Staphylococci Clinical Microbiology Review 158
ORGANISM PATHOGENICITY GRAM STAIN COLONIES ON SBA KEY CHARACTERISTICS OTHER
Staphylococcusspp
S. aureus
Coagulase-negative
staphylococci (CNS)
Normal flora of skin,
mouth, pharynx,
vagina, urethra, GI
tract. Facultative
anaerobe. Grows on
most nonselective
media. Salt tolerant.
10%–60% are carriers.
Spread by direct
contact. 85%–90%
resistant to penicillin.
Normal on skin &
mucous membranes.
Often contaminant.
Usually only speciated
if from normally sterile
site. 50%–80% are
S. epidermidis.
GPC, usually in
clusters
GPC, usually in
clusters
GPC, usually in
clusters
1–3 mm, round,
smooth, convex,
glistening, opaque,
entire edge, buty-
rous (butter-like).
Most are beta
hemolytic (small
zone). May be
golden.
White, usually
nonhemolytic.
See specific organ-
isms below
Causes suppurative
cutaneous infec-
tions, toxic shock
syndrome, food
poisoning
Opportunistic
pathogen. Common
cause of hospital-
acquired UTI
Catalase pos.
Fermentative.
Microdase (modified
oxidase) neg. Resistant
to bacitracin. Suscepti-
ble to furazolidone &
lysostaphin.
Coagulase pos.
Ferments mannitol
(yellow colonies on
mannitol salt agar).
Usually DNase & ther-
monuclease pos.
Coagulase neg. Grow
on mannitol salt agar
but don’t ferment
mannitol. Sensitive to
novobiocin.
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