Clostridium tetani is an anaerobic, spore-forming bacterium found in soil and the intestines of animals that produces a neurotoxin causing the serious disease tetanus. It enters the body through wounds and produces a potent toxin called tetanospasmin that causes painful muscle spasms by blocking inhibitory motor nerve signals in the central nervous system. Symptoms include lockjaw, arched back, and risus sardonicus. Treatment involves wound cleaning, antibiotics, tetanus antitoxin, and vaccination to stimulate protective antibodies against the toxin.

1. Clostridium tetani
teaching basics
Dr.T.V.Rao MD
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 1

2. Clostridia:
general characteristics
Genus Clostridium contains a large
number of gram-positive, spore-
forming species, several of which are
able to produce disease in humans.
Most species are obligate anaerobes,
some will grow under microaerophilic
conditions.
Natural habitat: soil and the intestinal
Tract
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 2

3. History
• Tetanus was well known to ancient
people, who recognized the
relationship between wounds and
fatal muscle spasms. In 1884, Arthur
Nicolaier isolated the strychnine-like
toxin of tetanus from free-living,
anaerobic soil bacteria.
• Rosenbach and Kitasato contributed
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 3

4. Clostridium tetani
• Clostridium tetani is a rod-
shaped, anaerobic bacterium of the
genus Clostridium.. C. tetani is found
as spores in soil or as parasites in the
gastrointestinal tract of animals. C.
tetani produces a potent biological
toxin, tetanospasmin, and is the causative
agent of tetanus
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 4

5. Clostridium tetani
• Clostridium tetani is
an anaerobic
pathogenic bacterium
that is primarily found
in soil and animal
intestinal tracts.
• Cotton, dust
• Plaster of Paris
• Catugut
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
5

6. Morphology
• Gram + bacilli
• 4-8 x 0.5 microns
• Drumstick
appearance
• Obligatory
anaerobe
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
6

7. Cultural characteristics'
• Grows on blood agar with advancing
edges
• In gelatin stab fir tree appearance
• In Robertson cooked meat medium
produces turbidity gas
• Meat is not digested turns black
• First α hemolysis followed by β
hemolysis08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 7

8. C. tetani: key characteristics
Large, spore-forming,
motile, obligate anaerobic
bacillus (see below).
Ferments: proteins or
amino acids.
Produces: acetic acid,
fatty acids, NH3, CO2, H2,
and a strong exotoxin.
Tetanospasmin, a
powerful neurotoxin
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
8

9. Resistance of the Clostridium tetani
.Survives boiling upto
3 hours
• They can not
survive autoclaving
at 249.8 °F (121 °C)
for 20 minutes.
• The spores are also
relatively resistant
to phenol and other
chemical agents.
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
9

10. Biochemical reactions
• Indole +
• MR and VP test
negative
• H2 S not produce
• Nitrites are not
reduced
• Gelatin liqification
occurs
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
10

11. Tetanus etiology
• In necrotic and infected
wounds, anaerobic conditions
will permit germination.
Contaminated puncture
wounds can be particularly
dangerous, especially when a
foreign body is present.08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 11

12. Mode of Transmission -
Tetanus
• Mode of Transmission: Transmission is
primarily by contaminated wounds,
Tissue injury( surgery, burns,deep
puncture wounds, crush wounds, Otitis
media ,dental infection, animal bites,
abortion, and pregnancy
• Incubation Period: 8 DAYS ( 3-21
DAYS)
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 12

13. Type of Tetanus
• Traumatic tetanus
• Puerperal tetanus
• Otogenic tetanus
• Idiopathic tetanus
• Tetanus
Neonatroum
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
13

14. Tetanus – Toxin oriented disease
• C. tetani usually enters a host through a
wound to the skin and then it replicates.
Once an infection is established, C.
tetani produces two
exotoxins, tetanolysin and tetanospasmin..
The genes that produce toxin are encoded
on a plasmid which is present in all
toxigenic strains, and all strains that are
capable of producing toxin produce
identical toxin
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 14

15. Nature of Toxins
• C. tetani produces two exotoxins,
tetanolysin and tetanospasmin.
The function of tetanolysin is not
known with certainty.
• Tetanospasmin is a neurotoxin and
causes the clinical manifestations of
tetanus.
• Tetanospasmin estimated Human lethal
dose 2.5 ng/kg
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 15

16. Toxins
• Hemolysin ( tetanolysin )
• Neurotoxin ( Tetanospasmin )
• Non spasmogenic toxin
• Tetanolysin is heat labile and oxygen laible
• Toxin is responsible for the Tetanus
• Heat laible inactivated at 650
c
• Mol wt Heavy chain 93,000
Light chain 52,000 bound by disulphide bonds
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 16

17. Tetanospasmin
• Mol wt Heavy chain 93,000
Light chain 52,000
bound by disulphide bonds
• Human – 130 nanograms
• Horse and guinea pigs guinea
pigs rabbits effected
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 17

18. Tetanospasmin
• Tetanospasmin is distributed in
the blood and lymphatic system of
the host. The toxin acts at several
sites within the central nervous
system, including peripheral
nerve terminals, the spinal cord,
and brain, and within
the sympathetic nervous system.08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 18

19. Tetanospasmin
• The toxin is taken up into within the
nerve axon and transported across
synaptic junctions, until it reaches the
central nervous system, where it is
rapidly fixed to gangliosides at the
presynaptic junctions of inhibitory
motor nerve ending
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 19

20. Pathogenicty
• The spores germinate
in reduced oxygen
potential devitalized
tissues, presence of
foreign bodies
• Motor neurons absorb
• Spread Intraaxonally
to CNS
• Avidly fixed to
gangliosides of gray
matter08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
20

21. Mechanism of Action
of Tetanus Toxin
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 21

22. Tetanospasmin
• Resembles strychnine blocks synaptic
inhibition in the spinal cord
• At inhibitory terminals that use glycine and
GABA as neurotransmitters
• Toxin acts presynaptically unlike
styrchnine post synaptically
• Muscle spasms of agonists and
antagonists
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 22

23. How Toxin acts
• The toxin, by blocking the release
of inhibitors, keeps the involved
muscles in a state of contraction
and leads to spastic paralysis , a
condition where opposing flexor
and extensor muscles
simultaneously contract. Death is
usually from respiratory failure.08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 23

24. Clinical manifestations
• The clinical manifestations of tetanus
are caused when tetanus toxin blocks
inhibitory impulses, by interfering with
the release of neurotransmitters,
including glycine and gamma-
aminobutyric acid. This leads to
unopposed muscle contraction and
spasm.
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 24

25. Tetanus
• Involves somatic musculkar system
• Injuries
• Punctured wound
• Surgery
• Otitis media
• Septic abortion
• Cow dung applications
• Ear boring circumcision
• Incubation 2 days to weeks
• Average 6 12 days
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 25

26. 08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
26

27. Opisthotonus
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
27

28. Photo Courtesy of U.S. Centers for Disease
Control and Prevention
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 28

29. Tetanus symptoms & signs
• Characteristic
features are risus
sardonicus (a
rigid
smile), trismus (comm
only known as "lock-
jaw"), and
opisthotonus
(rigid, arched back).
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 29

30. Risus Sardonicus in Tetanus Patient
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 30

31. Laboratory Diagnosis
of Tetanus
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 31

32. Laboratory Diagnosis
• Clinical diagnosis most important
in management
• Microscopy
• Culture
• Animal Inoculation
• Microscopy not reliable
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 32

33. Culture
• Done on Blood agar
• One half of plate spreads to other half after 1 – 2
days of incubation anerobically
• Three tubes of cooked meat broth inoculated
• 1 tube 800
c for 15 mt
• 2 tube 800
c for 5 mt
• 3 tube unheated
• All are incubated at 370
c upto 4 days
• Subcultured
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 33

34. Clostridium tetani Gram Stain
Round terminal spores give cells a “drumstick” or “tennis
racket” appearance.08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 34

35. Showing spores and Grwoth on
Blood Agar plate
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
35

36. Toxigenicty tests
• In a plate of Blood divided into 2 halves first half
incorporated with 1500 / ml of antitoxin
• Hemolysis without antitoxin
• Bacteria grown in Robertson cooked meat
medium inoculated into tail of a mice
• A 2nd
animal injected with tetanus antitoxin 1000
units an hour earlier the test
• Spasm of tail of un inoculated mice spread to
limb and other side and the animal dies
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 36

37. Tetanus bacteria grow in RCM
Medium
• Bacteria
grown in
Robertson
cooked meat
medium
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
37

38. Treatment
• Treatment involves debridement, the antibiotic
metronidazole* active immunization with
tetanus toxoid , and passive immunization with
tetanus immune globulin.
• Prevention is through active immunization with
tetanus toxoid**. The toxoid stimulates the body
to make neutralizing antibodies against the
binding component of the tetanus toxin. Once
the antibody binds to the toxin, the toxin can no
longer bind to the receptors on the host cell
membrane
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 38

39. Prevention
Tetanus carries a 35% mortality rate, making prevention very important!
The best course is childhood immunizations, with consistent booster doses,
and prompt cleaning of wounds with hydrogen peroxide.
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
39

40. Prophylaxis
• Surgical attention
• Antibiotics
• Immunization
• Antibiotics <4 hours
• Erythromycin 5000 mg Bid
• Pencillin
• Local treatment with bacitracin, and
neomycin
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 40

41. Passive Immunization
• Tetanus antitoxin 1,500 IU s/c IM
• Test dose to be given
• Human Anti tetanus globulin 250
units
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 41

42. Passive Immunization
• Antitoxin (tetanus immune globulin) should be
administered immediately. This will inactivate toxins in
the blood.
• Wounds should be debrided to remove dead tissue or
foreign bodies.
• Antibiotics should be given to inhibit growth of C. tetani.
• A tetanus toxoid booster immunization should be given
to patients who have not received one within the last 5
years.
• If spasms occur, antispasmodic drugs should be used
and respiration maintained by a breathing apparatus if
necessary.
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 42

43. • Tetanus toxoid was developed by Descombey in
1924,
• Tetanus toxoid immunizations were used
extensively in the armed services during World
War II.
• Although the rates of seroconversion are
about equal,the adsorbed toxoid is
preferred because the antitoxin response
reaches higher titers and is longer lasting
than that following the fluid toxoid.
TETANUS TOXOID
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 43

44. Tetanus toxoid
• Tetanus toxoid
consists of a
formaldehyde-treated
toxin.
• There are two types
of toxoid available —
adsorbed (aluminum
salt
precipitated)toxoid
and fluid toxoid
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
44

45. Active Immunization
• 1st
dose - 6th
week
• 2nd
dose - 10th
week
• 3rd
dose - 14th
week
• 1st
booster - 18th
month
• 2nd
booster - 6th
year
• 3rd
booster - 10th
year
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 45

46. Passive Immunization
1. ATS(equine) Ig- 1500 IU/s.c after
sensitivity test
(or)
2. ATS(human) Ig- 250-500 IU, no
anaphylactic shock, very safe and
costly.
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 46

47. Treatment of Tetanus patients
• Hospitalization
• Tracheotomy
• Human TIG 10,000 IU
• Pencillin, Metronidazole
• ATS IV
• Give active immunization.
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 47

48. 08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
48

49. PREVENTION OF NEONATAL
TETANUS
• 2 doses of T.T to all pregnant women
between 16 to 36 weeks of pregnancy with an
interval of 1 to 2 months between the two
doses.
• The first dose as early as possible & the
second dose a month later preferably 3
weeks before delivery.
• If the pregnant woman is previously
immunized, a booster dose is sufficient.
• If the pregnant woman is not immunized, then the
new born should be protected against tetanus by
giving tetanus human immunoglobulin 750 IU with in
6 hours of birth.08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 49

50. Triple Antigen vaccine
• Triple Antigen vaccine
is a combination of
Diphtheria, Tetanus,
and Pertussis. The
vaccine stimulates the
production of
antibodies to
immunize the body
against the causative
agents of the three
diseases listed above
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
50

51. Epidemiology
• Endospores are found in most soils and in the
intestinal tract of many animals and humans.
• Although exposure to endospores is common,
disease is uncommon except in countries with
poor medical care and vaccination compliance.
• It is estimated that there is more than one million
cases a year worldwide, with a mortality rate of
20% to 50%.
• Most deaths occur in neonates and originates
from infection of umbilical stumps in mothers
that have no immunity.
08/23/15 Dr.T.V.Rao MD @ Rao's Microbiology 51

52. Prevention is Better than
Cure
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
52

53. • Program Created and Designed by
Dr.T.V.Rao MD for the benefit of
Universal Education on Infectious
diseases
• Email
• doctortvrao@gmail.com
08/23/15 Dr.T.V.Rao MD @ Rao's
Microbiology
53