Bacillus AnthracisAnthrax

Bacillus Anthracis From greek word

“anthrakos” Large (1 - 1.2µm in

width x 3 - 5µm in length), gram (+)

Non motile Facultative anaerobe Spore forming (oval,

endospores) Polypeptide capsule Produces 3 exotoxins

Endospores Can survive in dry

soil for decades Sporulation requires

oxygen Can be killed by:

Vegetative cells in 60 0 C X 30 min

Spores in 100 0 C X 10 min

4% Formaldehyde 4% KMnO4

Hypochlorite ( 0.5%)

Natural Infection Sources Primarily domesticated and wild animals

(sheep, cows, horses, goats) Soil rich in organic matter (pH < 6.0) in regions

where dramatic changes occur in climate Streams, insects, wild animals, birds,

contaminated wastes Undercooked meat Contact with flesh, bones, hides, hair, &

excrement Cutaneous & inhalational infections are most

common

Thos who are at increased risk Tanneries Textile mills Wool sorters Bone processors Slaughterhouses Laboratory workers Military

Biological Weapon Germany (1915) Manchuria (1937) Swerdlowsk, Russia (1979) South Africa (1978-1980) Tokyo (1983) USA, Washington (2001)

Forms of Anthrax Cutaneous anthrax

Skin Most common Spores enter to skin through small lesions

Inhalation anthrax Spores are inhaled

Gastrointestinal (GI) anthrax Spores are ingested Oral-pharyngeal and abdominal

Pathogenesis The infectious dose of B. anthracis in humans

is unknown (though for primates the LD50 is 8,000-10,000 )

Virulence factors are Capsule 3 toxins (Edema factor (EF), Lethal factor (LF) and

Protective antigen (PA))

Capsule Glycocalyx. Sticky, gelatinous polymer external to

cell wall. pX02 plasmid Made up of poly-D-glutamic acid Non-toxic on its own A-B model of toxicity. Two proteins must combine

to create the toxic complex. Protective antigen is the common protein and both EF and LF need PA to get into the cell and cause damage.

Only encapsulated B. anthracis virulent Most important role during establishment of

disease. Protects against phagocytosis & lysis during vegetative state.

Toxins pX01 plasmid PA, EF & LF (50% of proteins in the organism) A-B model

PA+LF lethal activity EF+PA edema EF+LF inactive PA+LF+EF edema & necrosis; lethal

Protective antigen (PA, 83kDa) Pag gene Binds to receptor & helps internalize other 2 proteins

Edema factor (EF, 89 kDa) Cya gene Adenylate cyclase Affects all cells

Lethal factor (LF, 87 kDa) Lef gene Metalloprotease Cleaves mitogen activated protein kinase kinsase (MAPKK) Affects only macrophages

Stages of infection Encounter: organism and body surfaces

Adhesion: generalized and receptor-specific

Initial multiplication in situ colonization

Invasion breaching of anatomic barriers

Lymphatic stage invasion of bloodstream

Generalized infection, metastases local colonizations, “tropisms” of certain organisms

Pathogenesis

Abrasion, inhalation, ingestion

IntroducedPhagocytosed by

Macrophages Regional LNs

Germinate inside macrophages

Vegetative FormsRelease

Multiply in lymphaticsBlood stream10 7 to 10 8/ml

SepticemiaDeath

Phases of symptoms

1st phase (within 7 days)

2nd phase (within 2-3 days)

Fever (> 37,7°C/100°F) Chills or night sweats Headache, cough, chest

discomfort, sore throat Joint stiffness, joint

pain, muscle aches Shortness of breath Enlarged lymph nodes,

nausea, loss of appetite, abdominal distress, vomiting, diarrhea

Meningitis

Breathing problems, pneumonia

Shock Swollen lymph

glands Profuse sweating Cyanosis (skin turns

blue) Death

Cutaneous Anthrax 95% human cases are cutaneous infections Incubation period 2-3 days Small, pruritic, non-painful papule at inoculation

site Papule develops into hemorrhagic vesicle (24-48

hrs) & ruptures Slow-healing painless ulcer (d=1-3 cm) covered

with black eschar, surrounded by edema Infection may spread to lymphatics causing local

adenopathy Septicemia may in 20% of cases 20% mortality in untreated cutaneous anthrax

Cutaneous Anthrax

Inhalation Anthrax Incubation: 1 to 7 days with acute onset (may develop in a

few hours) Very high doses of bacteria (bio-weapon aerosoles) Initial phase

Nonspecific (mild fever, malaise) Second phase

Severe respiratory distress Fever, dyspnea, cyanosis, rales, tachycardia, feeble pulse,

hypotension, mediastinal widening, eventual death Vomiting, sweating, axiety

Lesions in mediastinal lymph nodes, carried there by alveolar macrophages, causing edema, toxemia, bacteremia

Case fatality: 75 to 90% (death in 2 or 3 days if untreated)

Inhalation Anthrax

Widened mediastinum on x-ray

GI Anthrax

Oropharyngeal Abdominal (common)

Caused by deposition and germination of spores in the upper gastrointestinal tract

Local lymphadenopathy, edema, sepsis develop after an oral or esophageal ulcer

Caused by deposition and germination of spores in the lower gastrointestinal tract, which results in a primary intestinal lesion

Abdominal pain and vomiting appear within a few days after ingestion

Incubation: 2 to 5 days Severe gastroenteritis common (due to

undercooked & contaminated meat) Case fatality rate: 25 to 75%• Mucosal lesion (lesions are edematous,

with black eschar) to the lymphatic system Nausea, anorexia, vomiting, fever Progresses to severe abdominal pain and

bloody emesis and diarrhea Ascites may develop on day 2 - 4 Death 2 to 5 days after onset of symptoms Rare in developed countries

Diagnosis Gram stain Culture of B. anthracis from the blood, skin

lesions, vesicular fluid, or respiratory secretions

X-ray and Computed Tomography (CT) scan Rapid detection methods

- PCR for detection of nucleic acid- ELISA assay for antigen detection- Other immunohistochemical and immunoflourescence

Examination

Treatment • Penicillin is drug of choice (ciprofloxacin,

erythromycin, chloramphenicol, doxycycline) 60 days

• Vaccine (for laboratory workers, livestock handlers, active duty military members) BioThrax/Anthrax vaccine

• Do not incise lesions• Eschar is not dangerous after treatment• The patient must remain hospitalized until fully

cured

Prevention Annual animal vaccination Disposal of animal carcasses: disinfect with

oil, burn, bury deep, covered with quicklime. Spores will not form inside the carcass, and

putrefaction kills the Bacillus. Flies feeding on incoagulable blood may be a problem.

Gloves, masks, disinfection of materials. Health edu Death, ilness reports

Bioterrorism‘First choice’ weapono “Poor Man’s Nuke”o Availabilityo Silent, unnoticeableo Deniabilityo Slow actiono Highly lethalo Non-contagiouso Prevention (enemy can easily vaccinate

themselves prior)o UV resistant

Category A Biological weaponHigh-priority agents include organisms that pose a risk to national security because they :

· can be easily disseminated or transmitted person-to-person;

· cause high mortality, with potential for major public health impact;

· might cause public panic and social disruption; and

· require special action for public health preparedness

These agents include: Bacteria: Bacillus anthracis

(anthrax); Yersinia pestis (plague); Clostridium botulinum toxin (botulism); Francisella tularensis (tularaemia);

Filoviruses: Ebola hemorrhagic fever, Marburg hemorrhagic fever; and

Arenaviruses: Lassa (Lassa fever), Junín (Argentine hemorrhagic fever) and related viruses