111. Diseases of farm animals caused by staphylococci (rabbit, swine, poultry).

Question 1

Diseases caused by staphylococcus?

Answer 1

Diseases caused by staphylococcus

• Local purulent diseases
• Abscesses, metritis, mastitis, arthritis, dermatitis etc.
• Several host sp. (cattle, sheep, horse, pig, dog, cat)
• Horse: wound infection
• Dog: otitis externa (S. pseudointermedius)
• Morel’s disease
• Bronchopneumonia of rabbits caused by S. aureus
• Staphylococcosis of poultry
• Exudative dermatitis of swine
• Diseases caused by methicillin resistant S. aureus

Question 2

Staphylococcosis aetiology?

Answer 2

Staphylococcosis

• Aetiology – Gr +ve
• Coagulase positive
• S. aureus subsp. aureus A-E
• S. aureus subsp. anaerobius
• S. pseudointermedius (S. intermedius) – saprophyte
• Coagulase negative:
• S. hyicus (cause exudative dermatitis of pigs – pathogenic),
• S. epidermidis,
• S.,gallinarum,
• S. equinum
• Differences in virulence

Question 3

Staphylococci virulence factors?

Answer 3

Virulence factors

• Extracellular enzymes – coagulase (will be clotted if coagulase +ve),
• hyaluronidase (help the spread),
• lectinase (damage the tissue) etc.
• Toxins:
• haemolysins,
• leukocidins,
• enterotoxin (responsible for food poisoning in humans)
• Protein A (on the surface of the bacteria – can bind the Ig of the host from the FC part of the Ig not
• the Ag binding end = bacteria can mask themselves from the immune response of the host)
• Good resistance! (but not spore producing)

Question 4

Epidemiology, Pathogenesis, Clinical signs and diagnosis treatment and prevention of Staphylococci?

Answer 4

Epidemiology

• Part of the normal bacterium flora of MM & skin
• Lesions on the skin, MM are necessary for the bacteria to cause lesions
• Purulent lesions

Pathogenesis:

wound (enter the host) → virulence factors → local lesions

Clinical signs,

• lesions:
• dermatitis,
• botryomycosis (granule/abscess formation under the skin),
• inflammation of the external ear (S. pseudointermedius),
• abscess formation,
• arthritis, metritis, mastitis (clinical & subclinical)

Diagnosis

• Epidemiology – clinical signs – pathology
• Detection of the agent – culture
• Detection of the toxin – ELISA, PC

Treatment:

• ABs (resistance!!)

Prevention:

• avoiding wounds,
• aseptic vet treatment,
• prevention of enterotoxin production

Question 5

Morel’s disease?

Answer 5

Morel’s disease

• Occurrence: endemic in certain areas, sporadic
• Aetiology: S. aureus subsp. anaerobius
• Epidemiology
• Frequent above ½ year old – 3 years old (rarely older = resistance)
• Sheep & goat
• Slow, chronic disease (not seen in young)
• Pathogenesis: wound → LNs (abscesses – locally) → SC tissue, sometimes organs: abscesses
• Clinical signs: abscesses – beginning: hard, later: fluctuating, fistula
• Pathology: abscesses: LNs, SC tissue, sometimes organs
• Diagnosis: detection of the agent: smear, microscopy, bacterium culture
• Treatment, prevention: ABs, stamping out

Question 6

Rabbit staphylococcosis?

Answer 6

Rabbit staphylococcosis

• Occurrence: common, large scale farms

• Aetiology: S. aureus subsp. aureus – virulence variants

• Epidemiology

o Young, suckling, weaned, grower, sometimes adults (more frequently in young)

o Predisposing: overcrowding, poor bedding, bad climate in the stable, ammonia

• Pathogenesis

o Infections: aerogen, wounds → upper resp. airways → lungs → blood → septicaemia (arthritis, SC

abscesses, fistula, inflam. of the middle ear, mastitis, metritis)

• Clinical signs:

bronchopneumonia,

resp. signs (most important),

conjunctivitis, arthritis,

abscesses, middle ear infection, purulent inflammations

• PM lesions: bronchopneumonia, trachea mucous, abscesses

• Diagnosis:

• Epidemiology – clinical signs – PM lesions
• Bacterium isolation, smear

• Differential diagnosis:

• P. multocida,
• B. bronchiseptica (basically the same clinical signs)

• Treatment:

• macrolides (don’t change gut flora of rabbits) - erythromycin, tetracycline, elimination of the
• predisposing effects

Question 7

Poultry Staphylococcosis?

Answer 7

Poultry staphylococcosis

• Occurrence: common
• Aetiology:
• S. aureus
• (S. epidermidis, S. hyicus),
• S. intermedius (pigeon)
• Epidemiology
• Some lines are more susceptible
• (genetic predisposition)
• Predisposing factors
• Infective: gumboro disease,
• Marek disease,
• infectious chicken anaemia
• ▪ Non-infective: overcrowding, wounds, transportation, bedding, nutritional problems
• Pathogenesis
• Infection: egg, umbilical, aerogen, wound (cannibalism)
• Septicaemia (young birds)
• Local infection (growers, adults)
• Clinical signs
• Septicaemic form: embryonic death, omphalitis, weak animals, depression, listless, anorexia, death
• Arthritis form: enlarged joints, tenosynovitis, lame, does not move
• Dermatitis form: feathers fall out (head, back, wing), serous dermatitis, haemorrhages, serum →
• scab, gangrenous dermatitis (Clostridia)
• PM lesions
• Septicaemia: spleen & liver enlarge, haemorrhages, focal inflammation, necrosis
• Arthritis: oedema, haemorrhages, fibrin in the joints
• Dermatitis
• Diagnosis
• Epidemiology – clinical signs – PM lesions
• Bacterium isolation
• Differential diagnosis
• Septicaemia: E. coli, acute salmonellosis
• Arthritis: arthritis caused by reoviruses (reovirus & mycoplasma can be complicated by
• staphylococci), mycoplasmosis (synovitis), chronic salmonellosis, fowl cholera
• Dermatitis: fowl pox, gangrenous dermatitis, mycotoxins
• Treatment:
• elimination of predisposing factors,
• penicillin, tetracyclines, streptomycin, erythromycin,
• sulphonamide
• Prevention:
• prevent predisposing factors,
• S. epidermidis vaccine

Question 8

Exudative dermatitis of pigs(Greasy Pig disease)?

Answer 8

Exudative dermatitis of pigs (Exudative epidermitis, greasy pig disease)

• Occurrence: widespread, depending on management, sporadic
• Aetiology: S. hyicus (coagulase negative, exfoliative toxin – responsible for the lesions, hyaluronidase – help
• the bacterium to get into the skin & cause the lesions), present on the skin (normal microflora)
• Epidemiology
• 1-4 week old piglets: extended (mostly in suckling piglets)
• Older pigs: localised lesions
• Predisposing factors: overcrowding, ectoparasites, nutritional deficiencies (Zn, vits), wounds
• Clinical signs
• Whole body or localised lesions (frequently lesions on the head or the tail)
• Vesicles → pustules → ruptured (greasy) → scab
• Not itching, anorexia, udder or suckling sows
• Diagnosis: Epidemiology – clinical signs; Bacterium isolation
• Treatment, prevention: Penicillin, erythromycin, tetracycline; A-vitamin, biotin; Ectoparasites; Improving
• hygiene