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Bacteriology Flashcards

1
Q

Staphylococci

What are the 4 main Staphylococcal diseases in small animals

A

All caused by S. pseudointermedius
1. Pyoderma
2. Skin abcesses
3. Otitis externa
4. Urinary tract infections

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2
Q

Staphylococci

What are the main staphylococcal diseases in
a) Cattle
b) Pigs
c) Lambs
d) Horses

A

a) Mastitis (S. aureus)
b) Dermatitis in young pigs, greasy pig disease (S. hyicus)
c) Tick pyaemia (S. aureus)
d) Spermatic cord castration abscesses (S. aureus)

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3
Q

Staphylococci

Staining characteristics of Staphylococci

A
  • gram positive cocci
  • spherical and uniform
  • form clusters, in pus they clump irregularly ‘bunch of grapes’
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4
Q

Staphylococci

a) Define biofilm
b) What are consituents of the staph biofilms
c) Significance of formation

A

a) Multilayered structure made of bacteria embedded in an extracellular polymeric matrix
b) Polysaccharide capsule, cell wall teichoic acid, peptidoglycan and surface proteins
c) Form round surgical implants, reduces complement activation and deposition, makes treatment difficult (antibiotic cannot reach all bacteria)

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5
Q

Staphylococci

Surface proteins that control the following
a) Adhesion to host epithelium
b) Complement inhibition
c) Phagocyte inhibition

A

a) Adhesins -> bind to extracellular matrix, mediate first step of colonisation
b) Protein A fixes complement (prevents cascade), binds antibody, inhibits ADCC
c) Peptidoglycans inhibit phagocyte chemotaxis to infection site and are antiphagocytic

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5
Q

Staphylococci

Exotoxins
a) Haemolysins
b) Coagulase
c) Leucocidin

A

a)
- β-haemolysin is unique to animals. produces incomplete haemolysis of sheep and bovine RBCs at 37C, but complete haemolysis when stored at 4-15C (hot-cold lysis)
- α-haemolysin produces complete haemolysis of sheep and bovine RBCs and disrupts phagocyte lysosomes

b)
- produced by all pathogenic staph
- causes coagulation of plasma proteins (inc complement)

c)
- causes phagocyte necrosis

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6
Q

Staphylococci

Exotoxins
a) Hyaluronidase
b) Staphylokinase
c) Exfolative toxin
d) Enterotoxins

A

a) Assists tissue invasion
b) Plasminogen activator and lipase
c) Causes skin erythema, exfoliation and crusting
d) Causes enteritis

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7
Q

Staphyococci

Laboratory diagnostics
a) Culture conditions
b) Biochemistry markers
c) Haemolysin consideration

A

a)
- Grow at 37C
- Grow both aerobically or anaerobically
- Colonies appear over night
- S. aureus produces pigments in its cell wall giving it a yellow colour, other species do not

b)
- Coagulase positive
- Sugar fermentation aids species identification

c)
- β-haemolysin (‘hot-cold lysis’) is characteristic for animal Staph

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8
Q

Staphylocicci

Describe penicillin resistance in Staph species

A
  • β-lactamase (bla) production destroys the penicillin β-lactam ring -> clavulanic acid is a β-lactamase inhibitor, used in potentiated penicillins
  • target modification: alteration of penicillin binding protein (PBP 2a), encoded by mecA gene -> MRSA
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9
Q

Pasteurella family

Pasteurellaceae family
a) Main genera of disease causing bacteria in animals (4)
b) Bacteria features
c) Clinical importance

A

a)
- Pasteurella & Mannhemia
- Actinobacilus
- Haemophilus

b)
- aerobic
- gram negative rods

c)
- responsible for majority of bacterial pneumonias in farm animals (along with Strep.)
- are commensals of URT, but cause disease when host defence is compromised
- vaccination widely used for sheep and pigs (not cattle)

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10
Q

Pasteurella family

Pasteurella - important pathogens in
a) Sheep
b) Cattle
c) Pigs
d) Horses
e) Rabbits

A

a)
- M. haemolytica (adult pneumonia, lamb septicaemia)
- B. trehalosi (systemic pasteurellosis)

b) (shipping fever, calf pneumonia)
- M. haemolytica
- P. multocida

c) (atrophic rhinitis)
- P. multocida

d) (pleuropneumonia, inflammatory airway disease)
- P. caballi

e) (rhinitis, sinusitis)
- P. multocida

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11
Q

Pasteurella family

Pasteurella pathogenesis
a) Capsule
b) Cell wall
c) Surface proteins
4) Secreted proteins

A

a)
- antiphagocytic

b)
- contains endotoxin LPS: inflammatory mediator, responsible for hyperacute nature of septicaemias

c)
- adhesins, especially outer membrane proteins (OmpA)
- iron binding proteins

d)
- haemolysins
- leukotoxin
- hyluronidase
- cytolytic toxin

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12
Q

Pasteurella family

Pasteurella diseases in sheep
a) Pneumonia in adult sheep and septicaemia in lambs (causative agent, laboratory diagnostics, clinical importance)
b) Systemic pasteurellosis (causative agent, laboratory diagnostics, clinical importance)

A

a)
- Cause: M. haemolytica
- Lab: small grey colonies, haemolytic on sheep blood agar. Ferments arabinose
- Clinical: acute pleuropneumonia in adult sheep between May and July. Septicaemia in lambs up to 12 weeks

b)
- Cause: B. trehalosi
- Lab: larger grey/brown colonies, haemolytic on sheep blood agar. Ferments trehalose
- Clinical: septicaemia in sheep aged 6-9 months in autumn

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13
Q

Pasteurella family

Pasteurella diseases of cows
a) Calf pneumonia complex (causative agent, laboratory diagnostics, clinical importance)
b) Shipping fever (causative agent, clinical importance)

A

a)
- Cause: mainly M. haemolytica, sometimes P. multocida
- Lab: M. haemolytica - small grey colonies, haemolytic, ferments arabinose. P. multocida - small colonies, non-haemolytic
- Clinical: usually secondary to viral infection. Calves often have mixed infection of other bacterial species

b)
- Cause: mainly M. haemolytica, sometimes P. multocida
- Clinical: induced by long distance transport. Often part of a mixed infection

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14
Q

Pasteurella family

Pasteurella diseases in pigs
Atrophic rhinitis (causative agent, important pathology)

A
  • Cause: P. multocida type D (mixed infection with Bordetella bronchiseptica)
  • Pathology: produces exotoxin that destroys turbinate bone -> distorted snouts and loss of turbinates of young pigs
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15
Q

Pasteurella family

Pasteurella
a) Treatment
b) Vaccination in sheep
c) Vaccination in cattle
d) Vaccination in pigs

A

a) Sensitive to a wide range of antibiotics (aminoglycosides, tetracyclines, trimethoprim-sulphonamides)
b) M. haemolytica and B. trehalosi vaccines widely used
c) M. haemolytica vaccine available, but not widely used
d) P. multocida vaccine used

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16
Q

Pasteurella family

Actinobacillus disease
a) Pigs
b) Cattle

A

a)
- A. pleuropneumoniae
- Pleuropneumonia outbreaks in densly stocked pigs

b)
- A. ligniersi
- Causes ‘wooden tongue’ - granulomatous tongue abscessation

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17
Q

Pasteurella family

Actinobacillus disease in horses
a) Neonatal septicaemia
b) Pleuropneumonia
c) Inflammatory airway disease

A

a)
- A. equuli equuli (non-haemolytic)
- Infection acquired from dam

b)
- A. equuli haemolyticus (haemolytic)

c)
- A. equuli haemolyticus (haemolytic)
- Mixed infection

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18
Q

Pasteurella family

Actinobacillus
a) Treatment
b) Vaccination

A

a)
- sensitive to wide range of antibiotics (aminoglycosides, tetracyclines, trimethoprim-sulphonamides)
- wooden tongue treated with sodium iodide

b)
- A. pleuropneumoniae (pigs) vaccination used

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19
Q

Pasteurella family

Haemophilus infections
a) Cattle
b) Pigs
c) Vaccinations available

A

a)
- H. somnus
- Causes pneumonia, septicaemia (when bacteria reaches CNS and joints it causes meningoencephalitis and polyarthritis)

b)
- Glaesserella parasuis
- Causes pneumonia, Glassers disease (septicaemia with polyserositis)

c) For pigs, Glaesserella parasuis/Mycoplasma hyopneumoniae vaccines used

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20
Q

Bordetella and Moraxella

Bordatella
a) Bacterial features
b) Pathogenesis

A

a)
- gram negative, strictly aerobic, mostly haemolytic
- produce blue/grey colonies on MacConkey
- catalase and oxidase positive
- no fermentation
- exclusively respiratory

b)
- adhere to beating cilia and cause death to these cells, allowing secondary infection by another pathogen
- surface adhesins and pili adhere to cilia
- cytotoxins paralyse and destroy ciliated cells
- global virulence regulator gene bvg regulates virulence factors (phase variation)

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21
Q

Bordatella and Moraxella

Bordatella diseases
a) Dogs
b) Pigs
c) Treatment
d) Vaccination

A

a)
- B. bronchiseptica
- Causes infectious tracheobronchitis (kennel cough)
- May follow primary infection by PI3 or adenovirus

b)
- B. bronchiseptica
- Causes atrophic rhinitis (along with P. multocida)

c)
- sensitive to most antibiotics (although as kennel cough is multi-agent, often responds poorly to treatment)
- pigs showing clinical signs show little response to antibiotics as turbinates have already been destroyed

d)
- Dogs: live attenuated intranasal vaccine
- Pigs: killed vaccine with P. multocida toxoid

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22
Q

Bordatella and Moraxella

Moraxella
a) Bacteria features
b) Disease in cattle
c) Treatment
d) Vaccination

A

a)
- Gram negative, strictly aerobic, haemolytic
- Oxidase positive
- No fermantation
- Commensals of bovine conjunctiva

b)
- M. bovis
- Causes infectious bovine keratoconjunctivitis (New Forest eye) - progressive ulceration of cornea and possible globe rupture

c) Treated with tetracycline (subconjunctival injection) or cloxacillin (topical ointment)

d) No vaccines

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23
Q

Chlamydias

a) Describe bacterial features of chlamydophilia (5)
b) Methods of immune evasion (4)
c) General consequences of infection

A

a)
- gram negative
- obligate intracellular bacteria
- replicate within endosomes
- elementary body (EB) is infectious form
- reticulate body (RB) is replicative form

b)
- inhibit phagolysosomal fusion
- inhibit apoptosis
- proteolytic cleavage of NF-κB
- downregulate MHC class II

c)
- cessation of DNA, RNA and protein synthesis within host cell
- autolysis

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24
Q

Chlamydia

a) Methods of transmission (3)
b) Diagnosis techniques (4)
c) Antibiotic treatment
d) Vaccine availability

A

a)
- depends on host species habitat and lifestyle
- faeco-oral transmission
- droplet transmission
- contact with infected aborted material

b)
- Staining
- Culture
- ELISA
- PCR

c) Tetracyclines
d)
- Vaccines available for ruminants (C. abortus)
- Vaccines available for C. felis
- No vaccine for C. psittaci

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25
Q

Chlamydia

Clinical signs of infection of
a) C. felis
b) C. abortus
c) C. psittaci

A

a)
- Conjunctivitis in kittens - may also cause keratitis and corneal ulceration
- Respiratory disease - forms part of the feline upper respiratory tract infection complex

b)
- Abortion - causes ovine enzootic abortion, infection is initially asymptomatic, but ewe will abort ~90 days during her next pregnancy due to placentitis
- Zoonotic potential

c)
- Respiratory disease - respiratory and GI signs in birds (psittacosis)

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26
Q

Mycoplasma

a) Bacterial features (3)
b) Methods of causing cell damage (4)

A

a)
- gram negative
- faculative anaerobes
- lack a cell wall (resistant to antibiotics that target cell wall, eg penicillins)

b)
- inhibit/destroy cilia
- toxin production (hemolysins, proteases, nucleases)
- complement activation
- cytokine activation

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27
Q

Mycoplasma

a) Immune evasion mechanisms (6)

A
  • inhibit phagocytosis
  • persist within phagocytes
  • latent infection
  • molecular mimicry
  • antigen variability
  • activation of polyclonal B cells
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28
Q

Mycoplasma

Clinical signs of infection in birds
a) M. gallisepticum
b) M. synoviae
c) M. meleagridis and M. iowae

A

a)
- chronic respiratory disease, sinusitis and airsacculitis in domestic poultry

b)
- synovitis, lameness and leg deformities

c)
- leg and spine deformities

29
Q

Mycoplasma

Clinical signs of infection in pigs
a) M. hyopneumoniae
b) M. hyorhinis
c) M. hyosynoviae

A

a)
- chronic non-productive cough, retarded growth (high morbidity, low mortality)

b)
- fever, polyarthritis and polyserositis in piglets < 10 weeks old

c)
- synovitis, arthritis and lameness

30
Q

Mycoplasma

Clinical signs of infection in cattle
a) M. mycoides
b) M. bovis
c) M. dispar
d) M. bovigenitalium

A

a)
- contagious bovine pleuropneumonia

b)
- most commonly causes respiratory disease in calves
- can cause arthritis, mastitis and pneumonia in older cattle

c)
- pneumonia

d)
- reproductive disease

31
Q

Mycoplamsa

a) Diagnosis of infection
b) Antibiotic treatment
c) Other treatment

A

a)
- PCR
- Cultivation
- Serology (western blot, ELISA)

b) Tetracyclines, fluoroquinolones, macrolides (although infections are difficult to eliminate)

c) Isolation or culling

32
Q

Brachyspira

B. hyodysenteriae - swine dysentery
a) Clinical signs (4)
b) Pathogenesis (3)

A

a)
- faeces containing mucus, necrotic tissue and blood
- moderate fever, depression
- 25% mortality
- spontaneous remissions and relapses

b)
- colonises mucus-filled intestinal crypts
- invades and multiplies in goblet cells, spreading to enterocytes
- haemolysins/cytotoxins cause tissue damage

33
Q

Bacillus

Bacullus anthracis
a) Bacterial features (4)
b) Route of infection
c) Virulence factors (4)

A

a)
- gram positive
- large, endospore forming rods
- oxygen induces spore formation
- capsule stains pink with methylene blue

b)
- ingestion of spores (oral)
- inhalation of spores
- biting insects

c)
- capsule
- edema toxin
- lethal toxin
- protective antigen

34
Q

Bacillus

B. anthracis clinical signs
a) In cattle and sheep (4)
b) In pigs and horses (3)

A

a)
- sudden death with no signs of disease
- fever, loss of appetite, dry cough
- fits, colicky pains
- bright staring eyes

b)
- hot painful throat swellings
- sudden colic in horses
- loss of appetite

35
Q

Clostridium

a) Bacterial features
b) C. perfringens toxins (4)

A

a)
- gram positive, spore-forming rods
- toxin producing
- obligate anaerobes

b)
- alpha: lecithinase, acts on cell membranes
- beta: necrotising, inactivated by trypsin
- epsilon: damages vascular endothelium and gut epithelium, activated by proteases (including trypsin), colostrum prevents activation
- iota

36
Q

Clostridium

C. perfringens enterotoxaemia disease
a) Type A
b) Type B
c) Type C
d) Type D
e) Type E

A

a)
- enterotoxaemia with jaundice in lambs

b)
- lamb dysentery

c)
- haemorrhagic enterotoxaemia in piglets, lambs, foals, calves
- struck in sheep
- necrotic enteritis in chickens

d)
- pulp kidney disease in lambs (due to excess glucose in kidneys), encephalomalacia for same reasons

e)
- enterotoxaemia in calves

37
Q

Clostridium

a) Diagnosis of enterotoxaemia
b) Vaccination

A

a)
- clinical signs
- gram-stained smears (large numbers of large gram-positive rods)
- toxin demonstration using mice, neutralisation test to identify
- glycosuria and encephalomacia in pulp kidney disease

b)
- vaccination with specific toxoid possible
- ewe/sow vaccination recommened
- antiserum immediately administered during an outbreak

38
Q

Clostridium

Clostridia affecting the liver (2) and disease they cause

A
  • C. novi type B: black disease (infectious necrotic hepatitis) - affects sheep, commonly with liver fluke damage - grey-yellow foci in liver
  • C. haemolyticum: bacillary haemoglobinuria - affects cattle, commonly with liver fluke damage - pale liver infarction, surrounded by blue-red zone
39
Q

Streptococci

a) Bacterial features
b) Features contributing to pathogenicity

A

a)
- ubiquitous commensals of upper respiratory tract, lower genital tract and udder
- gram positive cocci that form chains
- catalase negative

b)
- capsule: protect from phagocytosis
- adhesins: mediate adhesion
- M protein: complement inhibition and immunogen
- C substance: immunogen, used for lancefield grouping
- Secreted proteins: haemolysins, other exotoxins
- Superantigens

40
Q

Streptococci

a) Group A
b) Group B
c) Group D
d) Group G

A

a)
- commensal of human nasopharynx
- causes pharyngitis, scarlet and rheumatic fever, toxic shock, necrotising fasciitis

b)
- commensal of GI and genitourinary tract
- leading cause of neonatal pneumonia and meningitis
- cause mastitis in dairy cattle, sepsis in farmed fish

c)
- enterococcus, commensal of GI tract of all animals
- resistant to antibiotics (cause of hospital-acquired infections)

d)
- carried by dogs and cats in nasopharynx, reproductive tract and on skin
- cause opportunistic infections (dermatitis, UTI, otitis externa, eye ulcers etc)

41
Q

Streptococci

Important features
a) S. suis
b) S. uberis
c) S. pneumoniae

A

a)
- α-haemolytic
- endemic in pigs
- can cause septicaemia, endocarditis, polyarthritis, pneumonia, meningitis
- zoonotic

b)
- non-haemolytic, no lancefield antigen
- carried by cattle and multiplies in environment
- can cause mastitis

c)
- α-haemolytic in aerobic conditions
- many serotypes
- resistant to most major antibiotics (penicillin, macrolides)

42
Q

Streptococci

Important features
a) S. zooepidemicus
b) S. equi

A

a)
- wide range of infections
- respiratory disease, abortion, keratitis in horses
- acute fatal haemorrhagic pneumonia in dogs
- respiratory disease, mastitis, abortion in ruminants and pigs
- zoonotic

b)
- subspecies of S. zooepidemicus
- causes strangles (abcesses in lymph nodes of head and neck), very contagious
- disease surveillance most important
- vaccination available

43
Q

Clostridium

a) Neurotoxic clostridia (2)
b) Histotoxic clostridia (3)

A

a)
- C. tetani (tetanus)
- C. botulinum (botulism)

b)
- C. chauvoei (blackleg)
- C. septicum (malignant oedema)
- C. novyi Type A (gas gangrene, big head in rams)
- C. novyi Type B (black disease - necrotic hepatitis)

44
Q

Clostridium

C. tetani
Route of infection and pathogenesis

A
  • spores from soil enter through open wounds (anaerobic condition) - especially puncture or lacerating wounds
  • spores germinate, producing tetanus toxin (TT) which enters the bloodstream
  • TT enters nerve ends, migrates retrogradely through peripheral nerves to CNS, where toxin prevents inhibitory transmitter release (GABA, glycine) from inhibitory interneurons - by cleaving synaptobrevin, preventing transmitter release
  • results in uncoordinated muscle tone and contraction, causing spastic paralysis
45
Q

Clostridium

C. tetani
a) Early clinical signs
b) Later clinical signs
c) Diagnosis and treatment
d) Vaccine

A

a)
- often appear cranially (facial muscles and eyelid spasms)

b)
- limb rigidity
- lockjaw (facial muscle rigidity)
- neck extension
- raised tail

c)
- diagnosis based on clinical signs
- treatment relies on wound debridement, muscle relaxation, antitoxin, antibiotics

d)
- toxoid-based vaccine
- combine vaccine with immune-prophylaxis/therapy with antisera given as soon as possible

46
Q

Clostridium

C. botulinium
a) Route of infection and pathogenesis
b) Clinical signs
c) Treatment
d) Vaccination

A

a)
- ingestion of food containing preformed toxin
- toxin acts at NMJ, inhibiting ACh release and preventing muscle contraction (flaccid paralysis)

b)
- flaccid paralysis, circulatory failure, respiratory paralysis

c)
- IV antitoxin
- Assisted ventilation may be required

d)
- toxoid based vaccine available

47
Q

Clostridium

C. chaevoei - black leg
a) Route of infection and pathogenesis
b) Gross pathology
c) Diagnosis
d) Vaccination

A

a)
- endogenous infection of cattle, sheep and goats - spores live in intestine and can be found in soil
- spores ingested, migrate to muscle via blood or lymph and persist in muscular tissue
- trauma to infected muscle (reduces oxygen due to initial necrosis) causes spores to germinate, releasing toxins
- toxins damage tissues (cytolysins, hyaluronidase, DNAses)

b)
- localised damage, necrosis of muscle (black appearance)
- gas and rancid odour
- terminal toxaemia

c)
- clinical signs, and presence of bacteria in tissues

d)
- toxoid vaccines available

48
Q

Clostridium

C. septicum - malignant oedema
a) Route of infection and pathogenesis
b) Clinical signs
c) Vaccination

A

a)
- found in intestines and soil
- pathogenesis usually associated with exogenous infection through wounds (malignant oedema and gas gangrene)
- sometimes endogenous infection
- tissue distruction due to toxin damage

b)
- malignant oedema and gas gangrene in horses, pigs, cattle, sheep
- endogenous infection in sheep (Braxy): necrotic lesions and haemorrhagic oedema of abomasal and duodenal wall

c)
- toxoid vaccines available

49
Q

E. coli

a) Bacterial features (5)
b) What determines pathogenicity

A

a)
- gram negative rods
- lactose fermenting
- O antigen determines serogroup
- H antigen determines serotype
- K antigen refers to capsule or pili

b)
- normal part of gut flora, but are also pathogenic
- acquisition of genes (horizontal gene transfer, DNA rearrangements, point mutations)

50
Q

E. coli

Main types of pathogenic E. coli (3)

A
  • Enterotoxigenic (ETEC)
  • Enterohaemorrhagic (EHEC or VTEC: verocytoxin-producing)
  • Uropathogenic (UPEC)
51
Q

E. coli

ETEC
a) Disease caused
b) Toxin mechanisms

A

a)
- Diarrhoea, especially in young animals
- Can cause septicaemic disease

b)
- labile toxin (LT): an AB5 type toxin (B subunits bind to surface gangliosides and mediate A subunit translocation. A subunit ADP-ribosylates αs subunit of G protein, so it is always active, so excessive cAMP production and altered ion transport
- stable toxin (ST)

52
Q

E. coli

ETEC in young farm animals
a) Source of infection and protection
b) Septicaemic colibacillosis
c) Enteric colibacillosis

A

a)
- animals usually 1-10 days old
- source from infected faeces
- lack of circulating immunoglobulins predisposing factor
- colostrum protects

b)
- most prominent in newborn lambs and foals, causing acute illness with high mortality
- bacteria invades tissues and reaches systemic circulation, clinical signs due to endotoxin
- strains are resistant to complement lysis due to surface structures

c)
- most common in 3-10 day old calves and piglets
- LT and ST involved in pathogenesis
- fluid secretion leads to death by acidosis, electrolyte imbalance and dehydration

53
Q

E. coli

EHEC/EPEC
a) Attachment/effacement
b) Toxin production

A

a)
- LEE pathogenicity island needed for virulence
- pedestal formation for attachment (cytoskeletal rearrangement)

b)
- produces large amounts of shiga-like toxin (SLT)
- AB5 toxin that inactivates 60s subunit of host cell ribosome and stops protein synthesis
- toxins act locally in gut and systemically (kidney, brain)

54
Q

E. coli

EHEC
a) Foodborne disease
b) Oedema disease in pigs

A

a)
- O157:H7 is most common cause of severe disease in humans
- Part of normal flora in bovines, can infect humans through undercooked beef, unpasteurised dairy products, and vegetables/fruit

b)
- Mainly occurs in pigs between 6 and 14 weeks old, due to SLT becoming systemic
- Neurological clinical signs (incoordination of hind legs, tremors, paralysis)
- Oedema of eyelids visisble, and at necroscopy oedema of elbow, hock joints, stomach wall, larynx and colonic mesentery

55
Q

E. coli

UPEC
a) Adhesion
b) Disease caused

A

a)
- Infection begins in colon, disruption of normal vaginal flora opens way for colonisation of vaginal tract
- urinary flow counteracts adherence, so adhesins developed (P-pili, which attach to globobiose, coded for in pap operon)

b)
- Cytotoxic toxins cause damage and inflammation
- Cause urinary tract infections
- Can cause severe disease like pyelonephritis

56
Q

Campylobacter

Bacterial features (7)

A
  • Gram negative
  • Spiral
  • Motile
  • Nonsaccharolytic
  • Non spore-forming
  • Microaerophilic
  • Growth between 32-45C
57
Q

Cambylocater

C. jejuni in chickens

A
  • High prevalence (up to 10 billion bacteria per gram)
  • Despite this, colonisation of the intestinal tract is commensal and has little or no pathology (no cellular attachment or invasion)
  • Chicken mucus inhibits campylobacter from interacting with epithelial cell surfaces
  • Infection in intensively raised, fast growing chickens can elicit a strong inflammatory response, leading to diarrhoea
  • Infection seen 2-3 weeks after chicks enter broiler shed: may be due to physiological changes in intestinal tract, or decline of maternal antibodies
58
Q

Campylobacter

a) In cats and dogs
b) In squamates
c) In cattle

A

a)
- Usually subclinical infections
- Can cause non-specific enteric clinical signs (diarrhoea etc)
- Public health concern as faeces and can shed infection, especially to young children or immunocompromised

b)
- potential reservoir and source of transmission to humans through handling

c)
- faeces can contain campylobacter in healthy animals, shedding intermittently for months
- milk can be indirectly infected
- C. fetus subsp Venerealis causes bovine venereal campylobacteriosis (BVC): major cause of abortion and infertility, sexually transmitted disease

59
Q

Campylobacter

a) In sheep and goats
b) In pigs

A

a)
- commonly found in faeces
- C. jejuni associated with diarrhoea in weaning lambs (stress)
- C. fetus subsp fetus can cause abortion

b)
- C. coli and C. jejuni are common commensals
- Infection can cause diarrhoea in piglets
- C. hyointestinalis can cause proliferative enteritis

60
Q

Campylobacter

a) Culture conditions
b) Appearance of colonies
c) Genotyping methods

A

a)
- microaerophilic or anaerobic environemnt required
- 42C for C. jejuni, 37C for other species

b)
- fresh medium produces grey, flat, irregular colonies
- reduced moisture content causes colonies to become round and convex
- does not stain well with safranin

c)
- MLST (multi locus sequence typing)
- WGS (Whole genome sequencing)

61
Q

Salmonella

Features of salmonella (5)

A
  • Gram negative rods
  • faculative anaerobes
  • motile
  • non lactose-fermenting
  • faculative intracellular pathogens
62
Q

Salmonella

Fowl typhoid
a) Causative agent
b) Transmission
c) Clinical signs
d) Post-mortem signs

A

a) S. gallinarum
b) Ingestion of infected droppings, occasionally egg transmission. Mostly affecting adult birds
c)
- watery mucoid yellow diarrhoea
- lower food intake, egg production
- increased mortality

d)
- jaundice, dark skeletal muscles
- dark red friable liver, dark spleen
- enteritis with viscous, slimy, bile stained material
- necrotic foci in pancreas

63
Q

Salmonella

Pullorum disease (bacillary white diarrhoea)
a) Causative agent
b) Clinical signs
c) Post-mortem signs

A

a) S. pullorum (mainly egg transmitted, occuring in day old chicks)
b)
- high numbers of dead-in-shell chicks, death shortly after hatching, high mortality
- anorexia, white viscous droppings

c)
- peritonitis with inflamed yolk sacs
- dark enlarged liver with surface haemorrhage and necrosis

64
Q

Salmonella

Food borne pathogen species
a) From pork and beef (1)
b) From poultry (2)

A

a)
- S. typhymurium (DT 104 primarily associated with cattle, MDR)

b)
- S. enteritidis
- S. typhymurium

65
Q

Leptospira

a) Bacterial features
b) Species in cattle
c) Species in dogs
d) Species in rats

A

a)
- thin spiral organism
- persist in humid environments
- transmitted through mucous membranes or damaged skin via contact with urine
- localise in kidney tubules, liver and spleen

b)
- L. hardjo: cause milk drop syndrome, abortion

c)
- L. canicola and L. icterohaemorrhagiae: cause kidney failure or liver disease

d)
- L. icterohaemorrhagiae: reservoir for infection (zoonotic)

66
Q

Brucella

a) Bacterial features
b) Clinical signs in animals
c) Infection in humans

A

a)
- Gram negative coccobacilli
- intracellular pathogens, persist in macrophages

b)
- transmitted by ingestion, penetration of skin and conjunctiva
- abortion
- orchitis and epididymitis
- synovitis and arthritis

c)
- acquired through raw milk, cheese, handling of infected animals
- range of clinical signs from asymptomatic, acute infection or chronic-relapsing

67
Q

Dermatophila

D. congolensis
a) Infection in cattle
b) Infection in sheep
c) Infection in humans

A

a)
- small papules covered in a progressively thicker hard crust

b)
- lesions on ears and muzzle
- wool fibres matted together by exudate

c)
- pustules on hands and feet

68
Q

Erysipelothrix

E. rhusiopathiae
a) Bacterial features
b) Disease in pigs
c) Disease in other species

A

a)
- Gram positive bacillus
- Mainly oral transmission

b)
- Acute septicaemic form: fever, anorexia, skin lesions
- Urticarial form: diamond skin disease
- Vegetative endocarditis
- Arthritis and synovitis

c)
- Turkey and gees: septicaemia, vegetative endocarditis, skin lesions
- Sheep: polyarthritis, post-dipping lameness
- Humans: erysipeloid (skin infection)

69
Q

Listeria

a) Bacterial features
b) Main species associated with disease (2)
c) Infection of animals
d) Infection of humans

A

a)
- Gram positive rods
- Widespread in environment
- Transmission through oral route

b)
- L. monocytogenes
- L. ivanovii

c)
- visceral listeriosis
- neural listeriosis (brain abcess, perivascular inflammation, facial paralysis, circling disease)
- abortion

d)
- ingestion of raw vegetables, milk, fresh cheese, meat
- bacteraemia
- meningitis
- abortion, stillbirth

PID (3 decks)

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