mediated.
• 1.Tetanolysin
• 2.Tetanospasmin
Tetanolysin
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Heat & O2 labile hemolysin.
Cause red cell lysis.
Pathogenic role not clear.
May act as leucocidin.
Tetanospasmin
• O2 stable & heat labile neurotoxin.
• Good antigen & specifically
neutralised by antitoxin.
• Similar to botulinum toxin in str.
• Gets toxoided spontaneously or in
presence of formaldehyde.
Pathogenesis
• Usual mode of infection-Penetrating
injury.
• Germination & toxin production
occurs only in favorable condition↓OR potential, devitalised tissues,
foreign bodies, concurrent infection.
• Resembles strychnine poisoning
Antigens
• All strains share common somatic (O)
antigen.
• On basis of flagellar (H) antigen 10 types(Ι
to X) are recognised by agglutination
tests.
• Type VI is non-flagellated strain.
1.Local tetanus
 Persistent spasm of
musculature at site of
primary infection (injury
site).
 Contractions persist for
weeks before subsiding.
 Its generally milder, 1%
cases are fatal but may
precede the generalised
tetanus.
2.Cephalic tetanus
• Primary site of infection is head injury or
otitis media.
• Associated with disfunction of 1 or more
cranial nerves, most commonly facial
nerve.
• Poor prognosis.
3.Generalised tetanus
• Most common form(80%
of cases).
• Presents with a
descending pattern.
• 1st sign is trismus(lockjaw)
-due to spasm of masseter
muscles.
• Followed by stiffness of
the neck, difficulty in
swallowing, rigidity of
abdominal muscles.
Risus sardoricus
• Characteristic
sardonic smile in
tetanus
• Results from
sustained contraction
of facial muscles.
Opthisthotonus
• Back spasm seen in
tetanus
4.Tetanus neonatorum
• It is the
generalised
tetanus that
occurs in newborn
infants.
• Occurs in infants
of non-immunised
mothers.
Tetanus neonatorum
• Occurs from infection
of un-healed umbilical
stump particularly
when stump is cut
with non-sterile
instrument.
• Very poor prognosis
Laboratory diagnosis
• Diagnosis made based on
clinical presentation.
• Specimen: Wound swab,
exudate or tissue from the
wound.
• 1.Direct smear & gram
staining
• 2.Culture
• 3.Animal inoculation
Direct smear
• Show Gram-positive
bacilli with drum-stick
appearance.
• Morphologically
indistinguishable from
similar nonpathogenic
bacilli.
Culture
• Done in blood agar & aminoglycoside
blood agar under anaerobic condition or
in Robertson’s cooked meat medium.
• Produces swarming growth after 1-2 days
of incubation.
• In contaminated specimen heat at 80°C for
10mins before culture to destroy nonsporing organisms.
Animal inoculation
• To demonstrate
toxigenicity.
• Positive case : test
animal develops stiffness
& spasm of tail &
inoculated hind limb
within 12-24hrs which
spreads to rest of the
body. Death occurs in 1-2
days.
Prophylaxis
• 1.Surgical attention
• 2.Antibiotics
• 3.Immunisation-passive,active or
combined.
Surgical Prophylaxis
 Aims at
 removal of foreign bodies,
necrotic tissue & blood
clots,
 To prevent an anaerobic
envt favourable for the
Clostridium tetanae
Antibiotic prophylaxis
• Aims at destroying or inhibiting tetanus
bacilli & pyogenic bacteria in wounds so
that toxin production is prevented.
• Long-acting Penicillin is the drug if
choice. Erythromycin is an alternative.
• Bacitracin or neomycin can be applied
locally.
• Has no action on toxin.
Immunisation
• Combined immunisation:
Tetanus
immunoglobulin(TIG) &
tetanus toxoid are given
on different arms.
• Provides both passive &
long-lasting immunity.
Treatment
• Isolate pt. from noise &
light which may provoke
convulsions.
• Followed by supportive
care.
• TIG is infused.
• Antibacterial therapy
started.
Epidemiology
• World wide
distribution- higher
in developing
countries due to
warm climate,
unhygienic practices
& poor medical
services.
Prevention & control
• By active immunisation
with tetanus toxoid.
1.TT-2 doses for pregnant
women,
2.DPT at 6, 10, 14 weeks
after birth,
3.DPT booster at 18 months
4.DT at 5yrs.
5.TT boosters at 10 & 16 yrs.
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