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20 Cards in this Set
- Front
- Back
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Two main groups of Gram POS cocci
(and examples) |
Catalase Positive (Staphylococcus, Micrococcus, and Rothia)
Catalase Negative (Streptococcus, Enterococcus, Gemella, Globicatella, Helococcus, and Vagococcus) |
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What is Catalase?
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Enzyme in an organism which INACTIVES H2O2 thus allowing it to survive within the cell.
Drop Catalase onto bacteria - if POS it will Instantaneously effervesce |
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Morphology of Staphylococci
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Gram POS cocci in clusters/pairs, and occasionally appear to be in short chains (though they aren't really... especially if you see a long chain...it isn't really a long chain)
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What is Coagulase?
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Clumping Factor
A cell bound or free - Binds to Prothrombin and catalyzes Fibrinogen --> Fibrin. |
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How is the Coagulase test run and what does it indicate?
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Drop Rabbit plasma on bacteria. If they clump it up - POSITIVE
Positive --> Bacteria in blood may form an armor of Clot! However, it is NOT True that Coag Pos = BAD, and Coag Neg = Good! |
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Which is more virulent, Coagulase POS or Coagulase Neg Staph?
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NOT AN INDICATOR, positive being worse is an old school of thought and is untrue!
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What do the following species infect?
1. S. pseudintermedius (intermedius) 2. S. aureas 3. S. hyicus 4. S. schleiferi (*2nd to intermedius) 5. S. delphini 6. S. felis 7. S. lutrae |
1. Dog, Mink, Horse, Cat
2. Cows (mastitis issue), Birds, Pets 3. Pigs, Cows 4. Dogs 5. Dolphins 6. Cats 7. Sea Otters |
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Let's think about this a different way - what Staphylococci infect:
1. Dogs 2. Cats 3. Pigs 4. Horses 5. Cows 6. Birds 7. Dolphins 8. Sea Otters |
1. intermedius, aureus, schleiferi,
2. intermedius, aureus, felis 3. hyicus, (aureus?) 4. intermedius, (aureus?) 5. hyicus, aureus 6. aureus 7. delphini 8. lutrae |
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What is the number 1 organism found in Canine pyoderma?
What else does this organism cause in dogs? |
Staphylococcus pseudeintermedius
Osteomyelitis, Arthritis, Mastitis, Otitis Externa, |
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What is the second most common Staph species affecting dogs?
What dzz is it associated with? |
S. schieferli
Otitis externa, Otitis media, pyoderma |
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What is the leading cause of bovine mastitis?
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S. aureus
Typically causes chronic infection. (there are some E. Coli, Klebsiella, and other Gram NEGs which are common - But S. aureus is the biggest deal right now) |
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What are 2 other common S. aureus Dz in ruminants?
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1. Tick pyemia in lambs. assoc with tick-borne fever due to Anaplasma phagocytophia... S. aureus enters AT TICK BITE
High Mortality 2. From an unusual ANAEROBIC S. aureus. Abscess Dz in Sheep. Large Abscesses on the back of the neck. Can be hard to ID as many people only culture Aerobically. Need to to an Anaerobic culture too! |
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How does Staph affect horses?
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S. aureus
Mastitis, pectoral abscesses, Spermatic cord abscess post castration... A MRSA is traveling through the equine world... NOT GOOD! Transmission is thought to occur from direct contact bw infected animals and people. Nasal MRSA carriage is common in horses (though not in many other animals) |
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How does Staph affect piggies?
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S. hyicus
Exudative epidermitis (Greasy Pig Dz) Occurs in young pigs. The nip each other when young, and get down on knees to suckle - Casue SKIN ABRASIONS allowing infection to occur. Thick Grey/Brown exudate. 50% Mortality in young pigs. Rapidly hits lungs, lymph, kidneys, brain. Very contagious. Economically hard-hitting. |
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How does Staph affect birds?
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S. aureus
Bumblefoot A chronic pyrogranulomatous process in the SubQ tissue of the Foot. Causes Lameness |
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Staph Virulence Factors
What are Adhesins? |
bacterial surface protein which stick to host ECM proteins.
MSCRAMM = Microbial Surface Components Recognizing Adhesive Matrix Molecules |
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Staph Virulence Factors contd...
What is the significance of a capsule? How many different capsules does S. aureus make? How are capsules made? |
Capsules are polysaccharide layers that help prevent Phagocytosis
S. aureus makes 11 different ones Genes for them found on Staphylococcal Cassette Chromosome (SCC). SCC = a Pathogenicity Island (Horizontally Transmissable mobile piece of DNA which holds information to get around host systems and thus make the bacteria more pathogenic) |
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Staph Virulence Factors contd...
How does the cell wall contribute to virulence? |
Gram POS wall has Teichoic Acid and PG which interact with M-phages --> proinflamm cytokines
Teichoic acid also increases adhesion |
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Staph Virulence Factors contd...
What is Protein A? |
Protein A (of S. aureus) binds to the Fc fragment of Igs.
Binds to Ig, attract Neutrophils, then KILL THEM! bwahahaha Interferes with immune response by interfering with opsonization and ingestion by PMNs |
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Staph Virulence Factors contd...
Enterotoxin and Pyrogenic Toxin Superantigens Hemolysins |
Exotoxins A-M include enterotoxins
Superantigen --> Cytokine Storm by nonspecifically activating T-Cells Staphy have 4 Hemolytic toxins (alpha-delta) Hemolysis is not their MO during infection - its just a diagnostic. |
