Listeriosis Listeria Monocytogenes Dr Rayan Abdelwahid What is
Listeriosis Listeria Monocytogenes Dr. Rayan Abdelwahid
What is Listeriosis? Listeriosis is a serious infection caused by eating foods contaminated with the bacterium Listeria Monocytogenes. l This disease affects primarily pregnant women, newborn, and adults with weakened immune systems. l This bacterium is too small to be seen without a microscope. l
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
Symptoms l l l Fever Muscle ache GI Sx: Nausea, diarrhea Pregnant women: mild flu-like Sx, miscarriage, still birth, premature delivery, or infected newborn. Lethargy irritability l l If infection spreads to the nervous system: headache, stiff neck, confusion, loss of balance, or convulsions. Listeria can cause Pneumonia, Meningitis, and Sepsis.
Contamination l l l 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. l l l 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.
How do you get Listeriosis? l l l Eating food contaminated with Listeria. Babies can be born with Listeriosis if the mother eats contaminated food during pregnancy. Listeriosis is generally not contagious from person to person.
Diagnosis There is no routine screening test for susceptibility. l If you have Sx of fever, or stiff neck, consult your doctor. l A blood or spinal fluid test (to cultivate the bacteria) will show if you have Listeriosis. l During pregnancy, a blood test is the most reliable way to find out if your Sx are due to Listeriosis. l
Laboratory diagnosis l . l 1. Specimen collection, transport, processing l a Listeria from placenta l l l 2. Direct detection Listeria: small GPR; may form short chains and be confused with streptococci 3. Culture and identification l l i. difficult to isolate from this source; cold enrichment at 4 C for several weeks-months Listeria l i. grow well on BAP and CAP l ii. small white or translucent colonies; beta hemolytic l iii. CAMP positive iv. Motile; umbrella motility. Tumbling motility on wet prep and “umbrella-shaped” motility in semi-solid media at room temperature l l l X. Easculine positive Xi. Sodium hipurate positive xii Fermentation Xiii Catalase + Ix Oxidase +
Gram positive bacilli
Prevention • Thoroughly cook raw food from animal sources. • Was raw vegetables thoroughly before eating. • Separate uncooked meats from vegetables, cooked foods and ready-to-eat foods. • Avoid unpasteurized milk or food. • Wash hands, knives, and cutting boards with hot soapy water for at least 20 sec after handling uncooked foods. • Observe all expiration dates on food items. • Consume perishable and ready-to-eat foods as soon as possible. • Do not eat soft cheeses: feta, brier, camembert, blueveined, or Mexican-style etc. • Do not east refrigerated meat spreads, smoked salmon, smoked seafood; canned or shelf-stable smoked seafood may be eaten. • Listeria monocytogenes is killed by cooking or by heating methods, including pasteurization.
Treatment l l l Listeriosis is a serious disease requiring hospitilization. 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. Babies with Listeriosis receive the same antibiotics as adults. The duration of antibiotic treatment is at least 2 weeks. Even with prompt treatment, some infections result in death.
- Slides: 12