Gram- Positive Bacilli Flashcards
It is both a human and animal pathogen
It is aerobic or facultatively anaerobic and non-spore formin
Listeria monocytogenes
It is motile with pretrichous flagella and exhibits a characteristic ―tumbling motility
Listeria monocytogenes
It can grow in a high salt medium with up to 10% NaCl
Listeria monocytogenes
It is recovered from the soil, dust, water, dairy products, and processed meats
It causes miscarriage or stillbirth in humans
Listeria monocytogenes
Virulence factors of Listeria monocytogenes
Listeriolysin O, catalase, supeoxide dismutase, phospholipase C, and p60
Mode of acquisition of Listeria monocytogenes
Ingestion of contaminated food such as meat, chicken, dairy products, and
vegetables
Microscopy: Coccobacillary in form and are arranged singly or in short chains that resemble
streptococci
Listeria monocytogenes
Culture: BAP-colonies are small, smooth, transluscent, grayish blue, and are surrounded by a
narrow zone of Beta hemolysis
Listeria monocytogenes
It is a serious infection that affects neonates, pregnant women, and immunocompromised hosts
Processed meat products should be thoroughly cooked or heated before consumption as a
primary preventive measure
Listeriosis
are the most important host defense against Listeriosis
Macrophages and T-lymphocytes
It usually occurs during the third trimester of pregnancy
It leads to miscarriage or stillbirth
Signs and symptom: Flu-like illness, fever, headache, and myalgia
Maternal disease (Pregnancy)
It is associated with an intrauterine infection due to the aspiration of infected amniotic
fluid
The infected infants are at full term and appear healthy at birth
It leads to meningitis that is usually seen by the third week of life
Neonatal disease
It develops though the ingestion of contaminated dairy products and processed meat
products
. Disease of immunocompromised host
SIM test: Has an ―”umbrella-shaped” or inverted Christmas tree‖ pattern at room
temperature at 25C but not at 35C
Listeria monocytogenes
Biochemical test for Listeria monocytogenes
(+) Glucose fermentation
(+) Catalase and motility
(+) CAMP reaction-―block type‖ hemolysis
(+) Hippurate and bile esculin hydrolysis
(+) growth in 6.5% NaCl
(+) Voges-Proskauer and Methyl red tests
(-) H2S production, nitrate reduction, and urease
Gram positive bacilli, the only catalase-negative, non-spore-forming, Gram-positive, rod-shaped bacterium that
produces hydrogen sulfide.
Erysipelothrix rhusiopathiae
It is isolated from wild and domestic animals like birds and fish
Erysipelothrix rhusiopathiae
Major: reservoir of Erysipelothrix rhusiopathiae
Domestic swine
Gelatin stab culture: Has a pattern of a ―”pipe cleaner” or a ―”test tube brush” at 22C
Erysipelothrix rhusiopathiae
Mode of transmission: Direct contact with infected excreta, blood, and flesh of animals through
skin breaks
Erysipelothrix rhusiopathiae
Predisposed individuals: Veterinarians and fish handlers
Erysipelothrix rhusiopathiae
Culture: BAP- Colonies are pinpoint with alpha-hemolytic zone
Erysipelothrix rhusiopathiae
Best specimens for Erysipelothrix rhusiopathiae
Tissue biopsies or aspirates from skin lesion
the best site for collecting specimens of Erysipelothrix rhusiopathiae
the outward margin of the lesion
a. Large and rough colonies-curled, slender, filamentous with a tendency to overdecolorize and become Gram-negative bacilli
b. Small and smooth colonies-transparent, glistening, and slender rods
E.rhusio
Culture: BAP- Colonies are pinpoint with alpha-hemolytic zone
The organism can grow on BAP and CAP for up to seven days
Erysipelothrix rhusiopathiae
curled, slender, filamentous with a tendency to overdecolorize and become Gram-negative bacilli
Large and rough colonies
transparent, glistening, and slender rods
b. Small and smooth colonies-
(+) H2S production in a TSI medium
(+) Glucose and lactose fermentation
(-) Catalase, oxidase, esculin hydrolysis, nitrate reduction, VP, and urease
Erysipelothrix rhusiopathiae