Aerobic Non–Spore-Forming
Gram-Positive Rodscontinued
Clinical Microbiology Review 172
ORGANISM PATHOGENICITY GRAM STAIN CULTURE KEY CHARACTERISTICS OTHER
Corynebacterium
jeikeium
Listeria
monocytogenes
Nocardia
Most commonly
isolated diph-
theroid. Highly
resistant to
antibiotics.
Grows from
0.5°–45°C. Cold
enrichment may
be used. Catalase
differentiates
from GBS. Motility
differentiates from
diphtheroids.
N. brasiliensismost
common species
to cause skin infec-
tions. N. asteroides
most common
species to cause
lung infections.
Same as other
commensal
corynebacteria.
Tiny colonies
with narrow
zone of indistinct
beta hemolysis.
Translucent, gray.
Slow-growing.
On SBA wrinkled,
dry, crumbly,
chalky white to
orange-tan, beta
hemolytic.
Hospital-acquired
pathogen.
Meningitis &
septicemia in new-
borns & immuno-
compromised.
Food poisoning.
Immunocompetent:
skin infections. Im-
munocompromised:
invasive pulmonary
& disseminated
infections.
Same as above.
Parallel sides,
rounded ends,
coccobacillary.
Singles, chains, or
diphtheroid
arrangement.
Fine branching
filaments with
fragmentation.
Often beaded.
Catalase pos. Rapid
sucrose urea (RSU) neg.
Catalase pos. Hippurate
hydrolysis pos. Esculin
pos. CAMP pos (hemolysis
looks like shovel, not
arrowhead). Tumbling
motility on wet mount.
Umbrella growth in
motility agar at RT but
not at 35°C.
Catalase pos. Partially
acid fast. Sulfur granules.
