Listeria Monocytogenes

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Listeria monocytogenes


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Listeria Monocytogenes:

Dr.T.V.Rao MD Listeria Monocytogenes Dr.T.V.Rao MD 1

What is Listeriosis:

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. Dr.T.V.Rao MD 2

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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 Dr.T.V.Rao MD 3


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. Dr.T.V.Rao MD 4

Who are at risk with Listeriosis:

Pregnant women New-borns People with weakened immune systems People who are taking immuno-suppressing medication. Who are at risk with Listeriosis Dr.T.V.Rao MD 5

Listeria Monocytogenes:

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 22 0 c – 28 0 c but not at 37 0 c But makes the Microbiologists to identify from Diptheriods, which are mistaken and specimens are discarded. Dr.T.V.Rao MD 6

Culture and Growth Characteristics:

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 4 0 c and plated on the media ( Cold enrichment ) Dr.T.V.Rao MD 7

Biochemical reactions:

Biochemical reactions Bacteria are facultative anaerobic microbes Catalase + motile Listeria produce acid and not gas in various sugar fermentation tests Dr.T.V.Rao MD 8

Camp positive listeria:

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) Dr.T.V.Rao MD 9

How Humans contact Listeriosis:

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. Dr.T.V.Rao MD 10

Pathogenesis and Pathology:

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 Dr.T.V.Rao MD 11

Who are at Higher Risk:

Who are at Higher Risk The following conditions may be impaired with defective cell mediated Immunity Pregnancy AIDS Lymphomas Organ transplant recipients Dr.T.V.Rao MD 12

Contamination causes Listeriosis:

Contamination causes Listeriosis Listeria Monocytogenes is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products. The bacterium has been found in uncooked meats and vegetables, soft cheeses, deli cold-cuts, and unpasteurized milk or foods. If acquired at birth, the incubation period is 7 to 28 days. The average incubation period is 31 days; with a range from 11 to 47 days. Dr.T.V.Rao MD 13


Symptoms Fever Muscle ache GI Sx: Nausea, diarrhea Pregnant women: mild flu-like Sx, miscarriage, still birth, premature delivery, or infected newborn. Lethargy irritability If infection spreads to the nervous system: headache, stiff neck, confusion, loss of balance, or convulsions. Listeria can cause Pneumonia, Meningitis, and Sepsis. Dr.T.V.Rao MD 14

Common presenting manifestation of Listeriosis:

Vomiting; Nausea; Cramps; Diarrhea; Severe Headache; Constipation; or Persistent fever. Common presenting manifestation of Listeriosis Dr.T.V.Rao MD 15

Listeriosis In Adults:

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 Dr.T.V.Rao MD 16

Listeriosis presenting with Meningitis:

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. Dr.T.V.Rao MD 17

Late onset manifestations:

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 Dr.T.V.Rao MD 18

Listeriosis and Pregnancy:

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. Dr.T.V.Rao MD 19

Listeriosis in New Borns:

Listeriosis in New Borns New-borns - New-borns rather than the pregnant women themselves suffer the serious effects of infection in pregnancy. Dr.T.V.Rao MD 20

Diagnosis :

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. 21


Diagnosis Diagnosis dependent on isolation of Organisms in cultures obtained on CSF, Blood, and other fluids Dr.T.V.Rao MD 22


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. Dr.T.V.Rao MD 23

Antibiotic Treatment:

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 Dr.T.V.Rao MD 24

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. Foods to Avoid Dr.T.V.Rao MD 25

Keep your food safe – avoid Listeriosis:

Keep your food safe – avoid Listeriosis Dr.T.V.Rao MD 26

Ideal way to prevent Listeriosis:

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. Dr.T.V.Rao MD 27

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Dr.T.V.Rao MD 28 Programme Created by Dr.T.V.Rao MD for Medical and Health Care Workers in the Developing World Email

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