Strep/Enterococcus

Question 1

Streptococci

Answer 1

catalase-negative, gram positive cocci

Question 2

Strep canis

Answer 2

Lancefield C, beta hemolytic. Most common. Dogs, cats natural hosts. Primary cayses of strep toxic shock syndrome, nec fascitis

Question 3

S. equi subsp. zooepidemicus

Answer 3

Lancefiled C, beta hemolytic. Pneumonia, sinusitis in grouped animals primarily. Also associated with meningitis.

Question 4

S. dysgalactiae

Answer 4

Lancefield C, beta hemolytic. Uncommon. Isolated from dogs with septicemia, dermatits, pneumonia.

Question 5

S.bovis group

Answer 5

Lancefield D, alpha or gamma. Uncommon. Isolated from dogs with UTI, endocarditis.

Question 6

S. agalactiae

Answer 6

Lancefield B. Beta or gamma. Rare. Isolated from dogs, cats with endocarditis, neonatal septicemia.

Question 7

Mechanism of STSS

Answer 7

Can also be causes by staph. MOA-elaboration of pyrogenic exotoxins by strep, which act as superantigen. Superantigen stimulate T cell receptors by binding to MHC class II - bypasses normal MHC restricted antigen processing. Leads to sudden and massive cascade of cytokine release.

Question 8

Nec Fas

Answer 8

Begins as minor wound. Rapid progression over 24-72 hours. “Flesh-eating bacteria”. Virulence factor- a protein analogous to M protein, a major virulence facor of S. pyogenes, has been identified in S. canis. M protein has important antiphagocytic properties.

Question 9

Enterococcus spp.

Answer 9

Alpha or non-hemolytic gram positive bacteria. Usually lancefield D antigens. Usualy commensals of GI tract. Imp nosocomial pathogen.

Question 10

Enterococcus spp. Tx.

Answer 10

Often resistant to wide variety of diff antimicrobial drug class. Intrinsic resistance to b-lactams b/c possess low-affinity penicillin binding proteins. Low level intrinsice resistance to aminoglycosides (results from decreased drug uptake). Uptake is enhanced when enterococci are exposed to beta lactams. Resistant to TMS (enterococci exogenously acquire folate).

Question 11

E. faecium strain SF68

Answer 11

Investigated as probiotic in dogs, cats -mixed results. Some studies suggest that supplementation of food with this probiotic stimulate local and systemic immune function.

Question 12

Enterococcus spp. UTI

Answer 12

Development of enterococcus UTI may be promoted by repeated use of Abx to treat recurrent UTIs. When present with other bacteria, especially in urinary tract, treatment of other bacteria may be sufficient to resolve infection.

Question 13

Streptococcal endocarditis

Answer 13

more likely to have cocurrent poyarthritis than other causes of endocarditis

Question 14

Strep Drugs

Answer 14

1) Pen g - with clindamycin for nec fasc or myositis. 2) Ampicillin - combine with gentamicin for s. equi subspecies zooep - due to synergism. 3) Amoxi. 4) Cefazolin. 5) Cephalexin. 6) TMS - for strep meningitis

Question 15

Enterococcus spp. Drugs

Answer 15

1) Ampicillin/Amoxi - consider with gentamicin - syngergistic compound. 2)Vancomycin/linezolid/nitrofurantoin - in patients with high-level aminoglycoside resistance. 3) Chloramphenicol