Transcript Clostridial diseases

Clostridial diseases
Anthrax
Clostridial diseases
 Clostridium
Gram
spp.
positive rods
Obligate anaerobes
Endospore forming
Clostridium spp.
Endospores
Resistant
to:
Heat
Disinfectants
Clostridium spp.
 Soil
(found on just about all
environmental surfaces)
 Fecal matter of humans and animals
 Aquatic sediments
Clostridium spp. (obligate
anaerobes)
 Rapidly
killed by highly reactive
oxygen radicals
Singlet
oxygen
Superoxide free radicals
The Clostridia genus
The clostridia produce a wide variety of
extracellular enzymes to degrade large
biological molecules in the environment into
fermentable components
 Hence, the clostridia play an important role in
nature in biodegradation and the carbon cycle
 In anaerobic clostridial infections, these
enzymes play a role in invasion and pathology

Grown in the laboratory
under anaerobic conditions
Who are the Clostridia’s?
Most of the clostridia are saprophytes but
a few are pathogenic for humans
 Those that are pathogens have primarily
a saprophytic existence in nature and, in a
sense, are opportunistic pathogens
 Clostridium tetani and Clostridium
botulinum produce the most potent
biological toxins known to affect humans

Clostridium perfringens

C. perfringens produces a huge array of invasins and
exotoxins, causes wound and surgical infections
that lead to gas gangrene, in addition to severe
uterine infections.
 Clostridial hemolysins and extracellular enzymes such
as proteases, lipases, collagenase and hyaluronidase,
contribute to the invasive process
 C. perfringens also produces an enterotoxin and is an
important cause of food poisoning.
 Usually C. perfringens and C. botulinum is
encountered in improperly sterilized (canned) foods in
which endospores have germinated
Clostridium difficile
Pseudomembranous colitis in humans is
caused by overgrowth ofClostridium difficile in
the colon, usually after the normal flora has
been disturbed by antimicrobial chemotherapy.
 C. difficile produces two toxins: Toxin A is
referred to as an enterotoxin because it causes
fluid accumulation in the bowel
 Toxin B is an extremely lethal (cytopathic)
toxin.

Clostridium tetani

Clostridium tetani is the causative agent of tetanus.
The organism is found in soil, especially heavilymanured soils, and in the intestinal tracts and feces
of various animals.
 Carrier rates in humans vary from 0 to 25%, and the
organism is thought to be a transient member of the
flora whose presence depends upon ingestion.
 The organism produces terminal spores within a
swollen sporangium giving it a distinctive drumstick
appearance.
 Although the bacterium has a typical Gram-positive
cell wall, it may stain Gram-negative or Gramvariable, especially in older cells.

Neutralization of oxygen radicals
 Superoxide
Dismutase (SOD)
 Catalase
 Clostridium
enzymes
spp. lacks these
Clostridium spp.
C. tetani
 C. botulinum
 C. perfringens
 C. difficile

Clostridium tetani
“Drumstick” appearance
Clostridial diseases
 Tetanus
 Botulism
 Gas
gangrene
 Foodborne gastroenteritis
 Pseudomembrane colitis
TETANUS
 Localized
infection, caused by
a C.tetani toxin
 General muscle spasms-due to
neurotoxin
TETANUS (cont.)
 Trauma
(often trivial)
 Chronic skin ulcers
 Umbilical cord (clay matter
ritual in Africa)
 Abortion (unsanitary
abortions)
TETANUS (cont.)
300,000/year world wide
100 cases/year in the USA (24
fatal)
70% unvaccinated, or
incomplete vaccination regime
Mostly 60 years and older
TETANUS (cont.)
Spores
in wound
Infection and/or tissue
necrosis
Low O2 tension
Spore germination
TETANOSPASMIN
Blocks
the muscle
relaxation pathway
Death results from spasms
of respiratory muscles
Released from dead
bacterial cells
TETANOSPASMIN (cont.)
Once
it attaches to nerves,
therapy is usually ineffective
Advanced case of tetanus
Greek tetanos, to stretch
TREATMENT OF TETANUS
Removal
of necrotized
(death) tissue
Antibiotics
Human immunoglobulins
TETANUS VACCINE
Toxin
Toxoid
Enzyme
-S-SActive
Inactive
TETANUS VACCINATION
SCHEDULE (CDC)
DTaP
vaccine (Diptheria,
Tetanus & acellular
pertussis)
2, 4, 6 and 12-18 months
4-6 years
FOODBORNE BOTULISM
A
non-infectious food
poisoning
C. botulinum neurotoxin
in contaminated food
34 cases in 1994 (USA)
FOODBORNE BOTULISM (cont.)
BOTULIN TOXIN
Most potent of all natural toxins
 Approx. 0.001 mg human
lethal dose
Causes flaccid paralysis
Death follows cardiac failure
Definitive Diagnosis
only establish with toxin identification:
 Isolation of toxigenic cultures and
identification of the involved type C or D
toxin with the aid of serum neutralization
in mice or guinea-pigs.
 Toxin detection in clinical samples
collected for laboratory analysis (intestinal
contents)

Type of tests to ID botulism
tests may include a brain scan, spinal fluid
examination, nerve conduction test
(electromyography, or EMG),
 The most direct way to confirm the diagnosis is to
demonstrate the botulinum toxin in the patient's
serum or stool by injecting serum or stool into mice
and looking for signs of botulism
 The bacteria can also be isolated from the stool of
persons with foodborne and infant botulism
 These tests can be performed at some state health
department laboratories and at CDC

BOTULIN TOXIN (cont.)
Home preserves (pH 5 and above) frequent
source of botulism
 Not formed in pH below 4.7
 Molds may shift pH to above 4.7
 Destroyed by boiling 10 min
 Treatment of Botulism NONE

BOTULISM PREVENTION
 Preservation of foods at pH below 4.7
 Salt (brine) and sugar
 Nitrites in cured foods (remember the
nitrites/nitrates in hot dogs, cured
ham, processed meats)
 Boiling food 10 min
INFANT BOTULISM
 Predominant
form in the USA
 75-100 cases/year in the USA
INFANT BOTULISM (cont.)
 Less
than 6 months old children
 Associated with ingestion of honey
 Honey has endospores in it naturally
bees pick up the endospores from the
flowers
 Immature intestinal microflora of infants
leads to infant botulism

children may receive medical attention because of
symptoms such as constipation, poor sucking action, a
weak cry, and a general, progressive muscle
weakness.
Infant botulism detection tests!!
The diagnosis is confirmed by the
detection of the organism or its toxin in
the infant’s stool
 Toxin isolation and identification are
accomplished via mouse lethality testing,
with typing (type C or D toxin) confirmed
by neutralization of toxin by specific sera
(antibodies—immunoglobulins)

Where are these endospores
commonly found?

More than 90% of reported cases (infant
botulism) in the USA come from California,
Utah, and southeast Pennsylvania; this is
likely a consequence of high
concentrations of C. botulinum spores in
the soil of these regions
WOUND BOTULISM
C.
botulinum develops in grossly
contaminated wounds
19 cases in 1995
Very common with black tar
heroine users/skin popping
Therapeutic use of botulinum toxin
blepharospasm and strabismus
BOTOX
What is Blepharospasm?
Blepharo means "eyelid". Spasm means
"uncontrolled muscle contraction".
The term blepharospasm can be applied to
any abnormal blinking or eyelid tic or twitch
resulting from any cause, ranging from dry
eyes to Tourette's syndrome to tardive
dyskinesia.
What is Strabismus?
Strabismus, also known as crossed or
turned eye, is the medical term used
when the two eyes are not straight. It
occurs in approximately 2% to 4% of
the population.
GAS GANGRENE
GAS GANGRENE
 Tissue
necrosis (death) from lack of
blood supply
 Caused by C. perfringens
 Neglected wounds (anaerobic
conditions) provide a suitable
environment for C. perfringens growth
Gas gangrene
Clostridium perfringens
GAS GANGRENE (cont.)
Highly lethal if untreated
 C. perfringens ferments muscle proteins and
carbohydrates producing H2 and CO2
 Predisposing factors:

 Dirt
in wound
 Long delay before wound care
 Induced abortion
GAS GANGRENE (cont.)
Predisposing
factors:
Arteriosclerosis
Diabetes
Gas
gangrene
in arm
Bone fracture with
gas in surrounding
muscular tissue
Gas gangrene
in foot
Gas
gangrene
in foot
Gas gangrene in buttocks
TREATMENT

Removal of necrotized (dead) tissue
 Amputation
Hyperbaric O2
 Antibiotics

Hyperbaric chamber for
gas gangrene treatment
Anthrax
Anthrax

Caused by Bacillus anthracis (aerobic;G+; endospore
former)
 commonly found in the soil (South and Central
America, Southern and Eastern Europe, Asia,
Africa, Caribbean and the Middle East)
 primary disease of domesticated and wild animalsparticularly herbivores
 humans become infected when they come into
contact with diseased animals (flesh, bones, hides,
hair and excrement)
 Robert
Koch-1876, 1877 isolated
and obtained a pure culture
 Louis Pasteur-1881, developed a
vaccine
Robert Koch
Koch was a doctor and he had a detailed
knowledge of the human body – something
that Pasteur, as a research scientist – lacked.
 He was also skilled in experiments, the result of
his work in natural sciences
 Qualities that also proved to be important were
his ability to work for long periods of time and
his patience
 However, Koch was also difficult to work with
and could not tolerate anyone telling him that
his theories were wrong

Robert Koch

In 1872, Koch became district medical
officer for a rural area near Berlin. He
started to experiment with microbes in a
small laboratory he had built for himself in
his surgery.
Anthrax vaccine--Pasteur
In France at that time many cattle suffered from
anthrax, a serious disease from which many of
them died.
 after many experiments Pasteur succeeded in
producing a weakened & harmless culture of
anthrax bacteria
 He inoculated cattle & sheep with this giving
them a mild form from which they recovered
 When these animals were introduced with
others who had a severe form they remained
unaffected. They were immune.

Gram Stain-Gram
Positive
Robert
Koch’s
Photos

Human cases of Anthrax are rare: 1/100,000
risk

Three forms:
 Cutaneous-Most common form
 acquired through a cut or abrasion of the skin,
which comes into contact with spores from the
soil or a contaminated animal
 Inhalation acquired by the inhalation of spore-containing
dust where animal hair or hides are handled
 Intestinal- (Speculated)
 consumption of contaminated meat
Cutaneous-Spores germinate, vegetative cells multiply
and a lesion (black=necrotic tissue) develops at the
site of infection
 Extreme cases involve bacteria in the bloodstream
which can be fatal (25%)
 Inhalation-Symptoms may resemble a common cold,
progressing to abrupt fever and chest pain. After
several days, severe breathing problems and shock,
resulting in death (hemorrhage)—leads to 100%
death if left untreated
 Intestinal-Inflammation of the intestinal tract, nausea,
loss of appetite, vomiting, severe diarrhea and death
(25-60%)

Cutaneous Anthrax
Treatment:
Antibiotics
 Effective if given within 24 hours, or before
the bacteria enter the bloodstream
 Penicillin, Tetracyclines, fluoroquinolones
(Cipro)
 Vaccine
 protective antigen (composed of a fraction of
the toxin)
 95% protective
 *No evidence of person-to-person transmission

Anthrax Toxin-Symptoms and disease is caused by a
toxin
 made up of a protease (protein-digesting
enzyme)
 B. anthracis form endospores
 Spores may survive in the soil, water and on
surfaces for many years
 Destroyed by autoclaving, burning, or
chlorination

Biological Warfare
Any disease-causing organism that is used as a
weapon
 Anthrax has particularly useful features to be used
as a weapon
 Stable in the environment (endospores)
 spores that can be inhaled
 once spores are inhaled, vegetative cells grow
and produce lethal toxins
