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| − | <big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
| + | #REDIRECT[[:Category:Corynebacterium species]] |
| − | <big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
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| − | ===Overview===
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| − | *Common inhabitants of skin and mucous membranes of animals
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| − | *Opportunistic infections
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| − | *Cause pyogenic infections
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| − | *Most species host specific
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| − | ===Characteristics===
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| − | *Small, tough, Gram positive rods
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| − | *Pleomorphic
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| − | *Cluster together to resemble Chinese characters - coryneform morphology
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| − | *Known as diphtheroids
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| − | *Catalase positive, oxidase negative
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| − | *Facultative anaerobes
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| − | *Require enriched media for growth
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| − | *Non-motile
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| − | ===Pathogenesis and pathogenicity===
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| − | *Pyogenic causing suppurative infections except for ''C. bovis''
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| − | *''C. bovis'' causes mild neutrophil response in teat canal of healthy dairy cows and may protect from more pathogenic bacteria
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| − | *''C. pseudotuberculosis'':
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| − | **Facultative intracellular pathogen inside macrophages
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| − | **Cell wall lipid
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| − | **Produces a phospholipase toxin which hydolyses sphingomyelin in mammalian cell membranes
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| − | **Phospholipase may enhance survival and multiplication in host in early stages
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| − | *''C. renale''
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| − | **Urinary tract pathogens
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| − | **Produce urease and hydrolyse urea
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| − | **Possess fimbriae for attachment to urogenital mucosa
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| − | **Infection when immunity reduced or following tissue damage during parturition
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| − | ===''Corynebacterium pseudotuberculosis''===
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| − | *Caseous lymphadenitis:
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| − | **''C. pseudotuberculosis'' carried on skin of sheep
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| − | **Non-nitrate-reducing biotype
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| − | **Infection follows tissue trauma such as shearing wounds
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| − | **Incubation period 3 months
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| − | **Chronic suppurative infection of sheep, goats and occasionally cattle
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| − | **Abscessation of superficial and internal lymph nodes if haemtogenous spread occurs
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| − | **Caseous abscesses with green colour and onion ring appearance
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| − | **Ill thrift and pneumonia may occur
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| − | **Condemnation of carcasses and hides
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| − | **Infection spread by pus from abscesses, and oculonasal secretions
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| − | **Organism survives in environment for several months
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| − | **Sandwich ELISA detects circulating antibodies to phospholipase toxin
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| − | **Control: importation measures including screening; culling of infected sheep, stict hygiene; inactivated vaccine
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| − | *Ulcerative lymphangitis:
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| − | **Nitrate reducing biotype
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| − | **Disease in horses and cattle
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| − | **Infection through skin wounds
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| − | **Lymphangitis of lower limbs or abscessation in pectoral region
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| − | **Slow onset, usually becomes chronic
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| − | **Affected lymphatic vessels swollen and firm with nodules
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| − | **Oedema in affected limbs
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| − | **Ulcerative nodules exude thick green pus
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| − | **Lymphangitis and lymphadenitis in cattle with abscesses as well as coronary band lesions causing lameness
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| − | **Antibiotic treatment and topical iodophore shampoo
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| − | *May cause [[Muscles - inflammatory#Abscesses|myositis]]
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| − | *Involved in [[Bacterial skin infections#Deep pyoderma|deep pyoderma]]
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| − | ===''Corynebacterium renale''===
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| − | *''C. renale, C. pilosum, C. cystitidis''
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| − | *Found in the vulva, vagina and prepuce of normal cattle
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| − | *Bovine pyelonephritis
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| − | **Stress of parturition and short urethra predisposes cows to urinary tract infection
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| − | **Cystitis especially with ''C. cystitidis
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| − | **Ascending infection from bladder through ureters causes pyelonephritis
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| − | **Fever, anoexia, decreased milk production
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| − | **Restlessness; kicking of abdomen indicate renal pain
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| − | **Dysurea, arched back, bloody urine
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| − | **Chronic infection causes extensive renal damage
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| − | **Enlarged ureters and kidneys palpated per rectum
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| − | **Culture from urine; protein and red blood cells in urine
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| − | **Antibiotics e.g. penicillin for at least three weeks
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| − | *Ulcerative balanoposthitis (pizzle rot):
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| − | **Common in Merino sheep and Angora goats
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| − | **Ulceration around prepucial orifice with brown crust, and occasionally on vulva of ewes
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| − | **Bacteria hydrolyse urea to ammonia which causes mucosal irritation and ulceration
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| − | **High urine urea level, from high protein intake may predispose to condition
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| − | **High oestrogen levels in pastures also predisposes
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| − | **Castration and heavy wool aroung the prepuce are risk factors
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| − | ===Diagnosis===
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| − | *Samples include pus, exudate, affected tissues and urine
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| − | *Presence of coryneform organisms in smears
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| − | *Culture on blood agar, selective blood agar and MacConkey agar
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| − | *Do not grow on MacConkey
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| − | *Colony characteristics:
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| − | **''C. bovis'': lipophilic bacterium; small, white, dry, non-haemolytic colonies on plates inoculated with bovine milk
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| − | **''C. kutscheri'': white colonies; occasionally haemolytic
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| − | **''C. pseudotuberculosis'': small, white coloniess surrounded by narrow zone of complete haemolysis; colonies become dry and cream-coloured
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| − | **''C. renale'': small, non-haemolytic colonies after 24 hours; pigment produced after 48 hours
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| − | *Biochemical reactions:
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| − | **Certain strains of ''C. pseudotuberculosis'' reduce nitrates
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| − | **All pathogenic strains except ''C. bovis'' produce urease
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| − | *Enhancement of haemolysis produced by ''C. pseudotuberculosis'' when inoculated across a streak of ''Rhodococcus equi''
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