Small Pleomorphic Gram Negative Bacilli Flashcards
-Cottontail rabbit
– primary reservoir
- both wild and domesticated animals
- birds
- arthropods
- also in water, muds, and animal feces
Francisella tularensis
Transmission:
1. Tick bites 3. Ingestion
2. Inhalation 4. Direct
Francisella tularensis
Causes Tularemia
Ulceroglandular – at the site of inoculation
Francisella tularensis
conjunctivitis, papule of the lower lid, associated lymphadenitis
Oculoglandular Francisella tularensis
Typhoidal - Gastrointestinal
Pneumonic Tularemia
Francisella tularensis
Typhoidal - Gastrointestinal
Pneumonic Tularemia
Francisella tularensis
small pleomorphic gram – negative rods with faint bipolar staining
Francisella tularensis
-rarely done
- slow grower (usually within 2 – 4 days) - special growth requirements
i. Glucose – cyteine agar supplemented with 5% defibrinated rabbit blood
ii. Chocolate Agar with IsolVitalX
iii. Buffered charcoal yeast extract agar (BYCE)
iv. Blood agar plate (BAP)
Francisella tularensis
Colonies: blue – gray to white round, smooth and slightly mucoid
iv. Blood agar plate (BAP)
- may show small zone of alpha hemolysis
Francisella tularensis
Serologic test
– Slide agglutination or Direct fluorescent antibody test (DFAT)
- titer of 1:40 in the absence of previous disease
-Can cross react with Brucella abortus.
Francisella tularensis
Not a Facultative Intracellular parasite
Pasteurella multocida
Facul-tative anaerobe
Strictly aerobic
Non – motile
Facultative intracellular organisms
Coccoid to pleomorphic rod – shaped
Francisella spp.
Pasteurella multocida
Virulence
Capsule
Pasteurella multocida
Transmission
From dog or cat bites
Local:
wound infections – animal bites or scratch wounds
Respiratory tract infections:
Sinutsitis, peritonsillar abscess, mastoiditis, pulmonary abscess, pneumonia, empyema, bronchitis and
bronchiectasis
- systemic:
septicemia, meningitis,osteomyelitis
Pasteurella multocida
- gram – negative short rod with bipolar staining
2. Culture: - rarely grown on gram
– negative differential media (EMB or MacConkey) - grow on Blood Agar (BAP)may have musty or mousy odor
Pasteurella multocida
Pasteurella multocida
Biochemical tests:
Catalase = +
Indole = +
Oxidase = +
ONPG – Negative Penicillin susceptible
most important human pathogen
Pasteurella multocida
• 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.
Brucella spp.
Named base on their preferential host
B. abortus Cows
B. melitensis Goats
B. suis Pigs
B. canis Dog
Obligate aerobe
Facultative intracellular parasite Encapsulated, non – motile Catalase and oxidase positive
Brucella spp.
Brucella spp.
Virulence Factors
- Capsule
- Tropism to erythritol
- Direct contact with contaminated livestock or aborted placentas.
- Ingestion of infected milk.
- Inhalation of organisms.
Brucella spp.
Bang’s Disease
1. Diurnal fever – “Undulant fever”
2. Non – specific signs and symptoms
- weakness - sweats
- anorexia - malaise
3. Organomegaly – splenomegaly, hepatomegaly and lymphadenopathy
ii. Induces abortion in animals
Brucella spp.
Brucellosis/ Bang’s Disease
Gram stain
- faintly staining
- Rod to coccoid – shaped, arranged singly or in pairs –“appearance of a sand”
Brucella spp.
Culture
- slow growing
- growth enhanced by 5 to 10 % CO2
i. Blood Agar Plate (BAP) – incubate for 4- 6weeks
ii. MacConkey Agar
iii. Brucella Agar
Brucella spp.
all are catalase, oxidase and urease positive
Brucella spp.
Minimum titer of 1:160 in a standard tube agglutination test
Brucella spp.
– 4 fold or greater during the the first two months of illness
Recent brucellosis
