Mastitis Flashcards
How is mastitis categorised?
What are the differences and similarities
Into subclinical mastitis where an infection is present but there are no visible clinical signs but changes in somatic cell count, milk quality and yield. OR
Clinical mastitis where there is changes in milk, udder and cow. Clinical mastitis is graded
Similarities = intramammary infection
Differences =
CM exhibit symptoms, SC detected by lab with inc somatic cell count
What is mastitis grading
Grade 1 - mild changes in milk
Grade 2A - acute changes in milk. Udder hot and painful
Grade 2C - Chronic changes in milk. Udder hard and lumpy
Grade 3 - Changes in milk and udder. Cow SICK
What is somatic cell count?
What do we want?
n.o cells per ml of milk; mainly epithelial and WBC; presence of infection increases the latter hugely
“high” SCC
400,000 cells/ml. Want under 200,000 cells
what categories are mastitis pathogens?
Contagious or
Environmental
Talk about contagious mastitis pathogens
- source
- how spread
• Obligate parasites = must live on cow to survive
Obligate parasites. Located udder skin, teat skin, intra-mammary, tonsils, vagina
• Main source = is other infected cows e.g. milking cleaning products
• Spread from cow to cow during milking via fomites : cluster, milker’s hands, communal teat cloth, teat brushes
Talk about environmental pathogens
- what is the key risk period xxxx
- Live in slurry, bedding, soil, feed and water
* Infection between milking times and during milking
List the main contagious mastitis pathogens
- Staphylococcus aureus
- Streptococcus dysgalactaie
- Streptococcus agalactiae
- Coagulase negative Staph. spp.
- Mycoplasma spp.
- Contagious cow adapted strains of Streptococcus uberis (note just strep uberis on its own isn’t)
You will isolate others from mastitis cases : look them up e.g. Veterinary Medicine (Radostits etc ) and consult with diagnostic laboratory
There are undoubtedly pathogens we don’t know about yet (microbiome work)
List main environmental mastitis pathogens
- Streptococcus uberis
- Coliforms e.g. Escherichia coli, Klebsiella pneumoniae
- Yeasts/fungi
- Summer Mastitis (a syndrome; see later in lecture; multiple bacteria)
You will isolate others from mastitis cases : look them up e.g. Veterinary Medicine (Radostits etc ) and consult with diagnostic laboratory
There are undoubtedly pathogens we don’t know about yet (microbiome work)
What are the 2 methods of identifying organism causing mastitis?
- Culture
2. PCRs
Pros and cons of Culturing mastitis for bacterial ID
Grow the bacteria
Bacteria must be alive;
No antibiotics for at least 7 days prior to culture;
Must be shedding on the day of sampling (which is luck!).
If you happen sample on a non-shedding day your result will be NEGATIVE for Staph. aureus
Pros and cons of PCR mastitis for bacterial ID
Detects bacterial DNA
BActeria can be Dead or alive;
Can be done Before/during/after antibiotics
The PCR is set up for the common pathogens DNA and the beta-lactamase gene;
So if it’s another bug not on the list ….it won’t be found!
Why could a sample results fail?
Contamination Testing panel Not shedding Poor storage/handling Unknown pathogen Fastidious
What is the most common contagious pathogen for mastitis? and what is its source of infection?
Staphylococcus aureus
cows and fomites
Spread amongst heifers pre-calving by teat sucking
Fly spread
What type of bacteria is Staphylococcus aureus?
How does it appear on blood agar?
Gram positive cocci
Coagulase positive
On blood agar, white colonies with a ring of haemolysis
What makes staphylococcus aureus difficult to culture?
What makes SA difficuly to treat?
- Intracellular - survives in the cells and may not be detected unless cells are broken open by freezing the milk.
- Biofilms - Survives in biofilms (mixture of cells, extracellular material and bacteria) which protects the bacteria
Dtt:
1. Antibiotic is poorly accessible
- Often responsible for recurrent persistent chronic infections/persistently high cell counts; may be lifelong
