Lecture 6 Flashcards
What is the biocontainment level for staphylococcus?
2
Is Staphylococcus gram positive or negative?
Positive
Describe the metabolism of staphylococcus
Aerobic or facultative anaerobes
Where is staphylococcus found?
Normal component of the microbiota
Found in: skin, mucous membranes, pharynx & the intestinal tract
What are the key virulence factors of staphylococcus? (4)
Toxic shock syndrome - non-specifically stimulate T cells which release high amounts of cytokines creating clinical symptoms
Enterotoxins - what is found in food poisoning
Exfoliatins - cause skin damage
Various leucocidins - destroy leukocytes
What disease does Staphylococcus aureus cause in bovine?
bovine mastitis
Describe the pathogenesis of bovine mastitis caused by Staphylococcus aureus
Udder is the main reservoir where it adheres and invades epithelial cells
Can form small colony variants - 1/10 the size of staph aureus enabling them to persist in cells
Can also form L-forms - no to little cell wall
Disease can be peracute (clinical disease) or subclinical (only see decres milk production)
Why is it so important to dx chronic subclinical mastitis?
Decres milk production –> economic loss
How do you tx bovine mastitis?
Improve hygiene - disinfect equipment & avoid milking affected quarter
Intra-mammary a/bs - be aware of methicillin resistance (beta-lactams won’t work)
What disease does Staphylococcus aureus cause in poultry?
Infection of a wide variety of sites - bones, tendons, sheaths & joints
Assoc with green-liver osteomyelitis complex, thought to be an immunosuppressive opportunistic infection
What are the symptoms of Staphylococcus aureus infection in poultry?
Surviving birds often have swollen joints
Reluctant to stand
May have gangrenous dermatitis of the feet (bumble foot)
Is there a concern for flock mortality in poultry with Staphylococcus aureus infections?
No, morbidity & mortality are usually low
Affects indivs rather than flocks
What is the pathogenesis of Staphylococcus aureus in poultry?
Not well defined
Opportunistic when host defences are compromised
What is the tx for staphylococcus aureus infections in poultry?
Good management practices to reduce stress & injury - remove sharp objects, having good quality litter, control of other diseases
Can vaccinate but not effective
Tx should be based on test results
What species is staphylococcus aureus found in?
Bovine
Poultry
What disease does Staphylococcus pseudintermedius cause in dogs?
Very commonly assoc with dogs (~90%)
When it does cause disease it causes a wide range or opportunistic infections
2nd most common cause of UTIs
Sx site infections
Orthopedic implants
Necrotizing fasciitis
Nosocomial infections
What organism is the mostly commonly found on the skin & ears of dogs?
Staphylococcus pseudintermedius
What is the pathogenesis of Staphylococcus pseudintermedius in dogs?
Opportunistic infection secondary to underlying disease (atopic dermatitis, food allergy, endocrine disease)
What is the tx for Staphylococcus pseudintermedius in dogs?
Need to address the primary issue
Determine site of infection
Superficial or deep pyoderma (deep in the dermis)
Inner vs outer ear infection
What disease does Staphylococcus hyicus cause in pigs?
Greasy Pig Disease
What are the symptoms of Greasy Pig Disease?
Exudative epidermitis
Acute or peracute
Sporadic occurrence
Seen in suckling & newly weaned piglets
Clinical disease seen following damage to skin seen when mixing litters, following fighting, unclipped teeth, rough bedding
What is the tx for Greasy Pig Disease?
Early tx with a/bs if caught early otherwise will die
High mortality rate, up to 70%
What disease does Staphylococcus chromogens cause?
Subclinical mastitis in bovine, ovine & caprine
What disease does Macrococcus caseolyticus cause?
Associated with skin & soft tissue infections in dogs
What disease does Macroccus canis cause?
Associated with skin & soft tissue infections in dogs
How do you collect a sample for Bovine Mastitis?
Collect milk sample immediately after milking (clean outside of teat before collecting)
Can also collect from bulk milk tank
How do you collect samples for dermatitis/surface?
Swabs
Pus
Exudates
How do you collect a sample for UTIs?
cysto is best (can also collect free catch)
How do you collect samples in poultry?
Yolk sacs
Joints
Stab swabs of internal organs
How do you handle Staphylococcus samples?
Pretty tough, no special transport required
DO NOT FREEZE (except milk samples)
How is Staphylococcus aureus identified in the lab?
Biochemically
How is Staphylococcus pseudointermedius identified in the lab?
Biochemically
How is Staphylococcus hyicus identified in the lab?
Biochemically
What test is run for all Staphylococcus samples?
Susceptibility testing
Is Staphylococcus zoonotic?
Has a very broad host range
Human Staphylococcus pseudointermedius infections are pretty rare
What drugs should we avoid using when treating Staphylococcus infections?
Polymyxins & Beta-lactams
