Gram +, large rodoxidase - endosporecatalase + mostly motileoxidative/ fermentative aerobic Habitat widely distributed in the environment because they produce highly endospore

Bacillus anthracis * spore can survive more than 50 years in soil * the plasmid-encoded capsule consist of D-glutamyl polypeptide * plasmid encodes exotoxin * cell wall is largely polysaccharide Anthrax

Virulence factor 1. Capsular antigen * D-glutamyl polypeptide capsule antiphagocyte * capsule establishes infection * non encapsulated mutants are avirulent 2. Exotoxin (protein toxin, heat labile) 3 components

Components of exotoxin Pathogenic Character loss fluidedema release IL-1 from macrophage antiphagocytic cytotoxin of cells death of target cell Factor I FractionName lethal factor II+III edema factor I+II protective antigen Factor II Factor III

Resistance * spore are killed by : autoclaving (121 0 C / 15 min) dry heat (150 0 C / 60 min) boiling (100 0 C > 10 mins) * not susceptible to : phenolic compound alcohol quarternary ammonium disinfectant

Resistance (cont.) * susceptible to : aldehyde ß -propiolactone chlorineethylene oxide * heat fixation of smear does not kill spores

TRANSMISSION animal:ingestion of contaminated feed or water wound infection and arthropod bites humans:skin, wound (malignant carbuncle) inhalation ingestion

PATHOGENESIS AND PATHOGENICITY in vivo * gene encoding capsule and toxins are turned on * antiphagocytic capsule and three toxins * toxin is leukocidal * increase vascular permeability and capillary thrombosis leading to shock related to generalize release of IL – 1

spores germinate in macrophage phagosomal escape replicate & release from macrophage encapsulated bacteria proliferate and resist further phagocytosis

spread to regional lymph nodes reticuloendothelial organs bacteremia and toxaemia pathophysiological effect shock asphyxia death hemorrhagic lymphadinitis

Description: How

Infection in domestic animals Bovine and ovine : (septicemic form) peracute septicemia (death within 1-2 hr.) acute septicemia (death in hr.) chronic infection (rarely observed) Equine : (subacute to acute) * colic and diarrhea * edema at the point of infection (intestine, throat) * acute pharyngitis

Porcine: * infected meat & bone meal * pharyngitis is most common * regional lymphadinitis * cutaneous anthrax “ bull nose ” Canivores: * infected meat * pharyngeal anthrax * similar to porcine * septicemia may occur by tainted meat

Human * percutaneous introduction (malignant carbuncle) * possible subcataneous edema and septicemia * pulmonary edema (inhalation anthrax) hemorrhagic pneumonia meningitis

Vesicle ringBlack eschar

day 2 day 4

ISOLATION AND IDENTIFICATION Sample Collection : * blood aspirated from superficial vessels * aqueous humor * bloody discharges from orifices (direct exam.) * spleen (if carcass was opened)

Direct examination : Blood and organ smears : Gram stain Capsule stain encapsulated, gram+, non-spore, rod FA technique

Culture : common media flat dry “ medusa head ” colonies non-hemolysis, non-motile Animal inoculation (mice, guinea pig) : subcutaneous inoculation of suspected materials hemorrhage, gelatinous exudate at that site engorged spleen encapsulated agent demonstrated in blood and tissues

Immunodiagnosis : Ascoli ’ s test precipitation test Molecular methods : DNA probes, PCR detect specific genes in plasmid-encoded capsule and toxin

Precipitation test

(1) opportunistic infections abortion in cattle mastitis (acute gangrenous) initiators (2) Food poisoning in humans diarrhea (various foods - diarrheal toxin) vomiting (rice - emetic toxin) Bacillus cereus Udder surgery intramammary medications

widespread in the environment associated with food spoilage cause of abortion in cattle & sheep (silage & mouldy hay) diagnostic significance when isolated in heavy pure culture from foetal abomasal contents Bacillus licheniformis