5. Strep and Staph (Emily) Flashcards
Streptococcus is a gram-________ cocci
Positive
Why does strep require the addition of blood or serum to media for growth?
It’s susceptible to desiccation
Which type of streptococci tend to be the most pathogenic to animals?**
B-hemolytic
Most pathogenic strep species are ________ associated with _______ ________ and _________
Pyogenic; abscess formation; suppuration
How can commensals and opportunistic pathogens be identified on a blood agar plate?
Oxidation of iron in blood agar makes it greenish
How can non-pathogenic bacteria be identified on a blood agar plate?
No hemolysis will be seen
How can pathogenic bacteria be identified on a blood agar plate?
Zone of inhibition (hemolysis) around colony
What is a common condition in cows caused by several strep species?
Mastitis
What is an important strep species in dogs and cats?
S. canis
What are some key virulence factors that vary by strep species?
-Exotoxins
-Capsular polysaccharide
-Hemolysins
-CAMP factor
-M-protein
-Streptokinase
Which species commonly cause mastitis in bovines?
-Strep. agalactiae
-Staphylococcus aureus
-Strep. dysgalactiae
-Strep. uberis
-Klebsiella species
-E.coli
Which bovine mastitis species are contagious?
S. agalactiae
Staph. aureus
Which bovine mastitis species are contagious and environmental?
Strep. dysgalactiae
Strep. uberis
Which bovine mastitis species are environmental?
Klebsiella
E.coli
What test can be done for a somatic cell count?
California mastitis test (CMT)
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)
What are important aspects of Strep. agalactiae in mastitis?
-Contagious
-Subclinical (high SCC and reduced milk production)
What is the most important for persistence with Strep. agalactiae?
Type 3 Capsular Polysaccharide —> prevents C3 opsonization
What are 4 Step. agalactiae toxins?
-Sphingomyelinase
-Neuramindase
-Hemolysin
-Lipoteichoic acid
What are important aspects of Strep. uberis in mastitis?
-Environmental
-Causes clinical mastitis (severity depends on strain and number of organisms)
What is the major difference between Strep. dysgalactiae subspecies dysgalactiae and subspecies equisimilis?
Subsp dysgalactiae: alpha-hemolytic
Subsp equisimilis: B-hemolytic
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
