Transcript Listeria Monocytogenes

LISTERIA MONOCYTOGENES
Dr.T.V.Rao MD
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WHAT IS LISTERIOSIS
• Listeriosis, a serious infection caused by eating
food contaminated with the bacterium Listeria
Monocytogenes, has recently been recognized as
an important public health problem in the United
States. The disease affects primarily persons of
advanced age, pregnant women, new-borns, and
adults with weakened immune systems. However,
persons without these risk factors can also rarely
be affected.
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Listeria Monocytogenes is a rod-shaped aerobic and gram positive
pathogenic bacterium that invades the cytoplasm of living cells. It
develops a distinctive rocket tail structure to help push through the
cytoplasm. Eventually, these "rockets" push bacteria into neighboring
cells, propagating the infection
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LISTERIOSIS
• Listeriosis is caused by
Bacterial agent an
intracellular pathogen
Listeria Monocytogenes
• L.monocytogenes
produces infections world
wide
• Important cause of
infections in animals and
man.
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WHO ARE AT RISK WITH LISTERIOSIS
• Pregnant women
• New-borns
• People with weakened
immune systems
• People who are taking
immuno-suppressing
medication.
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LISTERIA MONOCYTOGENES
• L.monocytogenes is a Gram +
ve non spore forming.
• A specific character of the
organism manifest with
tumbling end or over end
motility at
220c – 280c but not at
370c
But makes the Microbiologists
to identify from Diptheriods,
which are mistaken and
specimens are discarded.
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CULTURE AND GROWTH
CHARACTERISTICS
• Grows on Muller Hinton
agar with sheep blood as
enrichment.
• Small zone of Hemolysis
can be observed around
and the underneath of the
colony.
• Specimens are enriched if
the tissues are kept at 40c
and plated on the media
( Cold enrichment )
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BIOCHEMICAL REACTIONS
• Bacteria are facultative
anaerobic microbes
• Catalase + motile
• Listeria produce acid
and not gas in various
sugar fermentation
tests
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CAMP POSITIVE LISTERIA
• CAMP-positive Listeria
monocytogenes inoculated at
right angles to b-hemolytic
Staphylococcus aureus. Note
the arrow-shaped zone of
weak enhanced hemolysis
indicating a positive CAMP
test. Gloves are worn when
working with
L. Monocytogenes. (Anne
Hanson, University of Maine)
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HOW HUMANS CONTACT LISTERIOSIS
• Listeria monocytogenes can be found in a variety
of dairy products, vegetables, fish and meat
products.
• Listeria monocytogenes, unlike most other harmful
bacteria, will grow slowly on foods stored in a
refrigerator.
• Listeria monocytogenes can also be spread by
contact with an infected product or surface, such
as hands or counter tops, during food preparation.
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PATHOGENESIS AND PATHOLOGY
• Listeria Monocytogenes enters through the Gastro
– intestinal tract after infections of contaminated
foods such as cheese or vegetables,
• The cell wall surface protein called Interanalin
interacts with E –CADHERIN and enters into
epithelial cells
• Bacteria produce Listeriolysin
• L.monocygenes can move from cell to with out
being exposed to
Antibodies,Complement,Polymorphonuclear cells
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WHO ARE AT HIGHER RISK
• The following conditions
may be impaired with
defective cell mediated
Immunity
Pregnancy
AIDS
Lymphomas
Organ transplant recipients
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CONTAMINATION CAUSES
LISTERIOSIS
• Listeria Monocytogenes is
found in soil and water.
• Vegetables can become
contaminated from the
soil or from manure used
as fertilizer.
• The bacterium has been
found in uncooked meats
and vegetables, soft
cheeses, deli cold-cuts, and
unpasteurized milk or
foods.
• Animals can carry the
bacterium without
appearing ill and can
contaminate foods of
animal origin such as
meats and dairy products.
• The average incubation
period is 31 days; with a
range from 11 to 47 days.
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• If acquired at birth, the
incubation period is 7 to 28
days.
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SYMPTOMS
• Fever
• Muscle ache
• GI Sx: Nausea, diarrhea
• Pregnant women: mild
flu-like Sx, miscarriage,
still birth, premature
delivery, or infected
newborn.
• If infection spreads to the
nervous system:
headache, stiff neck,
confusion, loss of balance,
or convulsions.
• Listeria can cause
Pneumonia, Meningitis,
and Sepsis.
• Lethargy
• irritability
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COMMON PRESENTING
MANIFESTATION OF LISTERIOSIS
• Vomiting;
• Nausea;
• Cramps;
• Diarrhea;
• Severe Headache;
• Constipation; or
• Persistent fever.
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LISTERIOSIS IN ADULTS
• Adults may present with
bacterimia .
Meingoencephalitis and occur
most commonly in
Immunosupressed patients in
whom Listeria is one of the
more common cause of
Meningitis
• Disease can be insidious to
fulminant
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LISTERIOSIS PRESENTING WITH
MENINGITIS
• Immunocompromised adults are at risk for a serious
infection of the blood stream and central nervous system
(brain and spinal cord). Meningitis occurs in about half of
the cases of adult Listeriosis. Symptoms of listerial
meningitis occur about four days after the flu-like
symptoms and include fever, personality change,
uncoordinated muscle movement, tremors, muscle
contractions, seizures, and slipping in and out of
consciousness.
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LATE ONSET MANIFESTATIONS
• The new born child may
present with late onset
syndrome causes the
development of Meningitis
between birth and third week
of life
• It is often caused by serotype
IV b and has a significant
mortality rate
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LISTERIOSIS AND PREGNANCY
• Pregnant women They are about 20
times more likely
than other healthy
adults to get
Listeriosis. About
one-third of
listeriosis cases
happen during
pregnancy.
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LISTERIOSIS IN NEW BORNS
• New-borns - Newborns rather than
the pregnant women
themselves suffer
the serious effects
of infection in
pregnancy.
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DIAGNOSIS
• There is no routine screening test for
susceptibility.
• Patient may present with fever, or stiff
nec, .
• A blood or spinal fluid examination (to
cultivate the bacteria) will confirm the
clinical diagnosis. .
• During pregnancy, patients need detailed
investigations to rule our Listeriosis.
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DIAGNOSIS
• Diagnosis
dependent on
isolation of
Organisms in
cultures obtained on
CSF, Blood, and
other fluids
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TREATMENT
• Listeriosis is a serious disease requiring
hospitalization.
• A combination of antibiotics is given intravenously
through a small straw-like catheter.
• When infection occurs during pregnancy, antibiotics
must be given promptly to the mother to prevent
infection of the fetus or newborn.
• The duration of antibiotic treatment is at least 2 weeks.
• Even with prompt treatment, some infections result in
death.
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ANTIBIOTIC TREATMENT
• Ampicillin
• Erythromycin
• Intravenous Trimethoprim
– Sulphmethoxazole
• Cephalosporins and Fluroquinoles are not active against
l.monocytogens
• A commination of Gentamycin and Ampicillin on clinical
basis
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FOODS TO AVOID
• Hot dogs, especially straight from
the package without further
heating. The fluid within hot dog
packages may contain more
Listeria than the hot dogs.
• Avoid spreading fluid from
packages onto other foods,
cutting boards, utensils, dishes
and food preparation surfaces.
Wash your hands after handling
hot dogs.
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KEEP YOUR FOOD SAFE –
AVOID LISTERIOSIS
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IDEAL WAY TO PREVENT LISTERIOSIS
• Completely cook all meats and eggs.
• Carefully wash raw vegetables before eating.
• Keep raw meat away from raw vegetables and prepared
foods. After cutting raw meat, wash the cutting board with
detergent before using it for vegetables.
• Avoid drinking unpasteurized milk or foods made from
such milk.
• Wash hands thoroughly after handling raw meat.
• Follow the instructions on food labels. Observe food
expiration dates and storage conditions.
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• Programme Created by Dr.T.V.Rao MD
for Medical and Health Care Workers in
the Developing World
Email
[email protected]
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• Referencec : www.slideshare.com
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