Microbiology - Agents of Bioterrorism

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Agents of Bioterrorism

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Biosafety Levels • Do not usually cause disease minimal

safety equipment • Usually those found in high

school/college student labs • Example: Bacillus subtilis

BSL-1 • Known to cause human disease • Encompasses most clinical hospital

laboratories • Ex. HBV and salmonellae

BSL-2 • Known to produce serious disease • Transmitted by respiratory route

• Not identifying directly from specimens(BSL-2) but culturing M. tuberculosis

BSL-3 • Require containment suits • High risk of serious disease • No available treatment

• Ebola BSL-4

Public Health Preparedness

Three categories Category A

• Greatest impact Anthrax, hemorrhagic fevers

Category B Salmonella, ricin, E.coli O157:H7

Category C • Less impact

MDR-TB, hantavirus

See Table 30-1 for full list of examples

Key Indicators of a Potential Bioterror or Biocrime Event

General Characteristics of Bioterror Agents

Easily made Low skill required

Mobile Easy to transport

Transmission Aerosol Person-to-person spread Resistant to decay

History of Criminal Use of Microbial Agents

Salmonella Sprayed onto salad bars in restaurants

Anthrax spores Contaminated letters in NY, DC, and Florida

Ricin toxin

Laboratory Response Network (LRN)

Established in 1999 Community hospitals with microbiology

capabilities Sentinel laboratories

• Must have BSL-2 capabilities Five agents with protocols

– B. anthracis – Y. pestis – F. tularensis – Brucella spp. – Etc.

Laboratory Response Network (LRN) Reference laboratories

Perform confirmatory tests on several biothreat agents

• State public health laboratories • Department of defense medical center laboratories

National laboratories Can perform complex forensic studies Definitive characterization of biothreat agents

• CDC • USAMRIID • National Research Medical Center

Structure of the Laboratory Response Network

Agents of Bioterror

Bacillus anthracis Cutaneous anthrax

• Very few cases Black eschar on skin

Gastrointestinal anthrax • Ingestion of spores in contaminated

food Inhalation anthrax

• Generally none unless bioterror or lab accident

Agents of Bioterror Specimen collection

Swabs from black eschar Blood sample from inhalation and gastrointestinal

anthrax • Colonies have medusa-head morphology

Nonhemolytic

Morphology of Anthrax on Blood Agar, Gram Stain, and Spore Stain

13 Elsevier items and derived items © 2011, 2007 by Saunders, an imprint of Elsevier Inc.

Agents of Bioterror Yersinia pestis

“Black death” Linked to bubonic plague in 1894

• Major vector is flea

Agents of Bioterror

Transmission Bite of infected fleas Handling contaminated materials Inhaling aerosolized bacteria

Weaponized Y. pestis Primarily pneumonic plague

• Person-to-person transmission

Agents of Bioterror

Symptoms Fever, chills, headache, malaise Buboes

• Inflammation of the lymph node causing swelling Bacteria disseminate and cause DIC

– Results in gangrene in fingers and nose

Agents of Bioterror

Direct examination and culture Plump gram-negative rods Bipolar staining

• Safety pin appearance

Agents of Bioterror

Francisella tularensis BSL-3 pathogen Zoonotic disease Infectious dose

• As low as 10 organisms

Ulceroglandular tularemia Skin infection

• Bite of infected insect • Handling infectious materials

Cutaneous Lesions

Agents of Bioterror

Clinical manifestations Symptoms

• Fever with chills • Headaches • Cough • Chest pain • Lesions at site of entry

Occasionally respiratory disease

Agents of Bioterror Brucella spp.

Small gram-negative pleomorphic aerobic coccobacilli

• Brucella melitensis • Brucella suis • Brucella abortus

Mostly eliminated in the United States • BSL-3 containment required

Transmission • Breaks in skin • Ingestion of food products • Aerosols in laboratory conditions

Agents of Bioterror (Cont’d)

Symptoms Malaise, night sweats, relapsing fever, chills,

myalgia • Requires 5-35 days of incubation before symptoms

Can persist for months Most recover without treatment

Previous use as a biologic weapon

Agents of Bioterror (Cont’d)

Burkholderia species B. mallei

• Glanders B. pseudomallei

• Melioidosis Symptoms

• Fever, myalgia, headache, and chest pain Caused by cutaneous lesions, bloodstream infections,

pneumonia

Agents of Bioterror (Cont’d)

Coxiella burnetii Causative agent of Q fever (Query fever) Reservoirs

• Cattle, sheep, goats, dogs, cats, deer, fowl, and humans • Exposure in vet or animal handlers

Transmission • Urine, milk, feces, tissues, and fluids expelled during

birth • Incubation period 2-3 weeks

Agents of Bioterror

Smallpox Two major forms

• Variola major 30% mortality in unvaccinated 3% in vaccinated

• Variola minor Similar but much less severe disease

Smallpox Pustules

Agents of Bioterror

Viral hemorrhagic fevers Ebola, Marburg, Lassa fever, Crimean-Congo, Rift

Valley fever, Hantavirus Transmission

Direct contact Urine, semen

Agents of Bioterror (Cont’d)

Clinical manifestations Incubation period 2 to 3 weeks Fever, rash, myalgia, arthralgia, nausea,

conjunctivitis, diarrhea, and CNS symptoms Bleeding, DIC, hemorrhage of mucous

membranes • Some have high mortality rates

Agents of Bioterror

Toxins Clostridium botulinum toxin Staphylococcal enterotoxins Ricin

• Contamination of food or water sources