5. Strep and Staph (Emily) Flashcards by Emily Huff

Streptococcus is a gram-________ cocci

Positive

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Why does strep require the addition of blood or serum to media for growth?

It’s susceptible to desiccation

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Which type of streptococci tend to be the most pathogenic to animals?**

B-hemolytic

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Most pathogenic strep species are ________ associated with _______ ________ and _________

Pyogenic; abscess formation; suppuration

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How can commensals and opportunistic pathogens be identified on a blood agar plate?

Oxidation of iron in blood agar makes it greenish

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How can non-pathogenic bacteria be identified on a blood agar plate?

No hemolysis will be seen

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How can pathogenic bacteria be identified on a blood agar plate?

Zone of inhibition (hemolysis) around colony

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What is a common condition in cows caused by several strep species?

Mastitis

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What is an important strep species in dogs and cats?

S. canis

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What are some key virulence factors that vary by strep species?

-Exotoxins
-Capsular polysaccharide
-Hemolysins
-CAMP factor
-M-protein
-Streptokinase

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Which species commonly cause mastitis in bovines?

-Strep. agalactiae
-Staphylococcus aureus
-Strep. dysgalactiae
-Strep. uberis
-Klebsiella species
-E.coli

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Which bovine mastitis species are contagious?

S. agalactiae
Staph. aureus

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Which bovine mastitis species are contagious and environmental?

Strep. dysgalactiae
Strep. uberis

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Which bovine mastitis species are environmental?

Klebsiella
E.coli

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What test can be done for a somatic cell count?

California mastitis test (CMT)

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What is Strep. agalactiae?

-Lancefield groub B (?)
-Obligate parasite of mammary glands in cows
-Commensal in human GI tract (one strain can cause neonatal septicemia and meningitis in human fetuses though)

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What are important aspects of Strep. agalactiae in mastitis?

-Contagious
-Subclinical (high SCC and reduced milk production)

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What is the most important for persistence with Strep. agalactiae?

Type 3 Capsular Polysaccharide —> prevents C3 opsonization

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What are 4 Step. agalactiae toxins?

-Sphingomyelinase
-Neuramindase
-Hemolysin
-Lipoteichoic acid

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What are important aspects of Strep. uberis in mastitis?

-Environmental
-Causes clinical mastitis (severity depends on strain and number of organisms)

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What is the major difference between Strep. dysgalactiae subspecies dysgalactiae and subspecies equisimilis?

Subsp dysgalactiae: alpha-hemolytic

Subsp equisimilis: B-hemolytic

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What are important aspects of Strep. dysgalactiae in mastitis?

-Contagious AND environmental
-Acute and clinical mastitis thats associated with injury to teat/udder epithelium

Strep. dysgalactiae subsp equisimilis is not ________

Zoonotic

Important aspects of Strep. suis

-Most commonly affects pigs (carried in tonsils and spreads via resp secretions)
-Serotype 2 is most pathogenic for humans and pigs
-ZOONOTIC!

What are 2 virulence factors in Strep. suis?

-Capsular polysaccharide (blocks C3 opsonization) -Suilysin (creates holes in target cell membranes)

What can Strep. suis cause in humans?

-Sepsis -Meningitis -Hearing loss -Renal failure -Endocarditis -Pneumonia

Important aspects of Strep. equi subsp equi

-Strangles!! -Very contagious -Does not affect other species -Adhesins: SeM to epithelium of tonsils

Pus is made of

Neutrophils

What are 2 virulence factors in Strep. equi subsp equi?

-Hyaluronic acid capsule (prevents phagocytosis) -M-protein (antiphagocytic)

What are some complications of strangles?

-Guttural pouch disease -Persistent carriers -Metastatic abscessation (bastard strangles) -Purpura hemorrhagica

Metastatic abscessation can affect ________________

Any organ system

Important aspects of Strep. equi subsp zooepidemicus

-Commensal and opportunistic pathogen -ZOONOTIC! -Primarily affects horses and pigs

What is an important virulence factor with Strep. equi subsp zooepidemicus?

Protease that promotes invasion and destruction of host tissue ---> necrosis

Important aspects of Strep. canis

-B-hemolytic -Opportunistic pathogen -Causes neonatal septicemia in kittens

Most important aspects of Strep?***

-Gram-positive cocci -Facultative anaerobes -Pus/abscesses -Blocks phagocytosis -Hemolysins -Some are zoonotic

Genus characteristics of Staphylococcus?

-Gram-positive cocci -Major component of normal microflora of animals and humans -Facultative anaerobes

Which 3 Staph species are of veterinary importance?

-Staph. aureus -Staph. pseudintermedius -Staph. hyicus

What are 4 key virulence factors best characterized by Staph. aureus?

-Coagulase -Enterotoxins (food poisoning) -Exfoliatins (skin damage) -Hemolysins (lysis of RBCs)

Important aspects of Staph pathogenicity

-Pyogenic bacteria -Produce suppurative lesions -More virulent strains can be invasive and cause bacteremia and hematogenous spread to new body sites

What is the most significant virulence factor of Staph and what does it cause?

Coagulase. Causes plasma coagulation

Which 2 species of Staph are coagulase-positive?

Staph. aureus Staph. pseudintermedius

A bacteria that contains alpha and beta hemolysins will cause what to appear on a blood agar plate?

A double zone of hemolysis

Which 2 species of Staph produce both alpha and beta hemolysins?

Staph. aureus Staph. pseudintermedius

What are 4 mechanisms of innate immune resistance in Staph. aureus?

-gamma-hemolysin -Clumping factor -Protein A -Catalase

Important aspects of Staph. aureus in mastitis

-Chronic and contagious -Causes subclinical mastitis -Gangrenous (necrotizing) mastitis

Important aspects of Staph. aureus in poultry

-Causes arthritis, synovitis, chondronecrosis osteomyelitis -Gangrenous dermatitis -Omphalitis -BUMBLE FOOT* (pododermatitis)

What does Staph. aureus cause in horses?

Neonatal septicemia and secondary infections (wound/surgical site infections)

Important aspects of Staph. hyicus in pigs?

-Commensal of pig skin -Exudative epidermitis (greasy pig disease) -Contamination of damaged skin with exfoliative toxin will cause epidermal necrolysis

What are 3 important virulence factors with Staph. hyicus?

-Exotoxins (exfoliation and epidermitis) -Adhesins (fibronectin-binding proteins) -Capsular polysaccharides and Protein A (block phagocytosis)

Important aspects of Staph. pseudintermedius in dogs

-Canine skin and ear infections most common -Opportunistic infections associated with predisposing factors and secondary to underlying disease -PYODERMA

Which Staph species are methicillin resistant (MR)?

Staph. aureus (MRSA) Staph. pseudintermedius (MRSP)

What gene allows for methicillin resistence?

MecA gene -Leads to generalized resistance to beta-lactam antimicrobials -Opportunistic infections can be serious

MRSA and MRSP are _____________ between pets and humans

Transmissible

Important aspects of Staphylococcus***

-Gram-positive cocci -Facultative anaerobes -Coagulase+ = pathogenic -Opportunistic -Pus/abscesses -Neonatal septicemia (horses) -Methicillin resistance -Zoonotic species