GRAM POSITIVE RODS. PART 3 Flashcards
CLOSTRIDIUM SPPECIES
Mention the four medically important species
- Clostridium tetan
- Clostridium botulinum
- Clostridium perfringes (cause gas gangrene or food poisoning)
- Clostridium difficile
common characteristics among all the 4 species of clostridium
All clostridia are anaerobic, spore-forming, gram-positive rods
where does clostridium naturally resides
They naturally inhabit the soil and the intestinal tracts of humans and
animals.
What does Clostridium tetani cause
causes tetanus.
Where are the spores of Clostridium tetani commonly found?
widespread in soil
What is the usual portal of entry for Clostridium tetani?
The usual portal of entry is a wound site, such as where a nail penetrates the foot.
What conditions favor the germination of Clostridium tetani spores in wounds?
by necrotic tissue and poor blood supply in the wound.
What type of tetanus is a major problem in some developing countries?
Neonatal tetanus, where the organism enters through a contaminated umbilicus or circumcision wound, is a major problem in some developing countries.
Explain the pathogenesis of clostridium tetanus
Tetanus toxin (tetanospasmin) is an exotoxin produced by vegetative cells
at thewound site.
* This polypeptide toxin is carried intra-axonally (retrograde) to the central
nervous system, where it binds to ganglioside receptors and blocks
releaseof inhibitory mediators (e.g., glycine and γ-aminobutyric acid
[GABA]) at spinal synapses.
* Symptoms usually appear approximately 7 days after the injury, but the
incubation period has been reported to range from 3 to 21 days.
* The length of incubation is related to the distance from the injury to the
central nervous system
symptoms of tetanus
Muscle Spasms: The disease causes painful muscle contractions, particularly in the jaw and neck muscles.
Generalized Tetanus: The most common type, where spasms begin in the jaw and progress throughout the body.
Incubation Period: Signs and symptoms appear within an average of 10 days after infection.
Severe Complications: Tetanus can be life-threatening, and there is no cure for it.
explain 5 clinical findings of clostridium tetanus
- Muscular rigidity, usually in the jaw known as lockjaw (trismus) which prevents
the mouth from opening: rigidity of the neck, and lumbar region. - Difficulty in swallowing results from muscular spasms in the pharyngeal area.
- Rigidity of the abdomen, chest, and limbs may also occur.
- Opisthotonos, a pronounced arching of the back due to spasm of the strong
extensor muscles of the back, is often seen (Refer to the picture on slide 22) - Respiratory failure ensues.
- A high mortality rate is associated with this disease
Laboratory diagnosis of clostridium tetanus
Laboratory diagnosis of tetanus infection is made on the basis of clinical
presentation
* Organisms are rarely isolated from the wound site.
* C. tetani produces a terminal spore (i.e., a spore at the end of
the rod).
* When Isolated on blood agar( occasionally), C. tetani produces a fine film
of feathery growth. Use a hand lens to examine the plate
* C. tetani is indole positive. It can be identified presumptively by the blood agar antitoxin test
Treatment for clostridium species
1.Tetanus immune globulin (tetanus antitoxin) is used to neutralize the
toxin.
2. The role of antibiotics is uncertain, if used, either metronidazole or
penicillin G can be given
3. An adequate airway must be maintained and respiratory support
given.
4. Benzodiazepines (e.g., diazepam [Valium]) should be given to prevent spasms
prevention of tetanus
- Immunization with tetanus toxoid (formaldehyde-treated
toxin) in childhood and every 10 years thereafter. - Tetanus toxoid is usually given to children in combination with
diphtheria toxoid and the acellular pertussis vaccine (DTaP)
