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Category:Staphylococcus species (view source)
Revision as of 22:58, 14 May 2010
, 22:58, 14 May 2010Created page with '{{review}} ===Overview=== *Commensals on skin and mucous membranes of animals and man *Enodgenous or exogenous infections *Opportunistic pyogenic infections associated with tra…'
{{review}}
===Overview===
*Commensals on skin and mucous membranes of animals and man
*Enodgenous or exogenous infections
*Opportunistic pyogenic infections associated with trauma, immusuppression, other infections
*'''Coagulase-positive''' ''S. aureus'' and ''S. intermedius'' as well as ''S. hyicus'' are important pathogens of animals
*Fairly stable in environment
*Strains selective for particular species
*Cause mastitis, tick pyaemia, exudative epidermitis, botryomycosis and pyoderma
===Characteristics===
*Clusters of Gram-positive cocci
*At least 30 species
*Facultative anaerobes
*Catalase positive, oxidase negative, non-motile
*Virulent strains are coagulase positive
*Grow on non-enriched media
*White or golden colonies
*''S. aureus'' and ''S. intermedius'' produce double haemolysis; they produce alpha-haemolysin and beta-haemolysin
*''S. hyicus'' is non-haemolytic
*Coagulase-negative strains vary in ability to cause haemolysis
*Slide test to detect bound coagulase (clumping factor) on surface of bacteria; bacteria clump within 1-2 minutes
*Tube test detects free coagulase, secreted by bactera; positive result indicated by clot formation in tube following 24-hour incubation; free coagulase converts prothrombin to thrombin which converts fibrinogen to fibrin
*Biochemical tests to differentiate ''S. aureus'' and ''S. intermedius''
*PCR to differentiate species
===Pathogenesis and pathogenicity===
*Cause suppurative lesions
*Trauma or immunosuppression predispose to infection
*Capsular polysaccharide, teichoic acids and potein A prevent opsonisation and therefore phagocytosis
*Cell wall proteins bind fibronectin and fibrinogen, allowing bacteria to attched to damaged tissues
*Coagulase, DNase and protein A production mark pathogenicity
*Haemolysins made by ''S. aureus'' and ''S. intermedius'' act as toxins
*Alpha-haemolysin prouces a narrow zone of complete haemolysis; this toxin causes necrosis and targets mast cells and plasma cells, whose contents cause damage
*Beta-haemolysin produces a wide zone of incomplete haemolysis; damages membranes and causes leakage, contributing to necrosis
*Also gamma and delta toxins
*Toxic shock syndrome toxin acts as a superantigen, which causes T cell proliferation and production of cytokines, leading to cardiovascular shock, with microthrombus formation in capillaries
*Enterotoxins produced by some strains of ''S. aureus'' cause food poisoning in humans
*Proteases, hyaluronidases and lipases facilitate survival of bacteria and spread and tissue destruction
===Diagnosis===
*Clusters of bacteria in Gram-stained smears of pus
*Culture on selective blood agar and MacConkey agar
*No growth on MacConkey
*Colony characteristics, haemolysis, catalase and coagulase production
*Phage typing for epidemiological studies
[[Staphylococcus aureus]]
===Exudative epidermitis ([[Bacterial skin infections - Pathology#Greasy pig disease|Greasy pig disease]])===
*Worldwide disease of pigs under 3 months of age caused by ''S. hyicus''
*Highly contagious and persists in the environment for long periods
*''S. hyicus'' produces exfoliative toxin that causes separation of cells in stratum spinosum resulting in rapid intraepidermal spread of organisms
*Similar to “scalded skin syndrome” in human neonates, due to skin infection by exfoliative toxin-producing ''Staphylococcus aureus''
*Excessive sebacious secretion and exudation on surface of skin
*Pigs are anorexic, febrile, depressed and have a greasy, non-pruritic dermatitis
*SKin thickened, wrinkled and scaley
*Acute death in piglets under 3 weeks due to dehydration and septicaemia
*20-100% morbidity; up to 90% mortality
*Organism enters skin via abrasions e.g. bite wounds
*Carried in vaginal mucosa and skin of sows
*Predisposed by lack of milk, weaning and other infections
*Piglets from non-immune sows are predisposed
*Passive transfer of antibodies from immune sows and development of immunity with age protect against disease
*Isolation from skin lesions
*Early systemic antibiotics amd topical antiseptics/antibiotics useful
*Disinfection after outbreak
*Wash sows before farrowing
*Differential diagnosis:
**Mange (''Sarcoptes scabiei var. suis'')
**Swine parakeratosis (zinc and essential fatty acid deficiency)
**Porcine juvenile pustular psoriasiform dermatitis (collarettes or rings typically on the ventrum of young pigs)
**Dermatosis vegetans (associated with a giant cell pneumonia)
**Dermatophytosis (most commonly ''Microsporum nanum'')
===Infections in dogs and cats===
*''S. intermedius'' causes [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]], otitis externa, mastitis, endometritis, cystitis, osteomyelitis, wound infections, [[Joints Inflammatory - Pathology#In Dogs|dyscospondylitis]]
*''S. aureus'' may cause [[Intestine Pathogens - Pathology#Staphylococcus|gastroenteritis]]
===Coagulase-negative staphylococci===
*Usually harmless commensals or secondary invaders
*May adhere to indwelling catheters leading to urinary tract infections
*Often display multiple antibiotic resistance
[[Category:Bacteria]][[Category:Gram_positive_bacteria]][[Category:Cocci]]
===Overview===
*Commensals on skin and mucous membranes of animals and man
*Enodgenous or exogenous infections
*Opportunistic pyogenic infections associated with trauma, immusuppression, other infections
*'''Coagulase-positive''' ''S. aureus'' and ''S. intermedius'' as well as ''S. hyicus'' are important pathogens of animals
*Fairly stable in environment
*Strains selective for particular species
*Cause mastitis, tick pyaemia, exudative epidermitis, botryomycosis and pyoderma
===Characteristics===
*Clusters of Gram-positive cocci
*At least 30 species
*Facultative anaerobes
*Catalase positive, oxidase negative, non-motile
*Virulent strains are coagulase positive
*Grow on non-enriched media
*White or golden colonies
*''S. aureus'' and ''S. intermedius'' produce double haemolysis; they produce alpha-haemolysin and beta-haemolysin
*''S. hyicus'' is non-haemolytic
*Coagulase-negative strains vary in ability to cause haemolysis
*Slide test to detect bound coagulase (clumping factor) on surface of bacteria; bacteria clump within 1-2 minutes
*Tube test detects free coagulase, secreted by bactera; positive result indicated by clot formation in tube following 24-hour incubation; free coagulase converts prothrombin to thrombin which converts fibrinogen to fibrin
*Biochemical tests to differentiate ''S. aureus'' and ''S. intermedius''
*PCR to differentiate species
===Pathogenesis and pathogenicity===
*Cause suppurative lesions
*Trauma or immunosuppression predispose to infection
*Capsular polysaccharide, teichoic acids and potein A prevent opsonisation and therefore phagocytosis
*Cell wall proteins bind fibronectin and fibrinogen, allowing bacteria to attched to damaged tissues
*Coagulase, DNase and protein A production mark pathogenicity
*Haemolysins made by ''S. aureus'' and ''S. intermedius'' act as toxins
*Alpha-haemolysin prouces a narrow zone of complete haemolysis; this toxin causes necrosis and targets mast cells and plasma cells, whose contents cause damage
*Beta-haemolysin produces a wide zone of incomplete haemolysis; damages membranes and causes leakage, contributing to necrosis
*Also gamma and delta toxins
*Toxic shock syndrome toxin acts as a superantigen, which causes T cell proliferation and production of cytokines, leading to cardiovascular shock, with microthrombus formation in capillaries
*Enterotoxins produced by some strains of ''S. aureus'' cause food poisoning in humans
*Proteases, hyaluronidases and lipases facilitate survival of bacteria and spread and tissue destruction
===Diagnosis===
*Clusters of bacteria in Gram-stained smears of pus
*Culture on selective blood agar and MacConkey agar
*No growth on MacConkey
*Colony characteristics, haemolysis, catalase and coagulase production
*Phage typing for epidemiological studies
[[Staphylococcus aureus]]
===Exudative epidermitis ([[Bacterial skin infections - Pathology#Greasy pig disease|Greasy pig disease]])===
*Worldwide disease of pigs under 3 months of age caused by ''S. hyicus''
*Highly contagious and persists in the environment for long periods
*''S. hyicus'' produces exfoliative toxin that causes separation of cells in stratum spinosum resulting in rapid intraepidermal spread of organisms
*Similar to “scalded skin syndrome” in human neonates, due to skin infection by exfoliative toxin-producing ''Staphylococcus aureus''
*Excessive sebacious secretion and exudation on surface of skin
*Pigs are anorexic, febrile, depressed and have a greasy, non-pruritic dermatitis
*SKin thickened, wrinkled and scaley
*Acute death in piglets under 3 weeks due to dehydration and septicaemia
*20-100% morbidity; up to 90% mortality
*Organism enters skin via abrasions e.g. bite wounds
*Carried in vaginal mucosa and skin of sows
*Predisposed by lack of milk, weaning and other infections
*Piglets from non-immune sows are predisposed
*Passive transfer of antibodies from immune sows and development of immunity with age protect against disease
*Isolation from skin lesions
*Early systemic antibiotics amd topical antiseptics/antibiotics useful
*Disinfection after outbreak
*Wash sows before farrowing
*Differential diagnosis:
**Mange (''Sarcoptes scabiei var. suis'')
**Swine parakeratosis (zinc and essential fatty acid deficiency)
**Porcine juvenile pustular psoriasiform dermatitis (collarettes or rings typically on the ventrum of young pigs)
**Dermatosis vegetans (associated with a giant cell pneumonia)
**Dermatophytosis (most commonly ''Microsporum nanum'')
===Infections in dogs and cats===
*''S. intermedius'' causes [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]], otitis externa, mastitis, endometritis, cystitis, osteomyelitis, wound infections, [[Joints Inflammatory - Pathology#In Dogs|dyscospondylitis]]
*''S. aureus'' may cause [[Intestine Pathogens - Pathology#Staphylococcus|gastroenteritis]]
===Coagulase-negative staphylococci===
*Usually harmless commensals or secondary invaders
*May adhere to indwelling catheters leading to urinary tract infections
*Often display multiple antibiotic resistance
[[Category:Bacteria]][[Category:Gram_positive_bacteria]][[Category:Cocci]]