Exam 3 Flashcards
Are staph motile? what color is there colony morphology and what hemolysis result do they show on BA
non motile, white/ creamy, variable beta hemolysis
What staph organisms are resistant to novobiocin, which ones are susceptible
R- saphrophyticus
S-epidermidis, hominis, lugdunensis
What does it mean to be a persistent carrier? intermittent? non-carrier?
a single strain of staph over a long time
multiple strains over a long time
no strains
What environments (in society) are staph often found in
gyms, prisons, dormitories, educational settings, military, opioid crisis
What are staph the leading cause of infection for?
US healthcare facilities
MRSA rates have ___ but MSSA rates are _______
Methicillin resistant staph aureus- dropped
Methicillin susceptible staph aureus-increasing
What color does staphylococcus aureus have on a chocolate plate? and BA?
choc- gold pigment
BA- beta hemolytic, white
Math how alpha, beta, gamma and sigma hemolysin virulence factors in staph affect their pathogenicity
- lysing RBCs, damage to macros and platelets, tissue damage
- hot-cold lysin, affects sphingomyelinase in plasma membrane of RBCs
- exotoxin PVL that kills WBCs and suppresses phagocytosis
- staph a and others, not as toxic as alpha and beta
alpha-lysing RBCs, damage to macros and platelets, tissue damage
beta- hot-cold lysin, affects sphingomyelinase in plasma membrane of RBCs
gamma- exotoxin PVL that kills WBCs and suppresses phagocytosis
sigma- staph a and others, not as toxic as alpha and beta
Match the virulence factors to their functions: capsule, lipase, hyaluronidase, peptidoglycan, protease, protein A, coagulase
-prevents phagocytosis and opsonization
capable of destroying tissue
binds to Fc region of IgG
cell survival and inactivates complement IL-1 chemotaxis
enzyme hydrolyzes hyaluronic acid
acts on lipase present on surface off skin
helps prevent phagocytosis
capsule-prevents phagocytosis and opsonization
protease-capable of destroying tissue
Protein A-binds to Fc region of IgG
peptidoglycan-cell survival and inactivates complement IL-1 —-chemotaxis
Hyaluronidase-enzyme hydrolyzes hyaluronic acid
lipase-acts on lipids present on surface off skin
coagulase-helps prevent phagocytosis
What causes
toxic shock syndrome, scalded skin syndrome, folliculitis, impetigo, furuncles, carbuncles, toxic epidermal necrolysis, food poisoning, bacteremia/ sepsis, pneumonia, osteomyelitis
staph aureus
What virulence factor aids in toxic shock syndrome, what causes it
enterotoxin F, tampons
What virulence factors aid staph aureus in scalded skin syndrome
exfoliative toxins- epidermolytic toxins
Match the condition to the description: folliculitis, furuncles, carbuncles, bullous impetigo
- large pustules, highly contagious
- cluster of boils, invasive lesions
- mild inflammation of hair follicle or gland
- large raised boil
-bullous impetigo-large pustules, highly contagious
-carbuncles-cluster of boils, invasive lesions
folliculitis-mild inflammation of hair follicle or gland
furuncles-large raised boil
What virulence factors aid S. aureus in causing food poisoning?
enterotoxins A, D and B
What is the most common coagulase negative staph species
epidermidis
What illness is staph saprophyticus likely to cause
UTIs in young women, concern in pregnancy
What are the results of a coagulase test free and bound if the organism is staph lugdunensis
tube/ free- negative
slide/ bound- positive
What illness is staph lugdunensis known for? what other characteristics distinguish it
endocarditis, aggressive, high mortality rate
might have mecA gene- oxacillin resistant
What test distinguishes staph lugdunensis?
oxacillin resistance-mecA gene
Which staph species is known for vancomycin resistance
staph haemolyticus
What characteristics can distinguish micrococcus from staphylococcus
staph- glucose fermenters
micrococcus- non glucose fermenters, TETRAD formation, MOTILE
What organisms grow on MacConkey? Which ones do not.
does grow GNR
does not grow GPO
What plates will GPC grow on? What plates won’t it grow on
will grow- chocolate and BA
will not grow- MacConkey
If there is a sample from a sterile body fluid, which staph species could it be, what test can be used to confirm its presence
S. lugdunensis
PYR +
What test helps ID MRSA
Chrom agar-if pink its MRSA
cefoxitin inhibits MSSA
What conditions could cause a false positive on a catalase test
if RBCS from BAP are transmitted
Describe bound vs free coagulase, which one is more convenient?
bound-slide- more convenient
free-tube
What causes false positives in bound coagulase
bound- GNR, intermedius, saphrophyticus, haemolyticus, hominis
free coagulase-lungunensis, schleiferi
What organism is associated with dog bite wounds
staph aureus and other staph
Where in the body are strep and enterococcus normally found
pharynx, mouth, lower GI tract and vagina
Where do most strep and enterococcus cause opportunistic infection
in the respiratory system or sterile body fluids
What strep and enterococcus are almost always pathogenic?
Strep pyogenes
Strep pneumonia
Enterococcus
What is the colony morphology for strep and enterococcus
small pinpoint GPC in pairs or chains
What is the first way to differenciate strep and enterococcus species after finding GPC catalase negative
blood agar hemolysis
What hemolysis are the following strep and enterococcus
- pyogenic
- lactococcus
- enterococcus
- viridians
- pyogenic- beta
- lactococcus- gamma
- enterococcus-gamma/ alpha
- viridians- could be alpha, beta, gamma
What are lactococcus associated with
dairy products
How does lancefield grouping help categorize GPC catalase neg
detects surface antigens, proteins and carbs
Name the lancefield grouping
A,B,C,D,F,G,L
A- s. pyogenes
B- S. equi and dysgalactiae
D- enterococcus faecalis, faecium, and strep bovis
F,G,L- strep anginosus
Where are enterococcus found in normal conditions
GI tract, oral, skin
What illness do enterococcus cause
hospital acquired infections,
immunocompromised
bacteremia, endocarditis, UTIs
What are the characteristics of Strep and enterococcus cell wall
carbohydrates in cell wall helpful for lancefield classification
Lancefield classification is only for ___ hemolytic strep
beta
What does the term pyogenic mean? What are the pyogenic, and non pyogenic strep
fever inducing
pyogenic-beta Group A, B, C, F, G
non pyogenic- gamma and alpha- non beta
Alpha hemolytic ______ lysis
Beta hemolytic _______lysis
Gamma hemolytic _____ lysis
partial
complete
no hemolysis
What do strep pyogenes look like on BA
beta, small pinpoint grey
Where are strep pyogenes capable of causing infection and how are they transmitted
skin, upper respiratory,
transmitted person to person- direct
aerosolized from cough, fomites or sneezes- indirect
Match the virulence factors to the effects they cause: protein F, hyaluronic acid, M protein, strep O S Dnase hyaluronidase, SPEs, C5a
- destroys complement
- produce rash
- produces enzymes that help invade and destroy tissues
- antiphagocytic
- inhibits phagocytosis
- aids in epithelial cell attachment-fibronectin
- destroys complement- C5a peptidase
- produce rash- SPEs
- produces enzymes that help invade and destroy tissues- strep O S Dnase hyaluronidase
- antiphagocytic- M protein
- inhibits phagocytosis- hyaluronic
- aids in epithelial cell attachment-fibronectin- protein F
What organism causes these diseases
cellulitis, scarlet fever, myositis, sepsis, pneumonia, step toxic shock, strep throat, pyodermal infection, necrotizing fascitis, Rheumatic fever, glomerulonephritis
Strep pyogenes
What treatment is used against Strep pyogenes
penicillin, erythromycin
What virulence factors do strep pyogenes have in terms of toxins
strep O- oxygen unstable, immunogenic
strep S- oxygen stable, non immunogenic
Match the virulence factors to the disease: SPEs, exotoxins, M protein,
Toxic shock syndrome
Rheumatic fever
Pyodermal infection-scarlet fever
Toxic shock syndrome- SPEs
Rheumatic fever- M protein
Pyodermal infection-scarlet fever- exotoxins
Name the PYR results for
Strep pyogenes
viridians
enterococcus
Strep pyogenes: PYR +
viridians: PYR -
enterococcus PYR +
Which strep species is a type of viridian strep
anginosus
Name the LAP results for viridians strep Aerococcus viridans enterococcus lactococcus
viridians strep LAP +
Aerococcus viridans LAP -
enterococcus LAP +
lactococcus +
