Listeria Monocytogenes Infections
Basmah almaarik
#Lab 7
Listeria monocytogenes
is the only species
that infect humans.
Infection most common in:
Pregnant women
still birth
Fetuses
Newborns
Immunocompromised individuals.
Specimen received:
CSF.
Blood.
Gram Positive Bacilli Pleomorphic rods
(coccobacilli = short bacilli) can form chains.
Non-capsulated
Aerobic and
facultative
anaerobe.
Grow on Nutrient
Agar: very light
growth & give
bluish coloration
reflect blue
light.
Nutrient Agar
On BA: small
translucent drop-like
colonies (moist) with
small zone of slight
beta-hemaolysis
Can grow at
refrigeration
temperature (4
˚C)
Temperature
range for growth
is 3 – 45 ˚C; with
an optimum of
30 ˚C.
24 h.
Listeria.
Catalase +ve.
CAMP +ve.
Group B
Streptococcus.
Catalase –ve.
CAMP +ve (GBS)
Listeria.
Catalase +ve.
Esculin Hydrolysis
+ve
Group D Streptococcus
Catalase -ve.
Esculin hydrolysis +ve
(GDS)
Listeria
Short gram positive
rods, can occur as
diplobacilli or in
short chain.
Catalase +ve.
Motile at room
temperature
25
ºC
Corynebacterium spp.
Polymorphic gram
positive rods.
Catalase +ve.
Non motile at any
temperature
Semisolid medium showing the typical
"umbrella" growth.
Negative control
non-motile
Positive
umbrella like
motility at
Room
Temperature
Wet preparation examined under microscope
X40.
Slide + drop of saline
examine under X40
Listeria monocytogenes
Distinctive tumbling motility in
a liquid medium
@
25 ºC
1.
Gram stain (short gram positive rods)
2.
Catalase +ve.
3.
Slight beta-hemolysis on blood agar.
4.
Umbrella like motility on semi-sold media
(soft agar) at room temperature.
•
Keep your refrigerator clean and cold—below
40° F.
•
Refrigerate or freeze food within two hours.
•
Thoroughly cook meat and poultry.
If you just can’t resist the idea of a
pastrami and Swiss, be sure to heat the meat
until steaming to kill bacteria.
•
Separate uncooked meats from other foods.
•
Eat only pasteurized dairy products.
•
Avoid soft cheeses like feta .
•
Don't eat refrigerated meat or seafood spreads,
and smoked seafood
For Pregnant women and
others at higher risk for
Listeriosis
:
1.
Perform Gram Stain.
2.
Perform Catalase.
3.
Inoculate organism in soft agar to see
Umbrella like motility.
For demonstration:
1.
See Listeria on blood agar.
2.
See listeria on Nutrient agar.
3.
See umbrella like motility in a soft agar.
4.
See gram stain of Listeria.
Listeria monocytogenes is a bacterium that infects humans, especially pregnant women, newborns, and immunocompromised individuals. It can be differentiated from other bacteria based on its morphology, culture characteristics, and biochemical tests. This summary covers important aspects such as its growth conditions, differentiation from other streptococci, and motility characteristics.
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Presentation Transcript
LISTERIA MONOCYTOGENES Basmah almaarik #Lab 7
LISTERIA SPP. Listeria monocytogenes is the only species that infect humans. Infection most common in: Pregnant women still birth Fetuses Newborns Immunocompromised individuals. Specimen received: CSF. Blood.
LISTERIA MONOCYTOGENES MORPHOLOGY Gram Positive Bacilli Pleomorphic rods (coccobacilli = short bacilli) can form chains. Non-capsulated
CULTURE OF LISTERIA Aerobic and facultative anaerobe. Grow on Nutrient Agar: very light growth & give bluish coloration reflect blue light. Nutrient Agar
CULTURE OF LISTERIA On BA: small translucent drop-like colonies (moist) with small zone of slight beta-hemaolysis
CULTURE OF LISTERIA Can grow at refrigeration temperature (4 C) Temperature range for growth is 3 45 C; with an optimum of 30 C. 24 h.
HOW TO DIFFERENTIATE BETWEEN GROUP B STREPTOCOCCUS AND LISTERIA? Listeria. Catalase +ve. Group B Streptococcus. Catalase ve. CAMP +ve. CAMP +ve (GBS)
HOW TO DIFFERENTIATE BETWEEN GROUP D STREPTOCOCCUS AND LISTERIA Listeria. Group D Streptococcus Catalase +ve. Catalase -ve. Esculin Hydrolysis +ve Esculin hydrolysis +ve (GDS)
HOW TO DIFFERENTIATE BETWEEN CORYNEBACTERIUM AND LISTERIA? Listeria Corynebacterium spp. Polymorphic gram positive rods. Short gram positive rods, can occur as diplobacilli or in short chain. Catalase +ve. Catalase +ve. Motile at room temperature 25 C Non motile at any temperature
MOTILITY OF LISTERIA MONOCYTOGENES Semisolid medium showing the typical "umbrella" growth. Positive umbrella like motility at Room Temperature Negative control non-motile
MOTILITY TESTING USING WET PREPARATION Wet preparation examined under microscope X40. Slide + drop of saline examine under X40 Listeria monocytogenes a liquid medium @ 25 C Distinctive tumbling motility in
SUMMARY OF LISTERIA IDENTIFICATION USED IN THE LABORATORY 1. Gram stain (short gram positive rods) 2. Catalase +ve. 3. Slight beta-hemolysis on blood agar. 4. Umbrella like motility on semi-sold media (soft agar) at room temperature.
For Pregnant women and others at higher risk for Listeriosis: Keep your refrigerator clean and cold below 40 F. Refrigerate or freeze food within two hours. Thoroughly cook meat and poultry. If you just can t resist the idea of a pastrami and Swiss, be sure to heat the meat until steaming to kill bacteria. Separate uncooked meats from other foods. Eat only pasteurized dairy products. Avoid soft cheeses like feta . Don't eat refrigerated meat or seafood spreads, and smoked seafood
YOUR WORK FOR TODAY: 1. Perform Gram Stain. 2. Perform Catalase. 3. Inoculate organism in soft agar to see Umbrella like motility. FORDEMONSTRATION: 1. See Listeria on blood agar. 2. See listeria on Nutrient agar. 3. See umbrella like motility in a soft agar. 4. See gram stain of Listeria.
