[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/) › Clostridium tetani

[Microbiology](https://durgical.com/en/microbiology/) · [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

# Clostridium tetani

- Bacterium
- Gram-positive
- Exam priority: high

A soil bacterium whose spores enter through wounds and make a toxin that causes severe muscle spasms; vaccination prevents it.

Updated 2026-11-01

Also called: tetanus bacillus

## Key points

- Tetanospasmin blocks GABA and glycine: spastic paralysis.
- Trismus, risus sardonicus and opisthotonos with a clear mind.
- Clinical diagnosis.
- Immune globulin + vaccine + debridement + metronidazole + benzodiazepines.
- The disease leaves no immunity: vaccinate afterwards.

## At a glance

**Gram**
Gram-positive

**Shape**
Rod with a terminal spore (drumstick)

**Oxygen**
Obligate anaerobe

**Family**
Clostridiaceae

**Stain**
Gram positive; spore former

## Morphology

- Slender Gram-positive rod
- Round terminal spore that gives a drumstick shape
- Spores resist heat and many antiseptics

## Transmission

- Spores from soil, dust, ash or animal faeces enter through wounds
- Deep, puncture or soil-contaminated wounds
- Umbilical cord cut with non-sterile tools (neonatal tetanus)
- Not spread from person to person

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- Tetanospasmin: travels up axons to the spinal cord
- Cleaves synaptobrevin and stops GABA and glycine release from inhibitory interneurons
- Result: sustained muscle contraction and spasms

## Diseases it causes

- Generalised, local, cephalic and neonatal tetanus [Tetanus →](https://durgical.com/en/conditions/tetanus/)

## Clinical picture

- Trismus (masseter spasm) as a frequent first sign
- Risus sardonicus and neck stiffness
- Opisthotonos and painful spasms set off by stimuli
- Autonomic instability; consciousness preserved

## Diagnosis

- The diagnosis is clinical
- Wound culture rarely helps and a negative culture does not rule it out

## Treatment

Human tetanus immune globulin to neutralise free toxin, wound cleaning and debridement, an antibiotic (metronidazole), and spasm control with benzodiazepines plus ventilatory support in intensive care. Having tetanus gives no immunity: the patient is vaccinated on recovery.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Metronidazole](https://durgical.com/en/pharmacology/metronidazole/)

## Prevention

- A complete tetanus toxoid series with boosters
- Proper wound care
- Tetanus immune globulin for high-risk wounds in people without a complete series
- Clean delivery and hygienic umbilical cord care

**Vaccine:** Tetanus toxoid is in Colombia's PAI: pentavalent vaccine in infants, a DTP booster at five years, Td in adults and Tdap in every pregnancy to protect the newborn.

## In Colombia

Neonatal tetanus (SIVIGILA event 770) and accidental tetanus are notifiable. Colombia maintains the neonatal tetanus elimination target (fewer than 1 case per 1 000 live births); every case is treated as a failure of the health system.

## Memory aid

Tetanus makes muscles tense: it cuts the brakes (GABA and glycine) and leaves the accelerator stuck.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the mechanism of tetanospasmin?

It cleaves synaptobrevin in spinal inhibitory interneurons and stops GABA and glycine release, so muscles stay contracted.

## What is usually the first sign of tetanus?

Trismus, a spasm of the jaw muscles.

## Why should a tetanus survivor be vaccinated?

Because the amount of toxin that causes disease is too small to induce protective immunity.

## How is neonatal tetanus prevented?

By vaccinating the pregnant woman with tetanus toxoid and with clean delivery and hygienic cord care.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/clostridium-tetani/)

## Related

- [Clostridium botulinum](https://durgical.com/en/microbiology/clostridium-botulinum/)
- [Corynebacterium diphtheriae](https://durgical.com/en/microbiology/corynebacterium-diphtheriae/)

## Related conditions

- [Tetanus](https://durgical.com/en/conditions/tetanus/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [About Tetanus](https://www.cdc.gov/tetanus/about/index.html) (CDC, 2024); [Tetanus](https://www.who.int/news-room/fact-sheets/detail/tetanus) (WHO, 2026); [Tetanus: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000615.htm) (MedlinePlus (NLM), 2024); [Informe de Evento 2023 Tétanos Neonatal](https://www.ins.gov.co/buscador-eventos/Informesdeevento/TETANOS%20NEONATAL%20INFORME%20DE%20EVENTO%20DE%202023.pdf) (Instituto Nacional de Salud (INS), Colombia, 2024).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/clostridium-tetani/