species; Gram-positive or Gram-variable bacilli 60 (Large (0.5 x 1.2 to 2.5 x 10 um Most are saprophytic contaminants or normal flora

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1 AEROBIC BACILLUS (Lecture (15 Dr. Baha,H,AL-Amiedi Ph.D.Microbiology General Characteristics of Bacillus species; Gram-positive or Gram-variable bacilli 60 (Large (0.5 x 1.2 to 2.5 x 10 um Most are saprophytic contaminants or normal flora Bacillus anthracis Human pathogen Isolation also considered to be clinically significant Zoonosis Bacillus cereus Environmental organism Contaminates food Common cause of food poisoning Bacillus stearothermophilus Tolerates very high temperatures Used for quality control of autoclaves Bacillus anthracis Bacillus anthracis is most important member Produce endospores Aerobic or facultatively anaerobic (Catalase positive (most Rapidly differentiates from Clostridium Bacillus spp. are ubiquitous Soil, water, and airborne Thermophilic (< 75 C) and psychrophilic ((>5-8 C (Can flourish at extremes of acidity & alkalinity (ph 2 to 10 :Transmission cutaneous anthrax result from contact with spores & contact with -1.infected animals & animals products.inhalation anthrax result when spores inhaled-2.gastrointestinal anthrax result when spores are ingested-3 Virulence factors

2 A capsule of D-glutamic acid is antiphagocytic and helps the -1.anthracis to evade the immune system of the host The product of exotoxin-2 Mode of toxin action :Three exotoxins subunit are product protctive Antigen(PA):binds to toxin receptor on cell surface of -1 host &facilitates translocation of the two other exotoxins Edema Factor(EF): is an adenlyate cyclase that increase -2 intracellular camp.stimulating efflux of fluids &ion that result the edema Lethal Factor(LF):it is a mitogen-activted protein kinase -3 kinase(mapkk) protease that disrupts signaling causing cell death &tissue necrosis Pathogenesis and clinical presentations Cutaneous anthrax About 20% mortality Inhalation anthrax High mortality Gastrointestinal anthrax High mortality Clinical Presentation of Anthrax Cutaneous Anthrax human cases are cutaneous infections %95 to 5 days after contact 1 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 mortality in untreated cutaneous anthrax %20 Clinical Presentation of Anthrax Inhalation Anthrax (Virtually 100% fatal (pneumonic

3 Meningitis may complicate cutaneous and inhalation forms of disease Pharyngeal anthrax Fever Pharyngitis Nneck swelling Clinical Presentation of Anthrax Gastrointestinal (Ingestion) Anthrax Virtually 100% fatal Abdominal pain Hemorrhagic ascites Paracentesis fluid may reveal gram-positive rods Epidemiology of Bacillus anthracis Enzootic in certain foreign countries (e.g., Turkey, Iran, (Pakistan,and Sudan Anthrax spores infectious for decades Bacillus cereus Pre formed Large, motile, saprophytic Heat resistant spores (heat and acid stable toxin (Emetic syndrome bacillus (Heat labile enterotoxin (Diarrhoeal disease Lab diagnosis Demonstation of large number of bacilli in food :Laboratory diagnosis Microscopic Examination-1 Smear prepared from exudates,sputum show gram positive bacilli non-bacilli occur in chain Macfadyen test; it is special stain for capsular of bacilli-2.seriological test (Ascoli test): it is rapid precipitate diagnosis test-3 Ascoli test It is used in making rapid diagnosis,the infected tissues are grounded in saline boiled for 5 minutes & filtered. extracted tissue is layered.over anthrax antiserum

4 Zone of precipitate at the junction of tissue extract and antiserum.within 5 minutes at room temperature means test is positive Laboratory Characteristics of Bacillus Cultur ;On blood agar-4 Large, spreading, gray-white colonies, with irregular margins ((Medosa head shape Many are beta-hemolytic (helpful in differentiating various Bacillus (species from B. anthracis Spores seen after several days of incubation in central by smear gram stain examine Animal inoculation: injected guinea pig subcutaneously which die -5 within hours,smear from.heart blood &spleen show gram positive bacilli Treatment Antibiotic such ciprofloxin,doxcycline &other are used for treatment

5 B. anthracis

6 Diseases Associated with Bacillus

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8 Epidemiology of Anthrax in Animal and Human Hosts

9 Anthrax: Cutaneous