Aerobic Gram positive rods or
Bacilli
Bacillus
Bacillus
Classification
All are large Gram-positive bacilli
They are aerobic
Form endospores (exposure to O2 will induce sporulation)
Most are found in dust and soil
Bacillus anthracis is the major pathogen in the group
Classification
All are large Gram-positive bacilli They are aerobic
Form endospores (exposure to O2 will induce sporulation)
Most are found in dust and soil
Bacillus species
Bacillus species
2.0µm
B. cereus B. subtilis
B. sphaericus B. circulans
B. anthracis B. cereus B. subtilis
B. sphaericus
B. amyloliquefaciens B. licheniformis
Bacillus anthracis
Bacillus anthracis
G+ve bacilli with square cut ends
Form endospores
Non-motile
Capsule made of polypeptide
The capsule is not found in cultured bacteria unless the bacteria are grown on bicarbonate containing media and in the presence of increased CO² concentrations.
Is very similar to B. cereus (cause of food borne
intoxication) and B. thuringiensis (produces crystals toxins that kill insects and nematodes).
Differences:
B. anthracis creates no hemolytic zone on blood agar
B. cereus creates hemolysis on blood agar
G+ve bacilli with square cut ends Form endospores
Non-motile
Capsule made of polypeptide
The capsule is not found in cultured bacteria unless the bacteria are grown on bicarbonate containing media and in the presence of increased CO² concentrations.
Is very similar to B. cereus (cause of food borne
intoxication) and B. thuringiensis (produces crystals toxins that kill insects and nematodes).
Differences:
B. anthracis creates no hemolytic zone on blood agar
B. cereus creates hemolysis on blood agar
Bacillus sp. On BA
Bacillus sp.
On BA
B. anthracis B. cereus
Gelatin is liquid in warm water, and changed to gel when cooled.
It become liquid when hydrolized by gelatinase enzyme, and remained liquid even when cooled
1 1
2 2
Bacillus anthracis
Bacillus anthracis
Virulence factors
Capsule helps organism to resist phagocytosis
Exotoxin is very complex and is produced only when the bacteria is growing in animal tissues (37 ̊C and presence of CO2)
Toxin production is mediated by a temperature sensitive plasmid.
The toxin consists of three protein components
(maximum toxicity occurs when all three components are present).
Virulence factors
Capsule helps organism to resist phagocytosis
Exotoxin is very complex and is produced only
when the bacteria is growing in animal tissues (37 ̊C and presence of CO2)
Toxin production is mediated by a temperature sensitive plasmid.
The toxin consists of three protein components
(maximum toxicity occurs when all three components are present).
The source of the anthrax toxin
Fully virulent strains of B. anthracis carry two large plasmids,
pXO1 (187kbp) encodes the different components of the
anthrax toxin (Three components PA, LF, EF)
pXO2 (97kbp) encodes the capsule, a polymer of poly-D-glutamic acid (polypeptide), that enables the bacteria to evade the host immune defences
The source of the anthrax toxin
Fully virulent strains of B. anthracis carry two large plasmids,
pXO1 (187kbp) encodes the different components of the
anthrax toxin (Three components PA, LF, EF)
Bacillus anthacis
Bacillus anthacis
Protective antigen (PA) reacts with host cell tissue receptors activated and it binds LF and EF to allow entry of LF and EF into the host cells.
Lethal factor (LF) Both PA and LF are required for lethal activity.
Edema factor (EF) Both PA and EF are required for edema to occur.
Protective antigen (PA) reacts with host cell tissue receptors activated and it binds LF and EF to allow entry of LF and EF into the host cells.
Lethal factor (LF) Both PA and LF are required for lethal activity.
Edema factor (EF) Both PA and EF are required for edema to occur.
PA, LF, EF factors alone exhibits no significant biological activity in an animal.
Combination of the toxin factors:
the following results in experimental animals: PA + LF = lethal toxin
PA + EF = edema toxin
EF + LF is inactive (Why???????)
PA + LF + EF produces edema and is lethal
Bacillus anthracis
Bacillus anthracis
Disease:
1- Anthrax
Is essentially a disease of animals who acquire the organism by ingestion or inhalation of spores.
The spores are extremely resistant to adverse chemicals and physical environments.
They may remain a source of infection in soil for 2-3 years.
Man acquires anthrax usually from contact with animal products
Disease:
1- Anthrax
Is essentially a disease of animals who acquire the organism by ingestion or inhalation of spores.
The spores are extremely resistant to adverse chemicals and physical environments.
They may remain a source of infection in soil for 2-3 years.
Bacillus anthracis
Bacillus anthracis
2- Cutaneous anthrax
Spores enter through a cut, germinate, and vegetative cells multiply;
Acute host inflammatory response, but the capsule prevents phagocytosis;
Exotoxin release and invasive damage result in rapid development of a malignant pustule
Occasionally, without treatment, the organism will disseminate to cause septicemia and death in a few days
Vascular injury with edema, hemorrhage
Death results from respiratory failure and anoxia caused by actions of the toxin on the central nervous system (toxemic degeneration).
2- Cutaneous anthrax
Spores enter through a cut, germinate, and vegetative cells multiply;
Acute host inflammatory response, but the capsule prevents phagocytosis;
Exotoxin release and invasive damage result in rapid development of a malignant pustule
Occasionally, without treatment, the organism will disseminate to cause septicemia and death in a few days
Vascular injury with edema, hemorrhage
Death results from respiratory failure and anoxia caused by actions of the toxin on the central nervous system (toxemic degeneration).
Papule (on fore arm)
4 days after exposure Necrotic ulcer5 days after exposure
Dark eschar (Black scap)
Bacillus anthracis
Bacillus anthracis
3- Pulmonary (Woolsorter‘s disease)
Spores are inhaled and germinate in the lungs where they multiply and spread to cause a fatal septicemia or meningitis.
Requires high inoculum, man resist over 2,000 inhaled spores/day
This is the most serious form of the disease.
3- Pulmonary (Woolsorter‘s disease)
Spores are inhaled and germinate in the lungs where they multiply and spread to cause a fatal septicemia or meningitis.
Requires high inoculum, man resist over 2,000 inhaled spores/day
This is the most serious form of the disease.
Pulmonary (Inhalation) anthrax or woolsorter’s disease
Symptoms
• The disease begins with high fever and chest pain.
• Results in systemic hemorrhagic pathology and is often fatal (death in 2 or 3 days if untreated)
• Lesions in mediastinal lymph nodes. • Fatal 90% in untreated case
Diagnosis
4- Gastrointestinal anthrax
As in cutaneous anthrax, the organism probably invade the mucosa through a preexisting lesion
Symptoms
Acute gastro-enteritis, abdominal pain, vomit blood, severs diarrhoea, septicemia
-The 2001 anthrax attacks in the US started on Sept. 18, 2001.
Letters containing anthrax bacteria were mailed to several news media offices and to 2 U.S. Senators. - 5 people died from inhalation anthrax and 17 were sick.
-The 2001 anthrax attacks in the US started on Sept. 18, 2001.
Letters containing anthrax bacteria were mailed to several news media offices and to 2 U.S. Senators. - 5 people died from inhalation anthrax and 17 were sick.
2001: anthrax letters (as weapon)
Anthrax - Diagnosis
Anthrax - Diagnosis
Specimen
Aspirate or swab from cutaneous lesion
Blood culture
Sputum
Laboratory investigation
Gram stain
Culture
Identification of isolate (and PCR identification)
Specimen
Aspirate or swab from cutaneous lesion
Blood culture
Sputum
Laboratory investigation
Gram stain
Culture
Treatment
Treatment
Antibiotic susceptibility and treatment
Penicillin or tetracycline
Vaccine
A short-term PA vaccine is available for industrial workers and others at high risk.
Antibiotic susceptibility and treatment
Penicillin or tetracycline
Vaccine
Bacillus cereus
Bacillus cereus
B. cereus is also an opportunistic pathogen that has been cultured from cases of septicemia, endocarditis, meningitis, wound infections,
pneumonia, and fulminant eye infections
In addition to the enterotoxin that bacteria may produce, a dermonecrotic and a lethal toxin,
hemolysins, lecithinase, proteases, and nucleases may be involved in its pathogenesis
Clindamycin with or without gentamycin may be used for treatment of infections
B. cereus is also an opportunistic pathogen that has been cultured from cases of septicemia, endocarditis, meningitis, wound infections,
pneumonia, and fulminant eye infections
In addition to the enterotoxin that bacteria may produce, a dermonecrotic and a lethal toxin,
hemolysins, lecithinase, proteases, and nucleases may be involved in its pathogenesis
Other Bacillus species
Bacillus subtilis, and occasional other species may occasionally cause opportunistic infections. Bacillus cereus is a major cause of
enterotoxin food poisoning;
The toxin is protein in nature and can be destroyed by heating;
Food poisoning occurs after ingestion of pre-formed toxin;
Vomiting occurs 1-5 hours after ingestion
Other
Bacillus species
Bacillus subtilis, and occasional other species may occasionally cause opportunistic infections. Bacillus cereus is a major cause of
enterotoxin food poisoning;
The toxin is protein in nature and can be destroyed by heating;
Food poisoning occurs after ingestion of pre-formed toxin;
Gastroenteritis
Gastroenteritis
Bacillus cereus
clinical presentation
Incubation period < 6 hours Severe vomiting
Lasts 8-10 hours
Incubation period > 6 hours Diarrhoea
Lasts 20-36 hours
