1. PowerPoint ® Lecture Slides for M ICROBIOLOGY Pathogenic Gram-Positive Bacilli (Bacillus)

2. Gram-positive bacilli, that occur singly, in pairs, or in chains It is an aerobe and facultative anaerobe They are non-motile and capsulated inside the body Forms endospores outside the body Spores are central and oval Anthracoides or non-pathogenic members include Bacillus subtilis, Bacillus mycoides & Bacillus mesentericus Bacillus stearothermophilus is thermophilic Bacillus anthracis is a strict pathogen of animals and humans Bacillus

3. Bacillus anthracis Anthrax is primarily a disease of herbivores, but humans can contract the disease from infected animals Humans contract the bacteria via one of three routes Inhalation of spores Inoculation of spores into the body through a break in the skin Ingestion of spores

4. Pathogenicity Anthrax toxin (oedema factor, protective antigen, lethal factor) Capsule made of D-glutamic acid Diseases Anthrax is the only disease caused by Bacillus anthracis Anthrax can have three clinical manifestations Gastrointestinal anthrax Rare in humans Intestinal hemorrhaging and eventually death Pathogenicity and Diseases

5. Cutaneous anthrax (hide porter’s disease) Produces a painless ulcer called an eschar (malignant pustule) and toxemia (20% fatal) Inhalation anthrax (wool sorter’s disease) Spores germinate in the lungs and secrete toxins that are absorbed into the bloodstream High mortality rate (100% down to 50%) Pathogenicity and Diseases

6. Epidemiology Primarily a disease of herbivores (zoonotic) Endospores contaminate the soil and remain viable for many years Humans get infected through damaged skin (cuts and scratches) in contact with infected carcasses, bones, hides, hairs and skins of animals Or infection through inhalation of spores (rare) Biological warfare

7. Diagnosis Presence of large, nonmotile, Gram-positive capsulated bacilli in clinical samples of the lungs or skin Treatment Penicillin, Ciproflaxacin and many other antimicrobials are effective against B.anthracis It can be deadly even after treatment Diagnosis and Treatment

8. Prevention Control the disease in animals (vaccination, burning or deep burying in lime pits) An anthrax vaccine is available but requires multiple doses and boosters Destroy spores on animal hairs

9. Bacillus cereus An aerobic, spore forming Gram positive rod Found in soil and on raw and dried foods Causes food borne intoxication and opportunistic infections Spores are not killed during cooking and they germinate in the unrefrigerated food There is an emetic type of food poisoning caused by a heat stable enterotoxin associated with rice dishes (1-6 hrs) And a diarrheal type caused by heat labile enterotoxin associated with meat dishes (8-16 hrs) Can also cause endophthalmitis