Staphylococci Flashcards
Intrammary mastitis and types of it
Udder cavity of ruminants invaded by bact causing inflam
Subclinical (incr SCC)
Clinical (mild and acute) inflam tender swelling clots in milk
Peracyte very severe systemic inflam gangrenous fever possibly fatal
Wound infections
Abscesses
Pustules
Various species as opportunistic
Pyoderma
Esp dogs
Commonly pseudintermedius as 2o factor after dam by allergy or parasites
And folliculitus
Tuck pyemia
Infection after dam by ticks esp ixodes ricinus
Abscesses in joints and other tissues
Exudative epidermitis (greasy pig disease)
Hyicus
Highly contagious and acute generalised skin infection in young animals
Dermatitis
Osteomyelitis
Arthritis
Poultry
Usually aureus
Cystitis
Esp dogs and cats
Paeudintermedius
Aureus
Septicaemia
Many animals incl rabbits
Infective endocarditis
Horse
Cow
Large breed dogs
Economic implications of mastitis
Cost uk farmers approx 93 mill a yr
USA approx 2 bill a yr
Clinical cases 1/5 of what they were in the 60s and sub clin (predominant form) also decr
Mastitis pathogenesis
Can colonise teat for long time periods
Penetrate teat duct with milk as a good nutrient source
Adherence to epi cells probs v important
Adherence virulence factors and why adherence important
Aureus
To initiate infection must access and attach to host cells or tissues
MSCRAMMs
Expr surf pros that attach to host pros like fibronectin and laminin in the ECM
Fibronectin also on epi and endo cells and a blood clot comp
Most strains expr clumping factor A a pro that binds fibrin/fibrinogen to promote attachment
Also most expr other fibrinectin/ogen bind pros and Fn binding pros med cell invasion
Capsular polysacc host D avoidance virulence factor of aureus
Most clinical isolate expr 5 or 8
Microcapsile as only viewed via electron microscopy after Ab labelling
Rapidly lose high polysacc level up in vitro culture from in vivo
Capsule res phagocyt
Serotype vary with strain
Staph pro A host D avoidance virulence factor of aureus
Surf pro that bind IgG by Fc region
Bind wring way round so disrupt opsonisation and phagocyt
Superantigens host D avoidance virulence factor of aureus
Stim T cells non-spec without normal antig recog
So cytok released in high amounts- detrimental to host and contrib to modulationof hist resp
Bind direct to MHC c2 of APC outside normal antig bind groove so complex recog on Vb element of T cell rec, so any T cell with matching Vb is stim, normal complex would also req antig spec in binding
Mem damaging alpha tox of aureus
Most potent mem dam tox
Expr as monomer and bind mem of susceptible cells
Subunits oligomerise and form hexameric rings with central pore
Beta toxin of aureus
Sphingomyelinase that dam mem rich in sphingomyelin
Test for this tox is sheep RBC lysis
Most human strains dont expr beta tox
Most mastitis strains do so thought to be important in mastitis pathogenicity
Delta tox of aureus
Small peptide tox prod by most strains of aureus
Also by epidermidis and lugdunensis
Has cytolytic activity
Gamma tox and leukocidins
Two component pro toxins that dam susceptible cell mem esp PMN
Aureus enzymes that are virulence factors
Proteases
Lipase
DNase
All provide nutrients, minor role in pathogenesis
FAME (fatty acid modifying enz)
Important in abscess as could modify antibact lipids and prolong bact survival
Varying host genetic susceptibilities and determinants for mastitis
SCC Lactoferrin Lysozyme MHC Udder depth Milking speed Milk production traits
Control of mastitis
Hygiene
Udder and teats washed pre milk
Disinfect post milk
Regularly clean and sterilise and service milking equip
Mastitis treatment
Antibio therapy Residues must be cleared before milk consumption Res increasing In vitro efficacy not a good predictor Use IL therapy?
Poultry infection
Aureus cause joint infection eg septic arthritis and BCO
Canine pyoderma what is it
Pseudintermedius (methicyllin res does exist) Common skin disease often 2o to atopic dermatitis - usually commensal
Canine pyoderma symptoms
Pruritus
Alopecia
Swelling
Erythema
Canine pyoderma treatment
Systemic antibios and topical shampoo
No effective vacc
S delphini
Assoc with horse pyoderma
S intermedius
Assoc with pigeon pyoderma
Exudative epidermitis symptoms and causative bact
Oozing fluid from inflamed skin
Hyicus - normally commensal but cause disease after abrasions. Produce exfoliative toxins causing skin lesion symptoms and liver and kidney dam
If liver dam then fatal
Exudative epidermitis epidemiology
Bact multiply in sows vagina days immediately pre farrowing and piglets often infected during or just after birth
Exudative epidermatitus treeatment
Antibio and inject daily for 5 days or with long acting antibio on alternate days
If sever outbreak an autogenous vacc can be prepped from org and has been effective on some farms
