LECTURE - Francisella tularensis & Pasteurella multocida

Question 1

Francisella tularensis

Answer 1

• gram neg coccobacilli
• non-motile, non-spore forming
• strict aerobe
• need cysteine
• visible colonies in 2-10 days at 37 C
• caution! biosafety CDC category A

Question 2

clinical presentations of Francisella tularensis

Answer 2

• bubo = severely swollen lymph node

- ulceroglandular tularemia

Question 3

where is Francisella mainly found?

Answer 3

northern hemisphere between 30N and 71N (excluding UK)

Question 4

three main subspecies (biovars) that can infect humans (Francisella tularensis)

Answer 4

• tularensis (natural reservoir: tick or deer fly borne/rabbit associated)
• holarctica (natural reservoir: water borne/muskrat or other rodent associated)
• novicida (natural reservoir: as for F. holarctica)

** most to least severe in virulence in humans **

Question 5

different routes of infection of Francisella

Answer 5

• skin with apparent lesion = ulceroglandular (MOST COMMON)
• same as ulcero… but no skin lesion = glandular
• conjunctiva = oculoglandular
• throat lesion via water/food = pharyngeal
• inhalation of aerosol = pneumonic (MOST FATAL)
• ingestion = typhoidal

Question 6

clinical manifestations of Francisella

Answer 6

• entry: conjunctival, oral, tick or deer fly bite
• spread: systemic, lymphatic (local and mesenteric)
• disease septicemia (toxemia): abscesses, diarrhea

Question 7

francisella similar features to brucellosis but…

Answer 7

fever is continuous not remittent

and no chronic abscesses

Question 8

treatment of francisella

Answer 8

streptomycin or gentamicin - work outside of cell; but francisella is intracellular… BUT antibiotic constantly being released = minimize francisella re-infection and will eventually get rid of intracell organisms

Question 9

diagnosis of Francisella

Answer 9

• blood samples or fluid from infected organs plated on special media
• ELIA for patient Ab to Francisella antigens
• PCR

Question 10

intracellular immune subversion of Francisella

Answer 10

once inside phagosome:

• inhibit NADH oxidase, ROS, AMPs, TLR4
• live in low pH
• TLR2, 9 and 4
• escape FCP (Francisella containing phagosome) to replicate in cytosol)
• can induce host cell death
• autophagosomes

Question 11

category A

Answer 11

• easily disseminated or transmitted from person to person
• high mortality rates and potential for major public health impact
• public panic and social disruption
• special action for public health preparedness
• B. anthracis, F. tularensis, Y. pestis, Botulinum toxin

Question 12

category B

Answer 12

• easy to disseminate
• moderate morbidity rates and low mortality rates
• specific enhancements of CDC’s diagnostic capacity and enhanced disease surveillance
• Brucella sp., Salmonella, E. coli O157:H7, Staphylococcal enterotoxin B

Question 13

category C

Answer 13

• availability
• ease of production and dissemination
• potential for high morbidity and mortality rates and major health impact
• multiple drug-resistant Mycobacterium tuberculosis

Question 14

Pasteurella multocida

Answer 14

• gram neg cb
• non-motile, non-spore forming
• facultative anaerobe
• ox pos
• non hemolytic colonies visible in 1-2 days at 37 C on BAP
• five capsular types A-E
• can show bipolar (safety-pin) staining
• can cause serious disease in cattle and fowl

Question 15

most likely to spread of subspecies of P. multocida

Answer 15

P. multocida ssp. multocida

- not very highly pathogenic ; but we don’t know underlying causes of organisms that caused it to spread

Question 16

treatment of Pasteurella

Answer 16

• penicillin
• vaccines developed for animals; reduction in reservoir may reduce human exposure
• don’t let your cat or dog lick your wounds! (increasing incidences in humans)