I: Staph and Strep Flashcards
____-hemolytic strep: blood agar appears normal
Gamma (No)
____-hemolytic strep: clear zone of medium surrounding colonies on blood agar
Beta (Complete)
____-hemolytic strep: green coloration of medium surrounding colonies on blood agar.
Alpha (Incomplete)
___-antibodies signal previous strep infection.
ASO
Acute rheumatic fever typically occurs ____ weeks after infection.
2 to 4
ARF or PSGN? Common recurrence with reinfection
ARF
ARF or PSGN? Rare in infants, elderly
ARF
ARF or PSGN? Summer Predominance
PSGN
ARF or PSGN? Winter-Spring Predominance
ARF
Group D ______ are resistant to penicillins
enterococci
Late GBC infections are frequently caused by type __ GBS.
III
Most neonatal GBS infections involve type __ GBS.
II
Name 4 extracellular products of group A strep species
Streptolysin O, Streptolysin S, Pyrogenic Exotoxins, Spreading Factors
Name 4 lab/radiologic features of necrotizing fasciitis.
leukocytosis with right shift, elevated creatine kinase, elevated creatinine, SQ and fascial edema on imaging
Name 4 spreading factors secreted by group A strep species.
Hyaluronidase, streptokinase, DNAase, proteinase
Name 5 antigens seen in strep species.
M protein, R protein, T protein, Lipoteichoic acids (LTAs), Hyaluronic acid capsule
Name the most common species implicated in bacterial endocarditis
viridans strep
Name the most common species implicated in dental caries.
Strep mutans
Name the syndromes seen in indivdiuals susceptible to exfoliatins in the newborn, infant, and pediatric age groups.
Ritter’s Disease, Scalded Skin Syndrome, Staph scarlet fever
Name the two most common pathogens in cellulitis?
Staph aureus, Group A strep
Name two extracellular products of group B strep species
Neuraminidase, CAMP factor
PSGN typically occurs ____ weeks after infection.
3 to 6
Staphylococci organize in ____.
pairs or clusters
Streptococci are gram-____ cocci that are catalase-_____.
Positive; Negative
Streptococci organize in ____.
chains
What is the gold standard diagnosis for necrotizing fasciitis?
Surgical biopsy and exploration
What is the most common cause of acute endocarditis?
Staph aureus
What is the most common cause of bacterial pharyngitis?
Group A Strep
What is the most common cause of prosthetic valve endocarditis?
Coag-negative staph
What is the most common cause of subacute endocarditis?
Strep viridans
What is the most common etiology of necrotizing fasciitis?
Streptococcus pyogenes
What virulence factor mediates the pathogenicity of scarlet fever?
Pyrogenic Exotoxins
Which age group is particularly susceptible to group B strep infection?
Newborns
Which diagnosis? Erythroderma, organ failure, fever, rash with desquamation, hypotension
Toxic Shock Syndrome
Which diagnosis? Painful erythroderma, Nikolsky sign, bullous impetigo
Scalded Skin Syndrome
Which extracellular product? Enhance host susceptibility to endotoxin shock, immunosuppressive effects, secreted by group A strep species
Pyrogenic Exotoxins
Which extracellular product? Oxygen-labile hemolysin seen in group A strep species
Streptolysin O
Which extracellular product? Oxygen-stabile hemolysin that can be cytotoxic to leukocytes and RBCs
Streptolysin S
Which infection? Fever, diffuse red rash, coated strawberry tongue
Scarlet Fever/Group A strep
Which Lancefield Group? Bacitracin-Sensitive and M-antigen
A
Which Lancefield Group? Bile Esculin Hydrolysis Positive and 6.5% NaCl Tolerance
D Enterococcus
Which Lancefield Group? Bile-Esculin Hydrolysis Positive
D
Which Lancefield Group? Capsular polysaccharide
Strep pneumoniae
Which Lancefield Group? Positive CAMP test
B
Which of the following media can grow staphylococci? Blood, Chocolate, MacConkey
Blood, Chocolate
Which sign of endocarditis? Non-tender, flat macular lesions on digits
Janeway lesions
Which sign of endocarditis? Retinal hemorrhages
Roth spots
Which sign of endocarditis? Tender, purple raised papules on digits
Osler nodes
Which skin infection? Irregular border with fever and leukocytosis possible
Cellulitis
Which skin infection? Pain out of proportion to physical exam, bullae later in progression
Necrotizing Fasciitis
Which skin infection? Well demarcated borders, not usually seen in lower extremities
Erysipelas
Which skin infections are commonly caused by Group A strep?
Impetigo, Cellulitis
Which staph aureus virulence factor? Associated with Toxic Shock Syndrome
Enterotoxin B and C
Which staph aureus virulence factor? Binds Fc receptor to prevent antibody-mediated phagocytosis.
Protein A
Which staph aureus virulence factor? Binds fibrinogen to convert it to fibrin and prevent phagocytosis
Clumping Factor
Which staph aureus virulence factor? Binds to glycolipids to cause separation at granular cell layer desmosomes in the skin
Exfoliatin A and B
Which staph aureus virulence factor? Causes white cell lysis and protects from phagocytosis, causes severe invasive disease
Leucocidin
Which staph aureus virulence factor? Clots plasma to wall off infection as an abscess
Coagulase
Which staph aureus virulence factor? Extracellular matrix that cements and protects
Slime
Which staph aureus virulence factor? Implicated in Scalded Skin Syndrome
Exfoliatin A and B
Which staph aureus virulence factor? Preformed toxin in food that causes GI disturbance (most common cause of food poisoning)
Enterotoxin
Which staph aureus virulence factor? Superantigen that stimulates cytokines and causes endothelial leakage
Toxic Shock Syndrome Toxin 1 (TSST-1)
Which staph species is associated with shunt and indwelling line infections?
Epidermidis
Which staph species is associated with UTI?
Saphrophyticus
Which strep species displays M protein?
Streptococcus pyogenes
Which type of necrotizing fasciitis? Caused by strep pyogenes in patients of any age with no risk factors
II
Which type of necrotizing fasciitis? Mixed bacterial infection in patients with risk factors (recent surgery, diabetes, vascular disease)
I
