Gram positives week 5 Flashcards
Listeria characteristics
coccobacillary rods, facultative anaerobes, have flagella at 25 degrees.
Catalase pos, oxidase neg.
survive in pH 5.5-9.6
Psychrophilic - can grow in the fridge
Ubiquitous in the environment, normal in mammalian GIT. Resistant to harsh environmental conditions.
3 main clinical symptoms of Listeriosis
Encephalitis, septicemia, abortion
InlA and InlB pathogenic effect
adhesion. A attaches to enterocytes, B to hepatocytes
Disease name for listeriosis
circling disease, silage disease
Listeriosis in ruminants
encephalitis most common symptom. Affects all ages and both sexes, seasonal occurrence. Often due to spoiled silage. Can enter through ingestion, inhalation, or via breaks in oral/nasal mucosa
Listeriosis CS
anorexia, depression, twisting head to one side, walking in circles toward affected side, unilateral CNV and CNVII paralysis
Diagnosis of Listeriosis
history, symptoms, season, silage quality, specific lesions of the brain (microabscesses infiltrated by neutrophils/macrophages containing bact, meningitis, perivascular cuffing, neuronal necrosis). Culture brainstem tissue.
Septicemia - culture liver, spleen and blood
abortion - foetal abomasal content and uterine discharges
Listeriosis Tx and prevention
systemic therapy with antibiotics - septic listeriosis
neural listeriosis - poor response to anti-b’s
Prevention is key - check your silage, stop feeding if outbreak occurs
Erysipelothrix general characteristics
small rods usually in colony form, facultative anaerobes, non motile, catale and oxidase neg, found in tonsils of many species and slime layer of fish.
Up to 50% of healthy pigs have in their tonsils, carrier pigs excrete it in feces and oronasal secretions. Resistant to harsh environmental conditions
Transmission = ingestion
four erysipelothrix syndromes observed in pigs
septicemia, dermatopathy, arthritis, endocarditis
Listeriolysin O (LLO)
pore-forming cytolytic toxin – destroys membranes of phagosome
ActA protein (listeria)
actin-polymerizing protein
phospholipase C enzymes (PLC) - listeria
degradation of cytoplasmic and endocytic membranes
Neuraminidase (erysipelothrix)
cleaves sialic acid on endothelial cell surfaces, leads to hyaline thrombus formation.
important for adherence and invasion of endothelial cells
polysaccharide capsule
protection against phagocytosis and allows intracellular replication
hyaluronidase
dissemination of bacteria within tissues
spaA surface protein
adhesion
Swine erysipelas (diamond skin disease)
Acute form: sudden death, fever, stiff gait, skin lesions
subacute form: inappetance, fever, skin lesions
chronic form: arthritis, heart problems, endocarditis, polyarthritis, skin lesions
*diamond lesions pathognomonic
swine erysipelas susceptible groups
pigs 3 months - 1 year, stressed pigs may trigger disease
Swine erysipelas diagnosis
based on skin lesions, isolation of bacteria or PCR-based methods
Swine erysipelas treatment and control
Tx: acute form - isolate and treat with antimicrobials. Cull chronically affected animals
Control: good hygiene, vaccination before entering the breeding herd. Boars every 6 months, sows 3-4 week pre-farrowing
Erysipelas in turkeys
acute form: septicemia, sudden death
chronic form: endocarditis and weight loss
Non-suppurative polyarthritis
in lambs
organisms enter through umbilicus or castration wounds. post-dipping lameness due to cellulitis and laminitis in older lambs
Erysipeloid zoonosis
occupational hazard (vets, fish/pig industries). Enters through minor skin abrasions and causes cellulitis in fingers, diffuse skin infections, septicemia.
