Unit 3: Acinetobacter, Francisella, Coxiella, Legionella, and Heliobacter Flashcards
What type of bacteria are Acinetobacter?
opportunists
What species of Acinetobacter is accounts for most of the human infections by this genus?
Acinetobacter baumannii
On gram stain, what does the genus Acinetobacter look like?
gram negative rod - may pair or chain
What do colonies of Acinetobacter look like?
may be large and mucoid or small and non-pigmented
Is the genus Acinetobacter oxidase negative or positive?
negative
In regards to oxygen, what type of organims are in the Acinetobacter genus?
obligate aerobes
What is the natural habitat of Acinetobacter?
widespread in soil, water, sewage and feces - colonize the skin
What diseases are associated with Acinetobacter infection?
nosocomial infections mainly in immunocompromised patients and occasionally urinary tract infections in animals
What is the cause of rabbit fever?
Francisella tularensis
What are the different biovars of Francisella tularensis?
tularensis, palaearctica, novicida
Where is Francisella tularensis biovar tularensis found?
only in North America
Where is Francisella tularensis biovar palaeartica primarily reported?
in Russia and Scandinavian countries - it is known as the beaver strain
What species does Francisella tularensis biovar novicida infect?
humans
What is the morphology of Francisella tularensis?
gram negative, short, very small, non-motile, non-encapsulated rods - may be pleomorphic
What is required for growth of Francisella tularensis and how long does it take?
it requires cysteine - growth in minute colonies - facultative anaerobe but grows aerobically
2-10 days
What is the natural habitat of Francisella tularensis?
ticks, wild rodents, and rabbits act asreservoirs of biovar tularensis. Water rodents and beavers act as reservoirs of biovar palaearctica
How is Francisella tularensis spread?
by contact with infected rabbits or rodents and via infected ticks
How does Francisella tularensis gain entry?
through skin abrasion, conjunctivae, ingestion, and aerosol
Is the infectious dose of Francisella tularensis high or low?
low
What lesions are associated with infection of Francisella tularensis in rabbits?
small, necrotic, granulomatous foci in the liver, spleen, and lymph nodes
What are the types of Francisella tularensis infection in humans?
pneumonic form and typhoidal form
How do humans get the pneumonic form of Francisella tularensis?
by inhaling it
How do humans get the typhoidal form of Francisella tularensis?
by ingesting it
What lesions are associated with the human form of Francisella tularensis infection?
granulomatous nodules that ulcerate
What immunity is involved with Francisella tularensis infection?
Cell mediated immunity
How do you treat for a Francisella tularensis infection?
Streptomycin and gentamicin
How do you diagnose for a Francisella tularensis infection?
PCR on blood, pulmonary washings, and tissues
What does Coxiella burnetii look like on gram stain?
small, pleomorphic, gram-negative bacterium
What type of bacteria is Coxiella burnetii?
an obligate intracellular bacterium
What does Coxiella burnetti cause?
Q-fever in humans.
Abortions and respiratory tract infections in ruminants
Coxiella burnetti has two distinct phases that are morphologically identical. What are they and how infective are they?
Phase 1 - highly infectious
Phase 2 - less infectious
Coxiella burnetti infects a wide variety of animals and is currently thought to be a problem in mainly _____, ______, and ______.
cattle, sheep, goats
How do humans get infected with Coxiella burnetti?
they consume contaminated animal products
How do you treat a Coxiella burnetti infection?
tetracycline
Surgery may be needed in humans with chronic valvular endocarditis
How do you prevent Coxiella burnetti infection?
In Europe there is an inactivated Phase I product for immunization of ruminants.
An inactivated product is available in Australia for high-risk humans
What is Coxiella burnetii shed in?
urine, milk, feces, and the placenta
What can spread Coxiella burnetti?
ticks
What clinical signs are associated with acute Q fever?
fever followed by myalgia, headache, sweating
rarely fatal
When does chronic Q fever present?
may start 2-20 years after infection
What is the main complication associated with the chronic form of Q fever?
chronic vegetative valvular endocarditis
What other disease processes can occur as a result of Coxiella burnetii?
chronic hepatitis and glomerularnephritis
_______ ________ accounts for 90% of the respiratory infections in humans from this genus.
Legionella pneumophila - Legionaire’s disease
70% if the respiratory cases assoicated with Legionella pneumophila are due to what serotype?
one
What causes Pontiac fever (acute flu like illness)?
L. lingbeachae, L. feeleii, L. micdadei, and L. anisa
What is Helicobacter pylori associated with?
acute gastritis and gastric and duodenal ulcers in humans
Where has Helicobacter heilmannii been isolated from?
the gastric mucosa of humans, cats, dogs, and pigs - in associated with gastric diseases
What is Helicobacter mustelae associated with?
gastric ulcers in ferrets
On gram stain, what does the genus Helicobacter look like?
gram-negative U shaped, rods, or rounded form with polar flagella
In regards to oxygen, what organisms are in the Helicobacter genus?
microaerophilic
How is Helicobacter pylori transferred?
through food and mouth to mouth especially in areas with poor sanitation
What is the pathogenesis of Helicobacter pylori infections?
They invade between cells of the gastric mycosa and can be found in many sites including within enterocytes. The urease enzyme generates ammonium ions and CO2 that are responsible for much of the tissue damage. The organism uses the ammonium ions to counterbalance the highly acidic pH of the stomach.
What specific disease is associated with Helicobacter pylori?
peptic ulcer disease
How are Helicobacter infections diagnosed?
invasive diagnostic tests for urease, histology, culture, and PCR.
Stool antigen tests, serologic tests, and carbon labelled urea breath tests work as well
What is responsible for recurrent Helicobacter disease?
residual organisms in the tissues
What is NDM1?
New Dehli metallo-beta lactamase - a resistant strain of Acinetobacter that is resistant to all beta lactams and most other antimicrobials
