Clostridium tetani

http://textbookofbacteriology.net/clostridia_3.html

History1884- Arthur Nicolaier isolated the

bacteriumAntonio Carle & Giorgio Rattone

showed transmissibility by injecting human pus into rabbit sciatic nerve

1897- Edmund Nocard found the antitoxin could prevent and treat tetanus

P. Descombey developed the tetanus toxoid vaccine in 1924

CasesAround the early1800s- 200

cases per 100,000 peopleBy1947- 0.4 cases per 100,000

peopleDecrease because of wound care

improvements & vaccine

CharacteristicsGram +Rod shapedEndosporeVegetative cells

killed from O2 exposure

Spores survive in long periods of O2

Drum stick shape

May stain gram – or gram variable in older cells

Leaky peptidoglycan layer, layer too thin or too thick

11 known strainsDiffer in production

of toxin & flagellar antigens

HabitatLive in all anaerobic habitats

including soil, feces & intestinal tracts of various animals

Especially found in heavily manured soils

Virulence Factors: ToxinTetanospasmin, diphtheria & botulism

toxin top 3 most poisonous to humansSpores introduced through wound A-B Toxin is produced by spores during

cell stages: growth, sporulation & lysisMoves through path from local site to

CNSReleased through natural cell lysisToxin is synthesized as a150kDa

polypeptide chain

Virulence Factors Cont… ToxinChain cleaved by a protease into

a 100kDa heavy chain (fragment B) & a 50kDa light chain (A)

Connected by a disulfide bridgeB fragments bind to gangliosideA fragments have toxic

enzymatic activityNo useful function for C. tetaniHeat & O2 labile

Path of TetanospasminBinds to peripheral

nerve terminals Transported within

the axon Cross synaptic

junctions until it reaches the CNS

Rapidly fixed to gangliosides at the presynaptic inhibitory motor nerve endings

Taken up into the axon by endocytosis

Toxin blocks the release of inhibitory neurotransmitters by cleavage of synaptobrevin II (protein)

Required to inhibit nervous impulses

Continuous contractions are produced

http://www.clarian.org/ADAM/doc/NeurologyCenter/2/8679.htm

CNS

http://www.nature.com/nrn/journal/v4/n12/fig_tab/nrn1253_F1.html

TetanusLethal dose of

tetanospasmin is insufficient to provoke an immune response

Lab tests aren’t used

Physical exam for stiffness, pain & muscle spasms

Leads to death in 1:10 cases

The time between the injury and symptoms is less than 2 weeks

SymptomsSevere,

painful spasms

Rigidity of voluntary muscles

Difficulty swallowing

Death follows due to inability to breathe

1809: Sir Charles Bell's portrait of a soldier dying of tetanus.

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TreatmentAntimicrobial drugs eradicate the

bacterium Ex. PenicillinSevere cases used sedation &

mechanical ventilationRecovery can be several months

usually in the ICU so vital functions can be monitored

PreventionTetanus toxoid is

inactivated tetanus toxin

4 vaccines for diphtheria, pertussis & tetanus

DTaP, Tdap, DT, & Td

DTaP & DT are given to children under 7

Tdap & Td are given to 7 yrs & older

DT is given instead of DTaP if the pertussis isn’t tolerated well

Td is the booster shot given & Tdap is the same with pertussis as well

Children should get 5 doses

Adults should get a booster every 10 yrs or if exposed

RecommendationPregnant womenPeople that work

in the dirt or manure

Get lots of cuts and scrapes

Travelers to foreign countries with hot, damp climates

Children who haven’t received the vaccine

Adults older than 50

People that are not sure if they have received boosters

ConclusionVaccine has been safe since the

1920sEveryone should get the vaccine

and regular booster shotsTetanus is deadly although

treatable Prevention is the best tool

Sourceshttp://www.cdc.gov/vaccines/vpd-

vac/tetanus/default.htmhttp://www.healthscout.com/

ency/68/291/main.htmlhttp://

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