BACILLUS Flashcards
Large, ‘boxcar’ shaped, ± spores
Bacillus, Clostridium
Small, pleiomorphic, angular arrangements
Corynebacterium
Cutibacterium
Lactobacillus
Listeria
Beading, filamentous
Nocardia, Actinomyces
Spore-forming, aerobic or facultatively anaerobic, rod-shaped bacteria and isolated from the soil
BACILLUS
BACILLUS SPECIES
o Bacillus anthracis
o Bacillus cereus
o Bacillus thuringiensis o Bacillus mycoides
large, boxcar-shaped, gram-positive
rods with clear, unstained, central spores or
“empty spaces”
Bacillus on microscopy
Motile with peritrichous flagella except for
Bacillus anthracis and Bacillus mycoides
Species only form endospores aerobically
Survive in extreme environment
Bacillus
(+) catalase
ferments glucose
hydrolyzes starch
Biochemical Test of Bacillus
D-glutamic acid capsule and
protein exotoxins
VF of Bacillus
Thiamine B
Growth Factor of B anthracis
Gram-positive, large,
encapsulated and square-ended rod; has “bamboo fishing rods” appearance on the unstained central spore
Microscopy of Bacillus anthracis
colonies have “Medusa head” appearance with swirling projections; are non- haemolytic; and “beaten egg white” appearance when inoculating loop is used.
Bacillus anthracis on BAP
Malignant pustule, sputum and blood
Specimen for B. a
isolated from normally sterile site such as blood, lung tissue and CSF.
B. anthracis
o Used of old culture in Gram staining:
Gram variable
o Spore stains: Malachite green and
McFadyean stain
o Capsule stain: India ink (blood and
CSF)
o Fluorescent microscopy: rapid
presumptive diagnosis
Staining
Used of old culture in Gram stainin
Gram variable
Spore stains
Malachite green and
McFadyean stain
Capsule stain
India ink (blood and
CSF)
rapid
presumptive diagnosis
Fluorescent microscopy
: BAP, CAP, egg yolk
agar (EYA), Phenylethyl alcohol (PEA),
Polymyxin-lysozyme-EDTA-thallous
acetate (PLET), bicarbonate agar, and
nutrient broth
Culture media used in Bacillus anthracis
application of heat or alcohol shock
technique before plating on media
Enrichment and Selective technique
recommended for identification of
B. anthracis in fecal specimen
PEA
used in isolating
Bacillus from contaminated specimen
PEA and PLET
determine B. anthracis has
produced lecithinase
EYA
inverted pine tree
appearance.
Gelatine Medium
Disease primarily affects: goats and sheep, by
feeding on plants that are contaminated with the
spores.
Anthrax
inhalation of spores during exposure to
infected animals and contaminated animal
products, or cuts through skin
MOA for anthrax
: cause signs and symptoms
Exotoxins
o spores are inoculated into a lesion on
the intestinal mucosa following their
ingestion.
Gastrointestinal anthrax
o inhalation of spores into the pulmonary
parenchyma
o resembles URTI with mild fever,
dyspnea
o this is usually acquired when getting
sheep’s fur.
Pulmonary anthrax/Woolsorter’s disease
o Acquired thru skin cuts and abrasions
o Small papule 2-5 days after exposure
o Appearance: “black eschar”, black,
necrotic and painless central area that
does not produce pus.
Cutaneous anthrax
o Detects thermostable anthrax antigens
o (+): formation of precipitin band after
less than 15 minutes
Ascoli Test (Precipitin test)
Bacillus (catalase +); Clostridium
(catalase -)
Catalase Test
Variable (anthrax)
Oxidase Test
(+) cell wall polysaccharide and capsule
antigen.
DFA Test (Direct Fluorescent Antibody Test)
Causes food poisoning due to the ingestion of
contaminated cooked rice dishes or other food
products
BACILLUS CEREUS (“FRIED RICE” BACILLUS)
- Commonly encountered Bacillus in opportunistic
infections that causes eye and ear infection. - Exhibits motility and resistant to penicillin
BACILLUS CEREUS (“FRIED RICE” BACILLUS)
uspected food
(>105cells/gram)
Best specimen for testing for Bacillus cereus
Enterotoxins (heat-stable
and heat-labile), cerelysin, phospholipase C and
pyogenic toxin
VF of B. cereus
Ferments salicin; (+)
lecithinase
Biochemical test of B. cereus
large and feathery; spreading growth;
have a frosted-glass appearance and bhaemolytic
B. cereus on BAP
o Heat labile enterotoxin
o Ingestion of contaminated meat, poultry
and vegetables. IP: 8 to 16 hrs
Diarrheal type
o Heat stable enterotoxins
o Ingestion of improperly cooked rice
Emetic Type
o Most commonly encountered laboratory
contaminant
o Halophilic organisms, up to 7% NaCl
o Source of Bacitracin antibiotics
o Cause: Eye infection among prohibited
drug users
o BAP: large, flat, and dull with groundglass appearance; maybe b-haemolytic
and exhibit pigment (pink, yellow,
orange or brown)
o Biochemical test: Ferment mannitol,
xylose and arabinose
Bacillus subtilis (Hay Bacillus)
o biological indicator: sterilization method
o BAP: large and moist; blister-like
appearance and b-haemolytic
Bacillus pumilus
o insect pathogens
o produces parasporal crystals that can
be utilized as pesticide
Bacillus thuringiensis
- Grow aerobically or anaerobically
- Not part of normal flora and not highly
contagious - Non-motile, halophilic organism can withstand
up to 7% NaCl - Used as biological weapon of mass destruction
- Grows in low pH (<6.0) environment, produce
lecithinase and ferments glucose
Bacillus anthracis
