Gram-Negative Anaerobes Clinical Microbiology Review 206
ORGANISM PATHOGENICITY GRAM STAIN OTHER
Gram-negative cocci
Veillonella
Gram-negative rods
Bacteroides fragilis
Fusobacterium
Porphyromonas
Prevotella
May show weak red fluorescence under
UV light. Doesn’t grow on KVLB. Usually
doesn’t reduce nitrates.
Most common anaerobe isolated.
Resistant to bile. Hydrolyses esculin.
Turns BBE brown.
Indole pos. Most fluoresce chartreuse
(green-yellow) under UV light.
Slow growing. Brown to black on SBA.
Some fluoresce brick-red to orange
under UV light. Doesn’t grow on KVLB.
Slow growing. Some are pigmented.
Brown to black on SBA & KVLB. Some
fluoresce brick-red to orange under UV
light. Doesn’t grow on BBE.
Normal flora of upper respiratory
tract, GI & GU tracts. Usually in
mixed culture. Can cause infec-
tions in immunocompromised
Mixed infections below
diaphragm
Pulmonary infections, brain
abscesses, oral lesions
Head, neck, & pleuropulmonary
infections
Head, neck, & pleuropulmonary
infections
Tiny GNDC in pairs, clusters,
short chains. Can resemble
Neisseria
Pleomorphic, pale, irregu-
larly staining GNR
GNR. F. nucleatumis long &
thin with tapered ends
(spindle shaped)
GNCB
GNCB
