Francisella Flashcards
What family does Genus Francisella belong to?
Family Francisellaceae (Gammaproteobacteria)
What are the three important Francisella species?
F. tularensis F. philomiragia F. noatunensis
Francisella Gram _____? Shape?
Gram Negative, small, pleomorphic
Francisella Motile/Non-motile?
Non-motile
Francisella Oxidase Pos/Neg?
Oxidase negative
Francisella Catalase Pos/Neg?
Weakly catalase positive
Francisella Aerobe/Non-aerobe?
Obligatory aerobic
Francisella Spore/Non-spore forming?
Do NOT produce spores
Francisella Is this a fastidious organism? (requires special nutrition to grow)
EXTREMELY FASTIDIOUS!! Glucose-Cysteine blood agar necessary
Francisella tularensis
Highly infectious Causes Tularemia REPORTABLE Affects very wide range of species Several different subspecies
What are common names for Tularemia?
Rabbit Fever Deer-fly fever Lemming Fever
What is the disease also known as Rabbit Fever, Deer-fly fever and Lemming fever?
Tularemia, caused by F. tularensis
F. noatunensis
Emergent aquatic animal pathogen
Francisella tularensis Pathogenicity and geographical distribution
Most important human pathogens: F. tularensis subsp. tularensis. North America. TYPE A F. tularensis subsp. holarctica. Europe. TYPE B
F tularensis subsp. tularensis
Potential Bioweapon! Extreme virulence Low infectious dose Easy aerosol dissemination Severe illness and death 10 CFUs inhaled can cause disease 30-60% untreated infections can be fatal
Francisella Virulence factors
Capsule - Mannose Cell wall - LPS Acp - Acid phosphatase Pathogenicity Island
What does Mannose on a capsule do?
Mannose receptors in phagocytes Want to be phagocytized by naive-macrophages
Francisella Role of Acp
Acid phosphatase Suppresses respiratory burst of phagocytes
Francisella Pathogenicity Island Name the components
igl (Intracellular growth locus) Mgl (Macrophage growth locus) Pdp (Pathogenicity determinant proteins)
Francisella Products of igl
Intracellular survival in phagocytes T6SS Iron uptake
Francisella Mgl role
Many functions Regulatory of igl
Francisella Pdp role
Pathogenicity determinant proteins Intracellular survival in phagocytes Virulence
Francisella Reservoir
Infected lagomorphs, rodents, amoebae
Francisella Transmission
Mainly by *ticks*, mosquitos, deer fly Water Prey Humans- percutaneous, conjunctival, inhalation, ingestion
Which tick species transmit Francisella?
Dermacentor variabilis Dermacentor andersoni Amblyomma americanum
Name the six forms of Tularemia
**Depends on mode of transmission** *Ulceroglandular* from arthropod vector Oculoglandular Pneumonic Oropharyngeal Gastrointestinal Typhoidal
Tularemia presentation in different species
Wide variety of presentations in humans Cats**Most frequent domestic animal Sheep/Horse/Young pigs Dogs fairly resistant
Name/describe this lesion
Ulcer caused by Francisella tularensis on the hand “Ulceroglandular”
Name/describe this lesion
Oculoglandular tularemia in human
Ulceroglandular tularemia
80% of cases Often from tick bite
Pulmonary & Oropharyngeal/Gastrointestinal tularemia
Acquired via inhalation Oral exposure - Water or meat Most dangerous of all (40-60% case fatality)
Clinical signs of Tularemia in humans
Depends on mode of infection High fever, headache, signs of toxicity (myalgia, anorexia, prostration) for several days Pneumonia with non-productive cough Liver damage- elevated liver transaminases
Francisella Pathogenesis
Infectious event–> Local phagocyte population, uptake, survival and multiplication, survive complement & colonize regional lymph nodes–> Granulomatous inflammation (intracell survival, Mgl, igl, T6SS, apoptosis & necrosis of phagocytes & infection of other cells
Francisella Pathology
Irregular microabscesses Pyogranulomatous inflammation (liver, spleen, lymph nodes, necrotizing pneumonia) Highly cytotoxic (damage to inflammatory & parenchymal cells) Local lesions - walled granulomatous structures with central necrosis - Often suggestive of necrosis
Francisella Case Report
Non-human primates in a zoo
Francisella Case Report
Prairie dog in Texas - Francisellosis
Francisella Pathogenesis
Intracellular survival*** Evade phagocytes Macrophage=primary target Eventual host cell death, moves on to neighboring cells
Francisella Immunological aspects
Largely Cell Mediated Immunity Live attenuated vaccines for at-risk populations
Francisella Lab diagnosis Stain used for Francisella
Giemsa stain exudates
Francisella Lab diagnosis Serology tests used
IFA ELISA Agglutination
Francisella Lab diagnosis Culture: Agar used
Glucose-cysteine heart agar Chocolate agar Oxidase Negative Does not grow on MacConkey
Francisella Lab diagnosis - all tests used
Giemsa stains Serology Culture In vivo infections Molecular - PCR
Francisella Name the agar types
A- Buffered charcoal yeast extract B-Chocolate agar medium C-Sheep’s blood agar D-Cysteine heart agar
Francisella Treatment & Control
Antimicrobials Control Ticks Limit access to water/feed Wildlife population control
Francisella Antimicrobial treatment
Facultative intracellular organism Aminoglycosides - Gentamycin & Streptomycin Fluoroquinolones Tetracyclines
Francisella Type of aquatic organisms
Warm & Cold water Marine & Fresh water Wild & Cultured fish **Tilapia, cod, hybrid striped bass & others***
Francisella Describe disease lesions in aquatics
Granulomatous lesions in spleen & head kidney (hematopoetic)
What fish cells do Francisella spp. survive in?
Fish macrophages & monocytes
What bacteria caused these lesions?
Francisellosis in fish
What bacteria caused these lesions?
Francisellosis in fish
What conditions should Francisella be cultured at?
In vitro temperature growth: 20-30C, NO GROWTH at 15 or 37C
