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

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Presentation on theme: "Gram +, large rodoxidase - endosporecatalase + mostly motileoxidative/ fermentative aerobic Habitat widely distributed in the environment because they."— Presentation transcript:

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

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5 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

6 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

7 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

8 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

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

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

11 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

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

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

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15 Description: How

16 Infection in domestic animals Bovine and ovine : (septicemic form) peracute septicemia (death within 1-2 hr.) acute septicemia (death in 49-96 hr.) chronic infection (rarely observed) Equine : (subacute to acute) * colic and diarrhea * edema at the point of infection (intestine, throat) * acute pharyngitis

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18 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

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

21 Vesicle ringBlack eschar

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

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

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27 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

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

31 Precipitation test

32 (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

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34 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

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