Difference between revisions of "Staphylococcus spp."

From WikiVet English
Jump to navigation Jump to search
Line 1: Line 1:
 
<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
 
<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
 
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
* [[General Pathology - Oedema#Permeability type|Permeability types of pulmonary oedema]]
 
 
* Can cause haemorrhagic disease by [[General Pathology - Haemostasis#Secondary Thrombocytopenic Disease|secondary thrombocytopenic disease]].
 
 
*May infect [[Joints - inflammatory#In Sheep|joints of sheep]]  [[Joints - inflammatory#In Pigs|arthritis in pigs]],
 
 
*''Staphylococcus'' spp. in [[Bacterial skin infections#Impetigo|impetigo]]
 
 
 
 
==Staphylococcus hyicus==
 
*Pigs - '''greasy pig disease'''
 
*Exudative epidermitis due to ''Staphylococcus hyicus'' is a worldwide problem in piglets. 
 
*The organism can often be isolated from the mucosa and skin of healthy adult pigs, and can persist in the environment for long periods. 
 
*Disease occurs only in young piglets up to about 35 days of age. 
 
*Passive transfer of antibodies from immune sows and development of immunity with age appear to adequately protect against disease. 
 
*Piglets from non-immune sows are predisposed. 
 
*Skin trauma, such as due to fighting, allowing entry of infective organisms is also considered a risk factor in this disease.
 
 
===[[Bacterial skin infections#Greasy pig disease|Pathology]]===
 
 
 
===Pathogenesis===
 
*''Staphylococcus hyicus'' produces an exfoliative toxin of approximately 30 kDa that causes separation of cells in the upper stratum spinosum resulting in rapid intraepidermal spread of organisms. 
 
*Death of affected piglets is common and is attributed to dehydration, septicemia, or both. 
 
*This porcine disorder has been likened to “scalded skin syndrome” in human neonates, due to skin infection by exfoliative toxin-producing ''Staphylococcus aureus''.
 
 
===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)
 
 
==Staphylococcus aureus==
 
 
* May cause [[Intestines - disease due to pathogens#Staphylococcus|gastroenteritis]] in small animals.
 
*[[Muscles - inflammatory#Botryomycosis|Botryomycosis]] in muscles
 
*In botryomycosis in [[Bacterial skin infections#Bacterial granulomatous dermatitis|skin]]
 
  
 
===Overview===
 
===Overview===
Line 111: Line 71:
  
  
===Exudative epidermitis (greasy pig disease===
+
===Exudative epidermitis ([[Bacterial skin infections#Greasy pig disease|Pathology]])===
  
 
*Worldwide disease of pigs under 3 months of age caused by ''S. hyicus''
 
*Worldwide disease of pigs under 3 months of age caused by ''S. hyicus''
*Highly contagious
+
*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
 
*Excessive sebacious secretion and exudation on surface of skin
 
*Pigs are anorexic, febrile, depressed and have a greasy, non-pruritic dermatitis
 
*Pigs are anorexic, febrile, depressed and have a greasy, non-pruritic dermatitis
*Acute death in piglets under 3 weeks
+
*Acute death in piglets under 3 weeks due to dehydration and septicaemia
 
*20-100% morbidity; up to 90% mortality
 
*20-100% morbidity; up to 90% mortality
 
*Organism enters skin via abrasions e.g. bite wounds
 
*Organism enters skin via abrasions e.g. bite wounds
 
*Carried in vaginal mucosa and skin of sows
 
*Carried in vaginal mucosa and skin of sows
 
*Predisposed by lack of milk, weaning and other infections
 
*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
 
*Isolation from skin lesions
 
*Early systemic antibiotics amd topical antiseptics/antibiotics useful
 
*Early systemic antibiotics amd topical antiseptics/antibiotics useful
 
*Disinfection after outbreak
 
*Disinfection after outbreak
 
*Wash sows before farrowing
 
*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'')
  
  
===Botryomycosis===
+
===[[Muscles - inflammatory#Botryomycosis|Botryomycosis]]===
  
 
*Chronic, suppurative granulomatous condition  
 
*Chronic, suppurative granulomatous condition  
Line 140: Line 110:
  
 
*''S. intermedius'' causes [[Bacterial skin infections#Deep pyoderma|deep pyoderma]], otitis externa, mastitis, endometritis, cystitis, osteomyelitis, wound infections, [[Joints - inflammatory#In Dogs|dyscospondylitis]]
 
*''S. intermedius'' causes [[Bacterial skin infections#Deep pyoderma|deep pyoderma]], otitis externa, mastitis, endometritis, cystitis, osteomyelitis, wound infections, [[Joints - inflammatory#In Dogs|dyscospondylitis]]
 +
*''S. aureus'' may cause [[Intestines - disease due to pathogens#Staphylococcus|gastroenteritis]]
 +
 +
 +
===Other infections===
 +
 +
**[[Bacterial skin infections#Impetigo|Impetigo]] in cattle and pigs
 +
** [[General Pathology - Oedema#Permeability type|Permeability types of pulmonary oedema]]
 +
**Haemorrhagic disease by [[General Pathology - Haemostasis#Secondary Thrombocytopenic Disease|secondary thrombocytopenic disease]]
 +
**May infect [[Joints - inflammatory#In Sheep|joints of sheep]]; [[Joints - inflammatory#In Pigs|arthritis in pigs]]

Revision as of 15:58, 20 July 2008

BACK TO INFECTIOUS AGENTS AND PARASITES
BACK TO BACTERIA

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
  • Alpha-haemolysin prouces a narrow zone of complete haemolysis, whereas beta-haemolysin produces a wide zone of incomplete haemolysis
  • Haemolysins act as toxins
  • 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
  • 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


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 (Pathology)

  • 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
  • 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)


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


Other infections