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(Listeriosis)What is Listeriosis ?

a serious infection caused by eating food contaminated with the bacteriumListeria Monocytogenes, has recently been recognized as an importantpublic health problem.

WHO ARE AT RISK WITH LISTERIOSIS ?

persons of advanced age

pregnant women

 new-borns and adults with weakened immune systems

People who are taking immune-suppressing medication

persons without these risk factors can also rarely be aected

 General characteristics

rod-shaped aerobic and motile gram positive intracellular pathogen

invades the cytoplasm of living cells

 It develops a distinctive rocket tail

push through the cytoplasm

these "rockets" push bacteria into neighboring cells, propagating theinfection

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How Hum ns cont ct Listeriosis

dairy products, vegetables, !sh and meat products.

unlike most other harmful bacteria, will grow slowly onfoods stored in a refrigerator.

spread by contact with an infected product or surface hands or counter tops

during food preparation

  athogenesis and athology

enters through the "astro # intestinal tract

cell wall surface protein called $nteranalin

interacts with % #&'%*$+ and enters intoepithelial cells

produce Listeriolysin ) membrane-damaging toin(

preads from cell to cell

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Pathogenesis

$nternalin %-cadherin

Phagocytosis 

into

epithelial

cells

Phagocytio

ssBy

 macropha

ges

and

hepatocytes

Phagolysosome

formation

(acidiccondition)

LysteriolysinO

secretion

Release from

phagolysosome

Inducing actin

polymeriation incytoplasm

!orming lopods

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 epithelial cells via the interactions of the surface proteins $nl' and $nl2 with %-cadherin and the 3et receptor, respectively. (4) ninternalization, L.monocytogenes is engulfed in a phagocytic vacuole.(5) L. monocytogenes lyses vacuolar membranes by means of the toin LL.(6) L. monocytogenes uses the protein 'ct' to harness the actin polymerizationmachinery and facilitate its intracellular movement via the formation of so-calledactin 7comet tails.8 (9) L. monocytogenes eploits actin-based motility for direct

cell-to-cell spread to allow the dissemination of the infection to neighboring cells viathe formation of plasma membrane protrusions. (:) nce internalized byneighboring cells, L. monocytogenes is con!ned in a double-membrane vacuolefrom which it escapes to restart its life cycle.

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%pidemiology 1-19; of healthy humans are asymptomatic intestinal

carriers $nfections and diseases 3ost common in pregnant women,

3ild <=u-like> illness in 5rd trimester

can be transmitted to a newborn, via vaginal colonization or

placenta 3ay initiate abortion (miscarriage)

still birth

premature delivery

or infected newborn. 

epticemia and meningitis

between birth and third week of life  caused by serotype $? b and has a signi!cant mortality

rate

"ranulomatous skin lesions # rare

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Listeriosis In Adults

2acteremia and 3enigeoencephalitis =u-like symptoms for about four days

 occur most commonly in $mmunosuppressed patients in whom Listeria is one of the morecommon cause of 3eningitis

isease can be insidious to fulminant

iagnosis

iagnosis dependent on isolation of rganisms in

cultures obtained and direct microscopic eamination &@, 2lood, and other =uids narrow zone of beta-hemolysis

 /umbling movement, 3ovement in 49 A

 /reatment

'mpicillin

%rythromycin

$ntravenous #rimethoprim $ %ulphmetho&aole

&ephalosporins and @luroBuinoles are not active against L.monocytogens

' commination of "entamycin and 'mpicillin on clinical basis

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Ideal 'ay to preventListeriosis &ompletely cook all meats and eggs.

&arefully wash raw vegetables before eating. Ceep raw meat away from raw vegetables and prepared

foods. 'fter cutting raw meat, wash the cutting board withdetergent before using it for vegetables.

'void drinking unpasteurized milk or foods made from suchmilk.

Dash hands thoroughly after handling raw meat. @ollow the instructions on food labels. bserve food

epiration dates and storage conditions.

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Life cycle of

Listeria

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Listeria tumbling

motility

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