Gram – Negative Zoonotic Rods Flashcards
4 medically important genera:
Brucella
Pasteurella
Francisella
Yersinia
Reservoir: cows
B. abortus
Reservoir: goats
B. melitensis
Reservoir: goats
B. melitensis
Reservoir: pigs
B. suis
Reservoir: dog
B. canis
Virulence Factors of Brucella spp.
- Capsule
- Tropism to erythritol
Transmission:
- Direct contact with contaminated livestock or aborted placentas.
- Ingestion of infected milk.
- Inhalation of organisms.
Brucella spp.
- Diurnal fever – “Undulant fever”
- Non – specific signs and symptoms
- weakness - sweats
- anorexia - malaise - Organomegaly – splenomegaly, hepatomegaly and lymphadenopathy
Brucellosis/ Bang’s Disease
Induces abortion in animals
Brucella spp.
Rod to coccoid –shaped, arranged singly or in pairs –“appearance
of a sand”
Brucella spp.
- slow growing
- growth enhanced by 5 to 10 % CO2
Brucella spp.
Culture for Brucella spp.
i. Blood Agar Plate (BAP) – incubate for 4- 6weeks
ii. MacConkey Agar
iii. Brucella Agar
• Facultative anaerobe
• Non – motile
• Range morphologically from coccobacilli to long filamentous rods
• Found as commensals in the upper respiratory tract of fowl and mammals
Pasteurella spp.
most important human pathogen of Pasteurella spp.
Pasteurella multocida
Virulence factor of Pasteurella multocida
Capsule
Transmission of Pasteurella multocida
From dog or cat bites
gram – negative short rod with bipolar staining
Pasteurella multocida
Culture:
- rarely grown on gram – negative differential media (EMB or MacConkey)
- grow on Blood Agar (BAP) may have musty or mousy odor
Pasteurella multocida
Biochemical tests of Pasteurella multocida
Catalase = +
Indole = +
Oxidase = +
ONPG – Negative
Penicillin susceptible
Biochemical tests for Pasteurella multocida
Catalase = +
Indole = +
Oxidase = +
ONPG – Negative
Penicillin susceptible
Reservoir:
- Cottontail rabbit – primary reservoir
- both wild and domesticated animals
- birds
- arthropods
- also in water, muds, and animal feces
Francisella tularensis
Transmission:
1. Tick bites
2. Inhalation
3. Ingestion
4. Direct contact with infected animals
Francisella tularensis
Clinical manifestations:
Causes Tularemia
Ulceroglandular – at the site of inoculation
Francisella tularensis
