Bartonella, Steptobacillus, Chromobacterium, Ornithobacterium & Riemerella Flashcards
What is Bartonella? Is it motile? Where is it commonly found?
aerobic, fastidious, Gram-negative coccobacillus
yes, by lophotrichous flagella
facultative intracellular bacteria found in wild and domestic animals (esp. cats)
What kind of pathogen is Bartonella? When is infection more likely?
opportunistic pathogen causing Bartonellosis
prevalent in warmer and humid regions
How is Bartonella henselae transmitted?
by cat fleas
What are the main 3 species of Bartonella causing disease?
- B. henselae —> cat flea vector; cat reservoir; human, dog, cat incidental hosts —> cat scratch disease, endocarditis, bacteremia
- B. baciliformis —> sandfly vector; human reservoir; human incidental host —> Carrion’s disease, Andean valley
- B. quintana —> body lice vector; human reservoir; humans, dog, cat incidental host —> Trench fever
What is the reservoir of Bartonella henselae? What does it tend to cause when transmitted to incidental hosts?
cats
CATS: subclinical bacteremia, feline bartonellosis
DOGS: endocarditis
HUMANS: subclinical bacteremia (from cat scratch)
How do humans become infected with Bartonella henslae from cats? What does this cause?
- fleas defecates on cat and deposits bacteria, and as the cat grooms, B. henslae accumulates on their claws
- cat scratches or bites human transmitting the bacteria
- cat scratch disease develops at the site of the scratch/bite and lymph nodes swell
How does the immune status of the host affect symptoms of cat scratch disease? What are some general symptoms?
IMMUNOCOMPETENT: local lymphadenopathy that can lead to endocarditis
IMMUNOCOMPROMISED: baciliary angiomatosis causing cutaneous lesions and lesions associated with every organ system
- fever, fatigue, loss of appetite, weight loss
How does Bartonella infection develop in cats?
- blood-sucking arthropod defecates and excretes Bartonella onto the skin surface
- Bartonella colonizes the skin and enters migratory cells
- migratory cells deposit Bartonella on the endothelium on underlying blood vessels
- Bartonella binds to RBCs, replicates, and persists within them
- blood-sucking arthropod ingests blood infected with Bartonella
What 4 virulence factors are responsible for Bartonella henslae attachment? 3 responsible for secretion/invasion?
ATTACHMENT
- multiple flagella
- bartonella adhesin A (BadA): biofilm, phagocytosis avoidance
- filamentous hemagglutinin
- Trw system: adhesion to RBC and endothelium
SECRETION/INVASION
- VirB/VirD-T4SS
- IaIAB proteins (RBC invasion)
- hemolysin
What stain is used on Bartonella for identification? What media is growth best on?
Warthin-Starry stain —> won’t Gram stain
blood-enriched media
Why isn’t serological testing recommended to diagnose Bartonella (cat scratch disease) in cats?
common false positive results
What is commonly seen on histology of Bartonella infection? Radiographs?
inflammation
pulmonary edema and cardiac enlargement in dogs
How is Bartonella infection usually treated/controlled?
- treatment not usually necessary
- antibiotics (takes 4-6 weeks): Doxycycline
- prevention of cat scratches and bites
- flea control
- wash wounds with soap and water immediately
What is Streptobacillus moniliformis? In what conditions does it typically grow?
highly pleomorphic, filamentous, Gram-negative, non-motile, facultative anaerobic bacilli (string of chains)
fastidious, microaerophilic
What are the 2 variant types of Streptobacillus moniliformis based on morphology?
- bacilary form - pathogenic, normal configuration
- L form - non-pathogenic, lack cell wall, unfavorable conditions
Where is Streptobacillus moniliformis commonly found? What is it the causative agent of?
upper respiratory tract of rodents - mice, guinea pigs, gerbils, squirrels
rate bite fever
- S. moniliformis in US
- Spirillum minus in Asia (sodoku)
What are the main 3 modes of tranmission of rat bite fever?
- rate bite or contact
- ingestion of contaminaed products by rodent urine or droppings (Haverhill fever)
- transmission from rats to cats and dogs to humans
(Streptobacillus moniliformis = zoonosis associated with rodent contact)
What are the common clinical symptoms of rat bite fever? What are some complications?
- fever
- rash
- joint and muscle pain
- headache
- vomiting
- sore throat
~ abscess
~ pneumonia
~ hepatitis
~ nephritis
~ meningitis
~ endocarditis
What agar is necessary for Streptobacillus moniliformis growth? Why?
brain-heart infusion enriched with 15% blood, 20% horse/calf serum, or 5% ascetic fluid in 5-10% CO2
it’s a very fastidious bacteria
How can the 2 morphologies of Steptobacillus moniliformis be identified on agar?
BACILIARY FORM - non-hemolytic, small, greyish colonies on blood agar
L-FORM - colonies stained by Diene’s stain with a fried-egg appearance
How does Streptobacillus moniliformis respond to catalase and oxidase tests? What is recommended to confirm diagnosis?
catalase -
oxidase -
PCR-based assay
How is Streptobacillus moniliformis treated?
- antibiotics: penicilln
- surgical drainage of large abscesses
What is Chromobacterium violaceum? What is a major unique characteristic?
Gram-negative, facultative anaerobic rod motile by polar or lateral flagella
production of the violet pigment (violacein)
Where in the environment is Chromobacterium violaceum commonly found? What kind of pathogen is it?
soil and water of subtropical and tropical regions
opportunistic pathogen of mammals that can lead to fatal systemic disease
What is the purpose of the violacein produced by Chromobacterium violaceum?
has antibiotic activity against Gram-positive bacteria, especially Staph. aureus
What are the 2 most common symptoms of Chromobacterium violaceum in humans? What can it progress into?
- skin abscesses
- septicemia
septicemia can progress into multiorgan abscesses and pneumonia
On what media do Chromobacterium violaceum grow well on? What are major characteristics of its growth?
nutrient agar, blood agar, and MacConkey agar
- produces violet pigment
- almond-like smell
- β-hemolysis
How does Chromobacterium violaceum respond to catalase and oxidase tests? What 2 treatments does it tend to be resistant to?
catalase +
oxidase +
- cephalosporins
- ampicillin
(use fluoroquinolones and aminoglycosides)
What is Ornithobacterium rhinotracheale? Where is it commonly found?
Gram-negative, non-motile, microaerophilic, pleomorphic rods
wild and domesticated species of birds
What is Ornithobacterium rhinotracheale the causative agent of? What does it cause? Is it zoonotic?
emerging poultry pathogen - Ornithobacteriosis
acute, contagious respiratory disease (pneumonia, airsacculitis) in chickens, turkeys, and older birds
NO - horizontal and vertical transmission to the same species
What are the 5 common clinical symptoms of Ornithobacteriosis?
- coughing
- reduced weight gain
- reduced egg production
- airsacculitis with accumulation of yogurt-like exudates
- pneumonia with accumulation of fibrin
How does Ornithobacterium rhinotracheale grow on blood agar and MacConkey agar? How does it respond to oxidase and catalase tests?
BLOOD: pinpoint, circular, small, gray non-hemolytic colonies
MACCONKEY: no growth
oxidase +
catalase -
What is the recommended treatment of Ornithobacteriosis?
ampicillin administered in the drinking water
What is Riemerella anatipestifer? Where is it commonly found?
non-spore forming, non-motile, Gram-negative rods
- ubiquitous in the environment
- wild and domestic birds
What is Riemerella anatipestifer the causative agent of? What is characteristic of this infection? How is it transmitted?
duck septicemia; new duck disease in domestic ducks, geese, turkeys, chickens, and other wild birds
high mortality in ducklings up to 6 weeks of age
bird-to-bird transmission through respiratory tract and skin wounds
What are 7 clinical symptoms of Riemerella anatipestifer infection?
- ocular and nasal discharge
- sneezing and coughing
- leg paddling
- head and neck tremors
- incoordination
- depression and anorexia
- greenish diarrhea
What are 4 common postmortem findings in Riemerella anatipestifer infection?
- fibrinous pericarditis*
- fibrinous perihepatitis*
- fibrinous meningitis
- fibrinous airsacculitis
On what media does Riemerella anatipestifer grow best on? What does it not grow on?
blood or chocolate agar - small, transparent, and glistening colonies (non-hemolytic)
MacConkey
How does Riemerella anatipestifer respond to catalase and oxidase tests?
catalase +
oxidase +
In what 3 ways is Riemerella anatipestifer treated/controlled?
- antibiotic therapy
- vaccination - bacterin, avirulent live vaccine
- hygiene management
Duck farm report - Infectious outbreak in a 14-21 day old flock where 2020 out of 4000 were infected, with 316 dead. Affected ducks exhibited reduced movement, ataxia, and dorsal recumbency with leg paddling. Fibrinous pericarditis, airsacculitis, perihepatitis, ventriculitis and meningitis were observed. What microorganism is likely responsible?
a. Streptobacillus moniliformis
b. Chromobacterium violaceum
c. Ornithobacterium rhinotracheale
d. Riemerella anatipestifer
D
S. moniliformis = rat bite fever
C. violaceum = mammals
O. rhinotracheale = respiratory disease
A 63 y/o male originally from Brazil and now living in a homeless shelter presents with a fever, headache, rash, and bone pain in the shins, neck, and back. On examination, lice are visible on the patient’s clothes and hospital sheets. What is the likely causative agent?
a. Bartonella henselae
b. Bartonella quintana
c. Bartonella baciliformis
d. Bartonella bovis
B, Trench fever
B. henselae = cat scratch fever (cat flea)
B. baciliformis = Carrion’s disease (sandfly)
B. bovis = cattle endocarditis (biting flies)
A 20 y/o male presented with a week history of fevers, rash, and polyarthralgia affecting his knees, elbows, and wrists. He denied any history of bites, but kisses his pet rat daily. What is likely associated with these symptoms?
a. Bartonella henselae
b. Streptobacillus moniliformis
c. Chormobacterium violaceum
d. Ornithobacterium rhinotracheale
e. Riemerella anatipestifer
B
What activity is asociated with infection of Chromobacterium violaceum?
a. inhaling cigarette smoke
b. eating raw oysters
c. drinking unpasteurized milk
d. swimming in a creek
D; environmental opportunistic pathogen
What should be associated with Bartonella henselae, Streptobacillus moniliformis, Chromobacterium violaceum, Ornithobacterium rhinotracheale, and Riemerella anatipestifer? Which are zoonotic?
cats
rats
environment
chicken
ducklings
B. henselae
S. moniliformis
