Listeria

• gram positive

• L. monocytogenes have typical coccobacilli

• colonies are small, smooth, transparent

Morphology

in environment on herbage and freshwater, and may be present in feces and sewage

Listeria is usually found in

• grow on non-enriched media

• facultative anaerobes

• catalase positive

• oxidase negative

Biochemical characteristics

motile at 25°C w/ tumbling movement due to peritrichous flagella

are Listeria spp. motile or non-motile?

encephalitis, abortion, septicemia, endophthalmitis

disease/s that L. MONOCYTOGENES causes in SHEEP, CATTLE, & GOATS

abortion, septicemia, endophthalmitis

disease/s that L. MONOCYTOGENES causes in PIGS

septicemia

disease/s that L. MONOCYTOGENES causes in BIRDS

abortion

disease/s that L. IVANOVII causes in SHEEP & CATTLE

meningoencephalitis (rare)

disease/s that L. INNOCUA causes in SHEEP

• pattern of hemolysis in sheep blood agar

• CAMP tests

• Acid production from short range of sugars

• cerebrospinal fluid and tissue from medulla and pons should be samples

• specimens for abortion cases: cotyledons, fetal abomasal contents, uterine discharges

Methods of diagnosis of Listeria

• small haemolytic colonies on blood agar

• Aesculin hydrolysis

• Tumbling motility

• Positive CAMP test with S. aureus

Identification criteria for L. monocytogenes

• septicemia, encephalitis, abortion

• organism penetrates M cells in Peyer’s patches in intestine and spread via lymph and blood

• In pregnant, animals, there is transplacental transmission

• can invade through breaks in nasal & oral mucosa which can lead to NEURAL LISTERIOSIS

Pathogenesis of L.monocytogenes

• outbreaks in silage-fed animals in late pregnancy

• dullness, circling, tilting of head

• unilateral facial paralysis

signs of listeria

14-40 days

incubation period for neural listeriosis