Agents of Bioterror

Question 1

Define bioterrorism

Answer 1

Intentional use of security sensitive biological agents to produce disease/death in animals/humans/plants.

Question 2

Genetic warfare may be an emerging threat in bioterrorism, list 3 concerns of genetic warfare

Answer 2

Genetic warfare may: render a vaccine ineffective, confer resistance to therapeutically useful antimicrobials, enhance virulence of a organism

Question 3

You have cultured a gram positive bacilli on SBA that is non-haemolytic. It is catalase and oxidase positive and non-motile. What SSBA is it? What can you do to confirm that this in fact the organism you think it is?

Answer 3

Bacillus anthracis. You can confirm by finding if its mannitol negative as well as lecithinase positive on egg yolk agar by refering it to the national microbiology lab.

Question 4

Culture of suspected Bacillus anthracis needs to be confirmed by the national reference lab. How does the reference lab confirm that it is B anthracis?

Answer 4

PCR assays directed against virulence factors made by the bacteria. Virulence factors are encoded on plasmids, they include:
pX01: toxin genes responsible for gene destruction and bleeding
pX02: genes encoding poly-D-glutamic capsule which protects the cell from phagocytosis. The polyD capsule is very different from other capsules.

Question 5

How is anthrax transmitted and what are the 3 human forms of anthrax?

Answer 5

Anthrax is found as spores in soil and herbivores such as cows may ingest them and re-inoculate the soil. There is no person to person transmission of anthrax. The 3 types of human anthrax are: cutaneous, gastrointestinal and pulmonary (inhalation)

Question 6

What are the specimens of choice from people with cutaneous and gastrointestinal anthrax?

Answer 6

Cutaneous: vesicle fluid, blood or biopsy
GI: blood, NOT STOOL

Question 7

What form of human anthrax is the most likely presentation of bioterrorism? Describe the disease caused, specimens for culture/testing and treatment prevention options

Answer 7

Pulmonary anthrax. Initial symptoms include fever, cough and malaise which rapidly progresses (1-2 days) to much more serious complications with a very high mortality despite treatment. The best specimens are from sterile fluid site such as blood and biopsies of mediastinal lymph nodes. Treatments: early administration of penicillin, doxycycline and ciprofloxacin

Question 8

Describe the morphology of smallpox

Answer 8

Smallpox virus AKA variola virus is a large, dsDNA enveloped virus of the orthopoxvirus family. It sticks out on an electron micrograph because it is very big and has many envelopes.

Question 9

How is smallpox transmitted, what type of vaccine is used and what are the symptoms/prognosis of the disease?

Answer 9

Small pox is highly contagious and transmitted via contact, fomites and aerosols. The vaccine for smallpox is live vaccinia virus. Symptoms of smallpox malaise, rigors, muscle aches and fever. Small pox has a high mortality if not treated (30-50%)

Question 10

What type of exanthem occurs with smallpox and how does it progress?

Answer 10

Smallpox lesions are papules that are vesicular or pustular. They all progress at the same time unlike chicken pox (varicella zoster virus)

Question 11

How do smallpox and chickenpox rashes differ?

Answer 11

Smallpox lesions develop all at the same time, chickenpox lesion develop in succession.
Smallpox lesions predominate on the face and extremities, chickenpox lesions predominate on the face and torso.

Question 12

What is the specimen of choice for smallpox diagnosis?

Answer 12

Vesicular papule fluid

Question 13

What is the causal organism of plague, the vector, reservoir and 3 different clinical presentations of plaque?

Answer 13

Plaque is caused by Yersinia pestis. The vector for plaque is fleas and its reservoir is rodents. 
3 types of plague: 
Bubonic: infected lymph nodes
Septicemic: blood-borne
Pneumonic: most deadly

Question 14

What is bubonic plague? What type of specimens are taken?

Answer 14

Bubonic plague is characterized by sudden onset fever, malaise and myalgia and regional lymphadenitis. 80% of those who are infected become bacteremic and 60% mortality if left untreated. Specimens: from buboes or lymph node aspirates

Question 15

What is septicemic plague? What type of specimens are taken?

Answer 15

Septicemic plague is a systemic disease that is 100% fatal if not treated. Specimens: blood

Question 16

What is pneumonic plague and what makes it a possible presentation of bioterrorism? What specimens are taken?

Answer 16

Pneumonic plague is sudden presentation of normal plague symptoms including pneumonia with a rapid progression to cyanosis, respiratory collapse. It is spread from person to person by respiratory droplets. Its ability to be spread through droplets and difficult in containment make it a dangerous bioterror agent It is 100% fatal if left untreated. Specimens: sputum, BAL Treatment: doxycycline, TMP/SMX

Question 17

Describe the morphology and diagnostic characteristics of Yersinia pestis. How can it be detected?

Answer 17

Yersinia pestic is a gram negative rod of the Enterobacteriaceae family with bipolar staining and grows on MAC agar at 25 degrees. It is non-motile, urease and indole negative. It can be detected by most automated systems as well as DFA and PCR

Question 18

Describe tularemia, transmission and treatment

Answer 18

Tularemia is a plague-like illness with symptoms ranging from skin ulcers to respiratory failure. There is no person to person transmission. The reservoir is rabbits and sheep and the vector is ticks. It has a very low infective dose (1-10 bacteria). It is treated with doxycycline

Question 19

Describe the causal organism of tularemia

Answer 19

Tularemia is caused by Francisella tularensis a fastidious gram negative coccobacilli. It requires cysteine for growth: grows on Cysteine heart agar or BCYE