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Veterinary bacteriology: information about important bacteria
Veterinary bacteriology


Species/Subspecies: Staphylococcus aureus subsp. aureus
Categories: Zoonotic; causes hemolysis
Etymology: Genus name: bunch of grape-like cocci (coccus means a grain or berry)
Species epithet: golden
Subspecies epithet: see Species epithet
Significance:  [Very important]   
Taxonomy:
Phylum
Firmicutes
Class
Bacilli
Order
Bacillales
Family
Staphylococcaceae 
Genus
Staphylococcus
Type Strain: ATCC 12600 och 12600-U = CCUG 1800 = NCTC 8532.
Macromorphology (smell):
     
 

Medium (2-3 mm in diameter) sized, opaque, white or yellow colonies. Low convex and with smooth edges. They often give a double hemolysis zone on blood agar [a clear (complete) narrow inner zone, and a turbid (partial) broad outer zone].

The complete hemolysis of Staphylococcus spp. is caused by an α-hemolysin and the partial hemolysis by a β-hemolysin. Cf. Streptococcus spp.

Micromorphology: Non-motile cocci in clusters.
Gram +/Gram -:
 
G+
Metabolism: Facultatively anaerobic
Catalase/Oxidase:+/-
Other Enzymes: Coagulase + (most strains), esculinase -, urease +.
Biochemical Tests: Voges-Proskauer +
Fermentation of carbohydrates:
Staphylococcus aureus  
D-glucoselactosemaltoseL-rhamnosesucrose
+++-+
L-arabinosecellobioseD-mannitolsalicintrehalose
--+-+
glycerolinulinraffinoseD-sorbitolstarch
+?---
Other carbohydrates: mannose +.
Spec. Char.: S. aureus produces a polysaccharide kapsel.
Special Media:
Staphylococcus aureus  Staphylococcus aureus  Staphylococcus aureus  
Staphylococcus aureus  Staphylococcus aureus  

Baird-Parker agar is used for bacteriological analysis of food samples.

SELMA- or SELMA Plus plates are used for cultivation of milk samples when mastitis is suspected.

For cultivation of Methicillin Resistant Staphylococcus aureus (MRSA), selective media such as chromogenic media could be used.

Disease:
HostsDiseaseClinical picture
Most species, including humansSkin- and wound-infections, artritis abscesses, septicemiaLocal as well as systemic disease can invade the metaphyseal area of joints, leading to arthritis and/or osteomyelitis.
Cows, sheep and goatMastitisCommon udder pathogen, can be transmitted between cows, both subclinical and acute mastitis.
HorseSkin- and wound infectionsMost common cause of skin infection in horses often in mixed culture with Streptococcus zooepidemicus.
PoultryBumblefoot (pododermatitis)Swollen footpads and limping. Common cause of secondary infection after wounds on the feet, cause swollen footpads and limping.
HumansFood poisoningS. aureus can multiply in food and produce heat-stable toxinc, short incubation time and duration.
Virulence Factors: α-toxin (hemolysin) is a porin that causes cell death of sensitive cells, i.e. those cells that possess the receptor for α-toxin (platelets and monocytes).
β-toxin (hemolysin) is a sphingomyelinase (phospholipase).
γ-toxin (hemolysin) is also a porin, which can lyse sensitive cells.
δ-toxin (hemolysin) is a peptide composed of 26 amino acids, which acts as a biodetergent and can lyse many different types of cells.
Protein A is an outer membrane protein that binds to the Fc region of IgG molecules. Thus, the Fab regions will be exposed on the surface of the bacterium and that will prevent opsonization and phagocytosis.
Coagulase is an extracellular protein that binds to prothrombin and forms a complex (staphylothrombin), where the protease activity of thrombin will be initiated, so that fibrinogen is converted to fibrin. There is no conclusive evidence that coagulase is a virulence factor, but it is believed that the bacteria are protected against phagocytosis by causing local clots.
Genome Sequence:
Acc-noStrainSize (bp)Genome
NC_002951 Stam COL 2 809 422 1c +1c 
Totalt har 16 stammar sekvenserats och de har 0-3 cirkulära plasmider.

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
D83357  ATCC 12600T 1 476 

Taxonomy/phylogeny:
 
About 70 species and subspecies have been described within the genus Staphylococcus. S. aureus subsp. aureus is as the name implies closely related to S. aureus subsp. anaerobius.
Comment:Streptococcus pyogenes is also causing impetigo in humans.
Reference(s): No. 16, 42, 50
Updated:2021-10-11

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The revised taxonomy of the mollicutes

The revised taxonomy of mollicutes (mycoplasmas) has now been introduced on VetBact, which means that many of the species have been given new genus names or moved to another higher taxon. 

Published 2021-11-25. Read more...

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