Review Flashcards
Media:
Tryptic soy agar with 5% sheep blood. Allows differentiation of hemolysis.
SBA (sheep blood agar)
-for most nonfastidious bacteria
Media:
Chocolate agar is used for the isolation of fastidious organisms including ___________ and ____________.
Haemophilus and Neisseria
-supplies X (hemin) and V (NAD) factors. Incubate in 5% CO2
CNA agar is used for the isolation of…
Gram-positive cocci (GPC), especially from wound and stool culture
Examples of alpha-hemolytic on SBA
Streptococcus pneumoniae, viridans
streptococci, some enterococci
Examples of beta-hemolytic on SBA
Group A strep, group B strep, Listeria
monocytogenes
Example of gamma (nonhemolytic)
some enterococci
Causes suppurative cutaneous infections, toxic shock
syndrome, food
poisoning
S. aureus
Coagulase pos.
Ferments mannitol
(yellow colonies on
mannitol salt agar).
Usually DNase & thermonuclease pos.
S. aureus
S. aureus:
85%–90%
resistant to ________
penicillin
S. aureus:
most are _______-hemolytic (small zone)
beta
Coagulase-negative
staphylococci (CNS):
neg. Grow
on mannitol salt agar
but don’t ferment
mannitol. Sensitive to ___________
Novobiocin
UTI in young sexu-
ally active females, urethritis & prosta-
titis in males
GPC, usually in
clusters
S. saprophyticus
Coagulase neg. Resistant
to novobiocin. May
ferment mannitol.
S. saprophyticus
-Novobiocin only
performed when CNS
isolated from urine of
female.
Usually nonpathogenic. Found in environment &
on skin, mucous
membranes,
oropharynx
Large GPC in
pairs, tetrads
(predominant
arrangement),
clusters
Micrococcus
Often pigmented
(bright yellow,
orange, pink, tan).
High-domed
colonies.
Micrococcus
Key characteristics of Micrococcus
Catalase pos. Coagulase
neg. Oxidative.
Microdase (modified
oxidase) pos. Susceptible to bacitracin. Resistant to furazolidone & lysostaphin.
Not commonly iso-
lated. Must differenti-
ate from staph.
Usually only grow
aerobically.
Micrococcus
enterococci are __________ for catalase.
neg
Mannitol salt agar (MSA):
What color is pos?
example of pos?
turns yellow (from pink)
S. aureus pos
Mannitol salt agar (MSA):
7.5% salt inhibits most organisms
other than _______
Staph.
Causes 90% of
strep infections.
Strep sore throat,
rheumatic fever,
glomerulonephritis,
scarlet fever (scar-
latina), erysipelas,
puerperal sepsis,
impetigo
Group A streptococci
(GAS)
most common is S. pyogenes.***
Enterococcus:
Hydrolyzes esculin.
Grows in 6.5% NaCl
broth. PYR _____
pos
Streptococcus
pneumoniae:
Bile solubility ______
Sensitive to ___________
pos
optochin
Normal in upper
respiratory tract
of some. Most
common cause
of community-
acquired pneumo-
nia. Major cause
of otitis media***,
meningitis in
adults. Infects
sinuses, eyes
Streptococcus
pneumoniae
Viridans streptococci:
Resistant to _________.
Bile solubility _____.
optochin
neg
Normal in oral,
respiratory, GI mucosa. Opportunistic
pathogens. Frequent cause of
subacute bacterial
endocarditis.
Gingivitis & dental
caries (cavities)
Viridans streptococci
Optochin disk:
What is susceptible?
What is resistant?
S. pneumoniaesusceptible.
Viridans strep resistant
what is pos for bile solubility?
S. pneumoniaepos
