20 – Francisella and Brucella Flashcards
Microbial characteristics
- Small gram-negative cocco-bacilli
- Biocontainment level 3
- All are intracellular parasites
- Found in a wide variety of animal species
Francisella microbial characteristics
- Obligate aerobe
Brucella microbial characteristics
- Aerobic, capnophilic
- Composed to 2 chromosomes
- Stained with modified Ziehl-Neelson stain=BRIGHT RED COCCO-BACILLI IN CLUSTERS
Francisella tularensis: natural host or habitat
- Found in primarily northern countries
- ONE FOUND IN RODENTS
o NA principal reservoir=cottontail rabbit, wild hares and beavers/squirrels
o But also other species
Brucella spp. natural host or habitat
- Host associated
- Syria has highest incidence globally
- Guatemala and Costa Rica highest in Americas
Francisella tularensis: virulence factors
- Mystery
- Intracellular pathogen: macrophages, escapes phagosome then replicates in cytosol
- Encapsulated
- No IDed exotoxins
Brucella spp. virulence factors
- Lack classical VFs
- Doesn’t have genes associated with HORTIZONTAL gene transfer
- LPS O-chain
- Cyclic beta-1,2 glucan: prevents fusion with lysosomes
- VirB and type IV secretions systems: prevents lysosome function
Francisella tularensis: Tularemia
- very low infectious disease
- endosymbionts of ticks!
- *incubation period ~48hr following oral exposure
Tularemia is spread by
- ticks (dermacentors, and A. Americanum) and deer flies
o vertical transmission occurs in ticks - direct contact with infected animal
- ingestion of contaminated water
Tularemia infected dogs and cats can be treated with antimicrobials
- Streptomycin=treatment of choice in people
- Use of similar drugs likely useful in companion animals
Tularemia susceptibility varies
- Cattle, pigs, and goats seem LEAST susceptible
- CATS ARE QUITE SUSCEPTIBLE
Tularemia in dogs
- Anorexia, low grade fever
- Ocular signs (uveitis and conjunctivitis)
- Sudden death reported following sniffing a dead infected rabbit
Tularemia in cats
- Fever, depression, lymphadenopathy, splenomegaly
- Oral or lingual ulceration (ingestion of infected rabbit)
- Abscessation
Tularemia in people: incubation period
- 2 days to 3 weeks
Tularemia in people: form of disease depends on route of infection
- Ulceroglandular tularemia=most common
- Glandular tularemia=next most common
Tularemia in people: ulceroglandular tularemia
- Ulcerated skin lesions at site of inoculation (bite or scratch)
- Acute onset fever, chills, headache, sore through and sometimes diarrhea
- Lymph nodes may SUPPURATE and require drainage
Tularemia in people: glandular tularemia
- Lymphadenopathy w/o obvious skin lesions
- Lymph nodes may SUPPURATE and require drainage
Which people are at greatest risk of Tularemia?
- Hunters
- Large animals vets and farmers
- *only about 5 per year
What has pneumonic tularemia in people been associated with?
- Gardening/landscaping work
- *don’t run over dead animals with lawn mower=may aerosolize something nasty
B. abortus in cattle
- NOT in Canada
- Still present in BISON
- *disease are of the reproductive system
B. abortus in cattle: disease are of the reproductive system
- Affinity for ruminant placenta: abortions
- In bulls: orchitis and epididymitis
- May see synovitis (hygromas)
When is transmission of B. abortus in cattle the highest?
- After parturition
How does infection of B. abortus in cattle occur?
- Ingestion
- Penetration of skin or intact conjunctiva
- Semen from infected bulls used in AI
What is a risk of getting B. abortus in cattle?
- Grazing on contaminated pastures
o Can survive 1-3 months in environment
Treatment of B. abortus in cattle
- Canada: call CFIA=stamp out
- Elsewhere: difficult to treat as it is intracellular
B. melitensis in goats and sheeps
- Never reported in Canada
- Primarily in Mediterranean region
What is the most obvious sign of B. melitensis in goats and sheep?
- Abortion in late pregnancy
o Organism ‘hides out’ in lymph nodes associated with mammary glands
o Can shed in milk for years=WHY WE PASTEURIZE
Transmission of B. melitensis in goats and sheeps through contact with
- Placenta
- Milk
- Vaginal discharge
B. melitensis in people
- “malta Fever”
o The guy realized it was coming from goats milk
Treatment of B. melitensis in goats and sheep
- In Canada=call CFIA-stamp out
Control of B. melitensis in goats and sheep
- Hygiene: clean up after lambing/kidding
- Vaccination: prevent infections when exposed
Why a drop in Brucella spp. in humans?
- ILLEGAL TO SELL UNPASTEURIZED MILKE
- Now only 5-15 cases
B. suis in pigs
- Never reported in Canada
- Reproductive disease
- Similar clinical signs can be caused by B. abortus or B. melitensis
B suis in pigs is a reproductive disease: sows
- Infertility
- Abortions
- Possibly fetal mummifications
B. suis in pigs is a reproductive disease: boars
- Orchitis
- Swelling and necrosis of testicles
- Lameness
- Arthritis
- Discospondylitis
How does transmission of B. suis in pigs occur?
- Introduction of infected animals into the herd
- AI contaminated semen
- *wildlife can maintain the organisms (rats and hare)
How does CFIA work to keep Canada domestic herd Brucella free?
- Import controls
- Surveillance
- Investigate suspect cases
- Depopulation
- Decontaminate
- Post-stocking testing
What are the 2 possible reservoirs in Canada for Brucella?
- B. abortus in bison (Wood Buffalo National Park)
- Rangiferine brucellosis (B. suis) in arctic caribou
B. canis in dogs
- Is in Canada
- Increasingly seen due to importation of rescue dogs
B. canis in dogs: presentations
- Bitches abort dead fetuses
o Suspect if occurs 2 weeks before term - *uncastrated males are more commonly IDed
o Present with HUGE testicles
o Not usually painful
o Secondary dermatitis form licking - Osteomyelitis and discospondylitis also occur
- Uveitis and ocular disease in chronic infections
B. canis in dogs: transmission
- Shed ruing estrus
- High numbers of organisms in aborted pups
- Seminal fluid and urine from infected males
o *intermittent shedding reported for up to 2 years
B. canis in dogs: treatment
- Intracellular organism=tricky
- No treatment is 100%
o Multiple antimicrobial regimens - Males=neutered and given antimicrobials
- DO NOT ASSUME CURE
- *do NOT breed positive animals
B. inopinata in frogs
- Recently recognized species
- Excoriations and granulomatous inflammation was seen in thighs and abdomen
Sample collection
- Handled with CAUTION
o Double gloving
o Respiratory protection
o Re-capping needles=ABSOLUTE NO-NO
Francisella sample collection
- Swab ulcers or wounds
- Store in Aimes media with charcoal
- Send tissues to lab for freezing
- Blood for serology
Brucella spp sample collection
- Abortion: whole fetus
- Orchitis: ejaculate, tissues
- Lymph nodes
- Milk
- Aspirates, swaps
Lab ID
- Make sure to tell the lab=HIGH RISK
Lab ID: Francisella
- Culture
- Cytological evaluation of smears from lesions
- Immunohistochemistry of formalin fixed tissues
- Serology
- PCR
- *patient history important to select for tests
Lab ID: Brucella
- Serological tests (most common)
- Culture (gold standard)
- PCR
- variety of agglutination tests
- *there are FALSE reactors due to cross-reactivity of antibodies to other organisms (ex. Yersinia entercolitica)
Brucella infections in people can be challenging to diagnose
- Long incubation period (1 week to 3 months)
- Wide spectrum of presentations: often chronic, non-specific disease
- Foci of infection and suppuration in joints or viscera
Wide spectrum of presentations of Brucella infections in people
- Fevers, chills, malaise, severe headache
- Cutaneous/vascular diseases; marcopapular rashes or deep vascular thrombosis
- *undulant fever is a classical sign
Undulant fever is a classical sign of Brucella infections in people
- Waxing and waning fever
o 2-3 weeks of fever at night
o Followed by period of normothermia and feeling good
o Cycle repeats
Zoonotic/interspecies transmission
- Estimated 500,000 cases/year
- *most commonly associated with unpasteurized dairy products (B. melitensis and abortus)
- *beware when travelling
o Dairy products and undercooked meat
B. canis: zoonotic
- Lower risk of transmission compared to B. abortus, meletensis or suis
- At risk= vets in contact with abortuses and lab workers
What is the most common Lab acquired infection?
- Brucella
What can B. abortus, melitensis and suis have the potential for? (bad)
- Biological weapons
Brucella can be successfully treated
- Prolonged antimicrobial therapy
- Oral tetracycline for 6 weeks, followed by daily IM injections of streptomycin for 2-3 weeks
