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(lis″en-sef′ă-lē) [Gr. lissos, smooth + encephalo-] Any of several developmental brain disorders in which the cerebral gyri do not develop normally and the surface of the brain appears less folded, i.e., smoother than normal. lissencephalous (lis″en-sef′ă-lŭs), adj. lissencephalic (lis″en-sĕ-fal′ik), adj.

Lister, Lord Baron Joseph

(lĭs′tĕr) British surgeon, 1827–1912, who developed the technique of antiseptic surgery, subsequently evolving into aseptic surgery, without which modern surgery would not be possible.


(lis-tēr′ē-ă) [Lister + -ia] A genus of gram-positive, non–spore-forming coccobacilli that may be found singly or in filaments. They are normal soil inhabitants.

L. monocytogenes The causative agent of listeriosis. This species lives in soil or the intestines of animals and may contaminate food, esp. milk or meat. Its growth is not inhibited by refrigeration.

listeriosis, listerosis

(lĭs-tĕr″ē-ō′sĭs, lĭs″tĕr-ō′sĭs) Infection with Listeria monocytogenes, which can cause a wide spectrum of food-borne illnesses from mild food poisoning to severe systemic disease in immunosuppressed patients, older adults, pregnant women, fetuses, and neonates (during the first 3 weeks of life).

Person-to-person transmission is primarily in utero or during passage through an infected birth canal. Other modes of transmission include inhalation of contaminated dust; contact with infected animals, contaminated sewage, mud, or soil, or with feces containing the bacteria. Most often contact with L. monocytogenes results in a transient asymptomatic carrier state, but sometimes bacteremia and a generalized febrile illness is produced. Transplacental infections may cause abortion, premature delivery, stillbirth, or early neonatal death, though the pregnant woman herself may experience only mild illness.

CAUSES: The organism may be found in unpasteurized milk, unprocessed soft cheeses, processed foods (such as lunch meats) contaminated after production, or fruits or vegetables contaminated by soil or water containing the organism. Unlike other food-borne pathogens, Listeria grows in refrigerated food.

INCUBATION PERIOD: Disease usually takes between one and three weeks to develop in exposed people although it may take considerably longer.

INCIDENCE: Although Listeria infections are rare, they are frequently grave. Mortality resulting from an outbreak of listeria can be as high as 20%.

SYMPTOMS AND SIGNS: In pregnant women, Listeria infects the amniotic fluid and causes spontaneous abortion, stillbirth, or premature birth with lethal listeriosis. In immunosuppressed adults and neonates, it most commonly causes meningitis.

DIAGNOSIS: Cultures of blood, urine, spinal fluid, or other normally sterile body fluids are used to confirm Listeria infection. During outbreaks pulsed-field gel electrophoresis is used to confirm that affected patients have been infected with a single strain of the bacterium.

PREVENTION: The organism is destroyed by heat; therefore the risk of contracting listeriosis derives from consuming foods ...

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