Difference between revisions of "Category:Staphylococcus species"

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<categorytree mode=pages>Staphylococcus species</categorytree>
 
<categorytree mode=pages>Staphylococcus species</categorytree>
 
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===Overview===
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[[Category:Bacterial Organisms]]
 
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[[Category:Gram_positive_bacteria]]
*Commensals on skin and mucous membranes of animals and man
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[[Category:Cocci]]
*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
 
 
 
===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 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
 
 
 
==Enteritis==
 
* 30% strains of ''[[Staphylococcus aureus]]''  produce potent enterotoxin. T
 
** Protein and heat-stable
 
** Responsible for staphylococcal food poisoning in man.
 
* Every reason to assume that acute gastro-intestinal disturbance in small animals may be caused by these enterotoxins BUT not well documented.
 
* Symptoms last 24-36 hours and include:
 
** Acute vomiting
 
** Diarrhoea
 
** Pain
 
* The enterotoxins are superantigens.
 
** Induce release of cytokines from lymphocytes
 
 
 
 
 
 
 
 
 
'''sheep'''
 
 
 
*[[:Category:Staphylococcus species|'''''Staphylococci''''']]
 
**Sporadically infect joints
 
**May complicate 'tick-borne fever'
 
 
 
 
 
'''pigs'''
 
 
 
**Cause purulent arthritis
 
**In one or more joints
 
**Commonly contaminate wounds
 
 
 
 
 
'''dogs'''
 
 
 
**May cause '''discospondylitis'''
 
**Destructive inflammatory lesion
 
**Bacterial localise in ''[[Joints - Anatomy & Physiology#Fibrocartilagenous joints|''annulus fibrosis'']] -> may spread to local bone
 
 
 
[[Category:Bacteria]][[Category:Gram_positive_bacteria]][[Category:Cocci]]
 
 
[[Category:Enteritis,_Bacterial]]
 
[[Category:Enteritis,_Bacterial]]
[[Category:To_Do_-_Bacteria]]
 

Latest revision as of 21:34, 5 November 2010

Pages in category "Staphylococcus species"

The following 3 pages are in this category, out of 3 total.