Bacillus is a genus of gram-positive, spore-forming bacteria that are ubiquitous in the environment. Some Bacillus species are pathogenic to humans and animals, including B. anthracis, which causes anthrax, and B. cereus, which can cause food poisoning. B. anthracis forms durable spores that allow the bacteria to survive for decades in the environment. It causes anthrax, which presents as one of three forms: cutaneous, inhalation, or gastrointestinal. The inhalation form is often fatal if untreated. B. cereus can cause two types of food poisoning - an emetic type or diarrhea type - through the production of enterotoxins. While most Bacillus

1. Bacillus
 Presented by:
Iqbal Danish

3. Characters of Bacillus
 Gram-positive or Gram-variable bacilli
 Aerobic, spore forming
 Large number of species are saprophytes, antharcoides
 Ubiquitous
 Some are motile and some capsulated
 non-pathogenic organisms is B. subtilis-subtilis group
 B. mycoides,
 B.megaterium,
 B.cereus
 Natural habitats:
 Water, soil, decaying matter, dust, air
 Pathogenic species—B.anthracis

4. Laboratory Characteristics of Bacillus
 On blood agar
 Large, spreading, gray-white colonies, with irregular
margins
 Many are beta-hemolytic (helpful in differentiating
various Bacillus species from B. anthracis)
 Spores seen after several days of
incubation, but not typically in fresh clinical
specimens

5. Epidemiology of Bacillus anthracis
 Enzootic in certain countries (e.g., Turkey, Iran,
Pakistan and Sudan)
 Anthrax spores infectious for decades
 Biologic warfare experiments
 Primarily a disease of herbivorous animals
 Most commonly transmitted to humans by direct
contact with animal products (e.g., wool and hair)
 Also acquired via inhalation & ingestion

6.  Still poses a threat
 Importing materials
contaminated with
spores from these
countries (e.g., bones,
hides, and other
materials)
 Usually encountered as
an occupational
disease
 Veterinarians

7. Cultural Characteristics
 Grows rapidly on ordinary
lab. Media
 Nutrient agar,
 blood agar,
 serum agar
 Aerobic
 Temp 35-37 O
C/24 h
 Sporulation under aerobic
conditions at 15-40O
C
 Pink—purple pigment
production in the medium
containing iron salts

8.  On NA, flat, frosted appearance colony
 Roughened edge (Medusa head)
 On serum agar; smooth, mucoid colonies
 In Nutrient broth; flocculent deposits of long
chains
 On blood agar; slight hemolysis

9. Biochemical Characters/ Reactions
 Acid without gas (glu, mal, Saccharose)
 Nitrate to nitrites
 Indole not produced
 VP +ve
 Resistance
 Vegetative killed at 600
C/ 30 minutes
 Spore resist
 Formaldehyde effective

10. Antigens and Toxins
 Capsular polypeptide, somatic protein and
somatic polysaccharide antigen
 Extra-cellular toxin composed of three
components;
 Factor I, II and III
 Oedema factor
 Protective factor
 Lethal factor, respectively)
 Protective antigen binds to cell surface and
functions as receptors for oedema factor and
lethal factor

11. Epidemiology and pathogenesis
 Anthrax disease (wool sorter’s disease)
 Pulmonary
 Skin form
 Incidence high in grazing animals, ingest
spores. Spores go to Lymphoid glands
(through any injury)
 Death due to shock, renal failure and terminal
anoxia
 Two forms
 Peracute
 Acute

12.  In peracute death in 1-2 hours without
symptoms
 In acute, eithir 48 hrs
 Important charc, tarry blood from natural
orifices (Nostrils, mouth, vagina and anus)
 No clotting of blood
 Absence of rigor mortis
 Splenomegaly
 Postmortem?

13. Clinical presentation of anthrax
 Cutaneous form
 95% human cases are cutaneous infections
 1 to 5 days after contact
 Small, pruritic, non-painful papule at inoculation site
 Papule develops into hemorrhagic vesicle & ruptures
 Slow-healing painless ulcer covered with black eschar
surrounded by edema
 Infection may spread to lymphatics w/ local
adenopathy
 Septicemia may develop
 20% mortality in untreated cutaneous anthrax

14.  Inhalation anthrax
 Virtually 100% fatal
(pneumonic)
 Meningitis may
complicate
cutaneous and
inhalation forms of
disease
 Pharyngeal anthrax
 Fever
 Pharyngitis
 neck swelling

15.  Ingestion anthrax
 Virtually 100% fatal
 Abdominal pain
 Hemorrhagic ascites
 Paracentesis fluid may reveal gram-positive
rods

16. B. cereus
 Spore forming
 Gram positive/
 Gram variable
 Epidemiology
 Ubiquitous
 People at risk,
 who use contaminated food
 Penetrating injuries
 Injections

17. Virulence
 Heat stable enterotoxin
 Heat labile enterotoxin
 Spore survive in soil
 Tissue destruction by cytotoxic enzymes
 Cereolysin
 Phospholipase C
 Disease
 Gastroentritis
 Emetic
 Diarrhae
 Eye infection----trauma
 Opportunistic infection

18. Other species
 Bacillus thurigensis
 BT cotton Other GMO’s (genetically modified
organisms)
 Bacillus stearothermophilus
 Spores used to test efficiency of killing in autoclaves