7,077 bytes removed ,  22:55, 14 May 2010
Line 1: Line 1: −
{{review}}
+
#REDIRECT[[:Category:Staphylococcus species]]
 
  −
{{toplink
  −
|backcolour =
  −
|linkpage =Bacteria
  −
|linktext =BACTERIA
  −
|pagetype=Bugs
  −
}}
  −
<br>
  −
===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
  −
 
  −
 
  −
===Bovine mastitis===
  −
 
  −
*''S. aureus'' is a common cause of mastitisin cattle worldwide
  −
*Most infections subclinical
  −
*Systemic infection can occur with peracute and gangrenous forms
  −
*In gangrenous mastitis, the quarter may become necrotic and slough off; alpha toxin causes necrosis of smooth muscle in blood vessel walls, reducing blood flow to the affected quarter, and causes release of lysomal enzymes from leukocytes
  −
 
  −
 
  −
===Tick pyaemia===
  −
 
  −
*Infection of lambs with ''S. aureus'' in hill-grazing areas of the UK
  −
*Lambs carry ''S. aureus'' on their skin and nasal mucosa; infection via skin trauma including tick bites
  −
*''Ixodes ricinus'' tick acts as a vector for ''Ehrlichia phagocytophila'', which causes immunosuppression in lambs, predisposing to staphylococcal infection
  −
*Acute septicaemia and death or localised abscess formation in many organs
  −
*Arthritis, posterior paresis and ill-thrift
  −
*Microscopic identification of bacteria in pus and isolation of ''S. aureus''
  −
*Prophylactic antibiotics e.g. tetracyclines initiated at 1 week of age may prevent infection
  −
*Tick control important
  −
 
  −
 
  −
===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'')
  −
 
  −
===[[Muscles Inflammatory - Pathology#Botryomycosis|Botryomycosis]]===
  −
 
  −
*Chronic, suppurative granulomatous condition
  −
*''S. aureus''
  −
*Occurs following castration of horses due to infection of stump of spermatic cors
  −
*Occurs in mammary tissues of sows
  −
*Mass of fibrous tissue containing pus and sinus tracts
  −
 
  −
 
  −
===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]]
  −
 
  −
 
  −
===Other infections caused by ''S. aureus''===
  −
 
  −
*[[Bacterial skin infections - Pathology#Impetigo|Impetigo]] in cattle and pigs
  −
* [[Oedema - Pathology#Permeability type|Permeability types of pulmonary oedema]]
  −
*Haemorrhagic disease by [[Haemostasis - Pathology#Secondary Thrombocytopenic Disease|secondary thrombocytopenic disease]]
  −
*May infect [[Joints Inflammatory - Pathology#In Sheep|joints of sheep]]; [[Joints Inflammatory - Pathology#In Pigs|arthritis in pigs]]
  −
*Dermatitis in sheep and goats
  −
*Arthritis and septicaemia in turkeys
  −
*Bumblefoot and omphalitis in chickens
  −
 
  −
 
  −
===Coagulase-negative staphylococci===
  −
 
  −
*Usually harmless commensals or secondary invaders
  −
*May adhere to indwelling catheters leading to urinary tract infections
  −
*Often display multiple antibiotic resistance
 
Author, Donkey, Bureaucrats, Administrators
53,803

edits