Streptococcus & enterococcus

Question 1

Requirements to grow Streptococcus

Answer 1

• Require addition of blood or serum to culture media
• No growth in NaCl

Question 2

Morphology of streptococcus

Answer 2

gram + cocci approx 1.0um in diameter & form chains of different lengths

Question 3

Catalase test for streptococcus

Answer 3

catalase -

Question 4

type of pathogen

Answer 4

Commensal

Question 5

Describe Streptococcus

Answer 5

infect many animal species, causing suppurative conditions such as mastitis, metritis, polyarthritis & meningitis

Question 6

O2 requirement of streptococcus

Answer 6

Facultative anaerobes which are non-motile

Question 7

What is strangles

Answer 7

highly significant & infectious disease primarily affecting young horses & donkeys worldwide

Question 8

Name the infectious agent that cause strangles

Answer 8

Streptococcus equi subspecies equi

Question 9

Describe Streptococcus equi subspecies equi

Answer 9

• not commensal
• If Strep equi is found in a horse’s noses, it is highly likely that the horse either has the infection or is in the process of developing it
• highly contagious URTI in horses

Question 10

Transmission of strangles

Answer 10

Direct or indirect contact with infectious material from sick horses

Question 11

Primary sources of transmission of strangles

Answer 11

nasal secretions, pastures or water troughs contaminated with bacterium

Question 12

What contributes to environmental spread of strangles

Answer 12

Thick, yellow, purulent external infections resulting from ruptured LN are highly contaminated & contribute significantly to environmental spread

Question 13

What are carrier animals

Answer 13

Animals incubating the disease & not yet showing clinical signs can transmit the infection

Question 14

Infectious stage of strangles

Answer 14

• cover the period from initial exposure through active disease manifestation & shedding
• Exposure & initial transmission
• High horse density
• Entry & LN abscessation
• Rupture & external shedding
• Internalisation & systemic spread

Question 15

S. suis infection describe

Answer 15

• most common cause of meningitis in weaned pigs & now in growers
  
  • beyond meningitis, can lead to septicaemia can cause sudden death, carditis (vegetative lesions on the heart valves), arthritis, pneumonia

Question 16

Major capsule types of s. suis

Answer 16

• 33 serotypes
  
  • Potential for more
  • Most important are capsular
• Type 2 (high virulence)
  
  • Most pathogenic type
  • Prevalent in Aus
• Cap 2, 9 & 14: important types worldwide

Question 17

Carrier state of s. suis

Answer 17

• most pigs carry S. suis in their tonsils
  
  • not all strains are pathogenic
• Studies suggest that pathogenic strains may hide inside cells, meaning a surface swab of tonsils might not always reveal the disease-causing strains

Question 18

prevention of s. suis in humans

Answer 18

• proper hand hygiene & PPE
  
  • Crucial for individuals working with pigs or handling carcasses
• Educating people about not consuming products from sick animals: vital due to zoonotic risks

Question 19

Risk factors in S. suis

Answer 19

• pigs are raised & slaughtered under unhygienic conditions often by inexperienced backyard butchers
• close contact with ill or dead animals
• Humans getting injured while butchering or hnalding infected carcaess, leading to exposure to infected animal blood

Question 20

Zoonotic potential & spread to humans from S.suis

Answer 20

• highly effective zoonotic pathogen
  
  • Can cause severe systemic infections in humans
    
    • Fatal meningitis & septicaemia
• Outbreaks in China in 1998 & 2005
  
  • attributed ti newly emerging or hypervirulent strains such as ST 7

Question 21

Carrier animals of strangles

Answer 21

• Recovering carrier animals can also shed the bacterium for up to six weeks post-infection, even after their clinical signs have resolved
• If the infection internalises into the gutteral pouch, horses can become intermittent shedders for many months, making it very difficult to eliminate the infection

Question 22

Purpose of post mortem exam in S. suis

Answer 22

• to ID the virulent strains causing disease, it is crucial to isolate the organism from specific body sites during post-mortem examination
  • Brain, heart & joints
  • Isolation from lungs can indicate pneumonia but may also be associated with other infections

Question 23

classification method used for Streptococcus spp

Answer 23

Lancefield’s grouping (A-U)
Haemolytic patterns

Question 24

What is lancefield grouping

Answer 24

was the traditional way to classifying streptococci before the routine use of whole genome sequencing & MALDI TOF

Question 25

What is Lancefield’s grouping based on

Answer 25

antigenicity of cell wall polysaccharides

Question 26

Use of Lancefield’s grouping and efficacy of it

Answer 26

- Generally only works for pathogenic streptococci & not all Streptococcus spp fit into this grouping - Heavily used in countries with limited resources - In Aus, most labs transitioned to MALDI TOF due to speed & accuracy

Question 27

Describe Lancefield’s grouping method

Answer 27

- involves a latex agglutination test where bacterial cells are lysed to release free antigens These antigens are then mixed with latex particles coated with specific antibodies - If corresponding antigen & antibody interlock, visible agglutination occurs, indicating a + reaction

Question 28

identify the major groups of streptococci

Answer 28

1. Streptococcus pyogenes (Group A strep) 2. Streptococcus agalactiae, S. dysgalactiae, and S. uberis 3. Streptococcus equi subspecies equi, S. dysgalactiae subspecies equisimilis, and S. zooepidemicus 4. Streptococcus suis 5. Streptococcus canis (Group G streptococcus) 6. Streptococcus delphinus (Group F strep) 7. Streptococcus pneumoniae

Question 29

What is mastitis

Answer 29

Inflammation of mammary gland

Question 30

Describe Subclinical mastitis:

Answer 30

- no signs of infection - Major significance to dairy industry

Question 31

Describe Clinical mastitis

Answer 31

- inflammatory response to infection causing visibly abnormal milk (e.g. colour, fibrin clots) - As extent of the inflammation increases, changes in the udder may also be apparent (swelling, heat, pain & redness) - Acute: suppurative - Chronic: granulomatous - Gangrenous

Question 32

cost of mastitis

Answer 32

decreased milk production; treatment costs; early culling

Question 33

S. aureus & mastitis describe

Answer 33

- predominant cause of mastitis in dairy cows - Can lead to both acute & chronic forms of the disease

Question 34

S. epidermis pathogenicity

Answer 34

less negative compared to S. aureus

Question 35

S. agalactiae

Answer 35

- Contagious mastitis only - Obligate parasite of the udder - Can be eliminated with mastitis (with S. aureus) - Now virtually eradicated from most milk producing countries

Question 36

S. dysgalactiae

Answer 36

- contagious & environmental - Sporadic acute infections

Question 37

S. uberis

Answer 37

- environmental mastitis only - sporadic infectious resulting from teat trauma

Question 38

Other environmental mastitis pathogens

Answer 38

- Mud, manure, bedding material - Escherichia coli, pseudomonas aeruginosa, Klebsiella pneumoniae

Question 39

Summer mastitis pathogen

Answer 39

- Infection of predominantly dry cows - Flies transmit bacteria - Trueperella pyogenes

Question 40

Sporadic mastitis pathogen

Answer 40

mycoplasma, nocardia

Question 41

Difference of growth between Staph & strep

Answer 41

Staph: grow on basal media Strep: require enriched media

Question 42

Difference of colonial morphology between Staph & strep

Answer 42

Staph: large colonies Strep: Small pin point colonies

Question 43

Difference of Gram stain of Strep & staph

Answer 43

Staph: gram + in clusters Strep: gram + in chains

Question 44

Difference between catalase test of strep & staph

Answer 44

Staph: + Strep: -