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Corynebacterium
Bacillus
General
● Gram-positive
● Aerobic or facultative anaerobic
● Catalase positive, oxidase negative, nonspore forming
● Nonmotile except C. aquaticum
- Pathogenic species are nonmotile
Gram
+
O2
Catalase + Oxidase -
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Morphology
● Pleomorphic rod shaped
- Individual cells may be swollen, clubbed,
Palisades of parallel cells
Angular clusters resembling “Chinese letters”
八eight
人people
Memory Game
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Presumptive Identification
Gram stain
Positive ?Negative ?
Morphology
Cocci ? Bacilli (rod)?
Spore formation
Positive ? Negative ?Bacillus
Catalase
Positive ? Negative ?
Motility
Positive ? Negative ?Listeria
C. renale
● Three species (renale, cystitidis and pilosum) were formerly
classified as a single species: “renale is the major”
● Morphology: short rods, thicker at one end
● Growth: favored by blood or serum, grows well in sterile urine
● “Urease” positive: (NH2)2CO + H2O → CO2 + 2NH3
● Habitat: Widely distributed in the urethra and prepuce in normal
cattle and sheep (considered as normal flora)
● Transmission: May be venereal and indirect
● Disease
- Cattle: Infections are almost always in cows
Ascending infection of the urinary tract, cystitis, pyelonephritis
Enlarged kidney, bloody urine
- Sheep: ↑Protein (diet) Urea (urine) Ammonia (by urease)
Ammonia irritates to the mucosa of prepuce of male sheep
(mild irritation to severe inflammation and blockage of the prepuce)
● Treatment: Penicillin (effective if given early in the disease)
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C. renale: Story
Habitat: Normal flora in
the lower urogenital tract
(Urethra and Prepuce)
Bladder
Kidney
Pennis (pizzle rot)
Venereally
Well surviving in soil
Indirectly ???
Penicillin
C. pseudotuberculosis
● Morphology: Pleomorphic, short rod, coccoid in some isolates
● Biochemical: Urease pos.
● Pathogenesis
- A facultative intracellular parasite
- Phospholipase D: an exotoxin associated with spread
within the host
- Surface lipid: resistance to killing by macrophages
● Transmission
- Discharges from pus containing bacteria
- The bacteria residing in soil may enter via abraded mucosa or
inhalation
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C. pseudotuberculosis:
In sheep and goats
● Caseous lymphadenitis (inflammation of a lymph node)
- Also called “Cheesy gland”: dryish pus
- Two forms
1) Superficial (abscesses of lymph node)
:Visible under the skin near the lymph glands
2) Visceral (abscesses of
internal organs)
- Metastatic lesions
- Inhalation
lung infection
● Ulcerative lymphangitis (inflammation of a lymphatic vessel)
- Infection occurs in lower limbs
- Usually, only one leg is involved
● Pectoral abscesses
- Develop abscesses in their pectoral muscles
Swell and resemble a pigeon's chest “Pigeon fever” (horses)
Bovine ulcerative lymphangitis
Hi guy!, are we siblings?
C. pseudotuberculosis:
In horses and cattle
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C. pseudotuberculosis
● Diagnosis
- Isolation of C. pseudotuberculosis
- ELISA
- PCR
● Treatment
- Drainage of the abscesses
- Antibiotic control is not easy:
because bacteria stay protected inside abscesses
- Penicillin may prolong the disease by delaying abscess maturation
● Vaccination
- Vaccination is recommended
- Live attenuated vaccine from Brazil
with good (83%) protection
C. pseudotuberculosis
Direct contact
Bacterial release to soil Contact or inhalation
Ulcerative lymphangitisPigeon fever
Caseous lymphadenitis
Antibioticslittle effect
Vaccination is advised
Bang!
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C. diphtheriae
● Human pathogen
-Diphtheria: Upper respiratory infection especially
in kids under 4 yrs
● Diphtheria toxin
- Prevents protein synthesis cause cell death
- Associated with bacteriophage encoding
the toxin (tox+)
● Vaccination: DPT (Diphtheria-Pertussis-Tetanus)
- routine vaccination program in developed countries
- only 10% of children in developing countries
(1 million deaths per year)
● Treatment: Administration of antitoxin is the only successful method
Diphtheria toxin
Lysogenic β-pahge
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C. ulcerans
● Disease
- Pharyngitis in humans
- Often isolated from bovine mastitis cases
● Able to produce diphtheria toxin
- When lysogenizied by tox-carrying phage
serious illness to unvaccinated individuals
Pathogenic corynebacteria
C. renale group
C. renale (type I) Cattle Bladder, kidney infections
Sheep Penis infections (pizzle rot)
C. pilosum (type II) Cattle Bladder and kidney infections
C. cystitidis (type III) Cattle Severe bladder infection (cystitis)
Rare kidney infection
C. pseudotuberculosis Sheep, Goats Caseous lymphadenitis
Horses, Cattle Ulcerative lymphangitis, ventral abscesses
C. ulcerans Cattle
Human
Mastitis
Pharyngitis
C. diphtheriae Human Diphtheria
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Do you know?
Q: What Corynbacterium is involved in ovine caseous lymphadenitis?
1. C. renale2. C. diphtheriae
3. C. pseudotuberculosis
4. C. ulcerans
Corynebacterium
Bacillus
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Bacillus
● Gram-positive, large rods
● A large number (>50) of species
and widespread in nature,
but majority are non-pathogenic
● Endospore formation
● Aerobes or facultative anaerobes, catalase positive
● Majority are motile (except for B. anthracis and B. mycoides)
Flagellar staining (by Leifson's Method) of various Bacillus species (CDC)
Identification
Gram stain
Positive Negative
Morphology
Cocci Bacilli (rod)
Spore formation
Positive Negative Bacillus
Catalase
Positive Negative
Motility
Positive Negative Listeria Corynebacterium
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B. anthracis: general
● Cause “anthrax” - A severe disease affecting almost all
mammalian species
● Non-motile, non-hemolytic
● Capsules will form in cultures
grown on media containing
bicarbonate
or 50% serum agar in CO2
Medusa headBicarbonate plate
B. anthracis: Anthrax
● Cattle and sheep
- Herbivores are highly susceptible
- Often developing a rapidly
fatal septicemic disease
Sudden death
● Pigs and horses: Moderately susceptible
● Carnivores: Comparatively resistant
● Birds: Almost totally resistant
What about me?
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B. anthracis: Anthrax
● Humans
1. Malignant carbuncle: cutaneous anthrax
- organisms is introduced through a wound
develop dark painless lesions
if untreated bacteremia and death
2. Gastroenteritis
- Rare, but from eating infected carcasses
3. Respiratory form (woolsorter’s disease)
- Inhalation of spores by those who
handles hides, wool, and hair
from infected animals
- Preferred route for biowarfare
B. anthracis: Endospore
● Endospore formation
- Important in persistence and spread of anthrax
- Spores are resistant to heat, acid, etc.
:Spores of B. anthracis can
survive for more than 50 years!
Spores in soil
Germination
Septicemia
Toxemia Host death
Spread of spores
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B. anthracis: Virulence Factors
● Two large plasmids (pXO1 and pXO2) carry the genes for
anthrax toxins and capsule
pXO1pXO2Capsule Anthrax toxins
B. anthracis: Anthrax toxins
● Protective antigen (PA)
- Transports toxin components to the host cell cytosol
● Edema factor (EF)
- Adenylate cyclase (ATP cAMP)
- cAMP ↑ accumulation of fluids
edema
● Lethal factor (LF)
- LF is a protease
- Proteolytically cleaves MAPKKs,
intracellular signaling proteins
causing cell death
Inhibit the regulation of
immune response
(Adenylate cyclase) (protease)
acidification
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B. anthracis: Capsule
● Virulence factors
- “Polypeptide” capsule (poly-D-glutamic acid)
cf. capsule is usually “polysaccarides”
● Resistance to phagocytosis
- Unencapulated bacilli are more susceptible to phagocytosis
Journal of Bacteriology (1998) 180, 52-58
Peptidoglycan
S-layer (Surface-layer):
consists of two surface proteins (EA1 and Sap)
Capsule
FA test of capsule
B. anthracis: Diagnosis
● Performing necropsies on animals dead of anthrax is
“undesirable” since exposing the tissues to the atmosphere
will result in the formation of large numbers of spores
may contaminate the environment for many years
● Aspirate the aqueous/blood discharge for culture
- B. anthracis grows readily on blood agar (non-hemolytic)
- Produces capsules on BHI agar containing 0.5%
sodium bicarbonate incubated in 10-30% CO2
● PCR
- To detect genes encoding the toxins and the capsule
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B. anthracis:
Prevention and Treatment
● Vaccniation
- Spore vaccines and avirulent nonencapsulated strain were
used successfully
- Use of the vaccine in livestock has declined markedly in the US
due to the decreased incidence
● Antibiotics
- Penicillin: effective
Tetracycline
- Ciprofloxacin is used in humans
B. cereus
● B. cereus
-Human: Food poisoning often associated with
cooked rice held at improper temperatures
-Cattle: Mastitis occasionally
-Dogs: Food poisoning when fed highly
contaminated canned food
● B. licheniformis
- Associated with abortions in cattle and sheep
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Bacillus & Diseases
B. anthracis Cattle, sheep Fatal peracute or acute septicemic anthrax
Humans Skin, pulmonary and intestinal forms of anthrax
Pigs, dogs, cats Subacute anthrax with edematous swelling in
pharyngeal region
Horses Subacute anthrax with localized edematous
swellings of the head, neck, shoulders, throat
B. cereus Cattle Mastitis (rare)
Humans Food poisoning
B. licheniformis Cattle, sheep Sporadic abortion
Do you know?
Q: What is not the virulence factor of B. anthracis?
1. Toxin production
3. Spore formation
2. Bacterial motility
4. Capsule