DIFFERENTIAL CHARACTERISTICS OF ANAEROBIC NON-SPORE FORMING BACILLI AND COCCI

Question 1

Anaerobic, straight or slightly curved, Grampositive rods that are banded or beaded

Answer 1

GRAM STAIN OF Actinomyces

Question 2

Pale-staining, pleomorphic, Gram-negative rods
with a “safety pin” appearance

Answer 2

GRAM STAIN OF Bacteroides fragilis

Question 3

Pale-staining, thin, Gram-negative rods

Answer 3

GRAM STAIN OF Bacteroides ureolyticus

Question 4

Gram-positive diphtheroids; that are coccoid or
pointed in shape with bifurcated (forked) ends
which resemble a shape of a “dog bone”

Answer 4

GRAM STAIN OF Bifidobacterium spp.

Question 5

Gram positive rods in young culture that turn
Gram negative with age; Have subterminal
spores

Answer 5

GRAM STAIN OF Clostridium septicum

Question 6

Pleomorphic, Gram-positive rods that are
seagull wing-shaped

Answer 6

GRAM STAIN OF Eubacterium

Question 7

Spindle-shaped, Gram-negative rods that
resemble a Capnocytophaga

Answer 7

GRAM STAIN OF Fusobacterium nucleatum

Question 8

Spindle-shaped, Gram-negative rods that
resemble a Capnocytophaga

Answer 8

GRAM STAIN OF Fusobacterium nucleatum

Question 9

Large-fusiform Gram-negative rods

Answer 9

GRAM STAIN OF Leptotrichia

Question 10

Gram positive cocci that are paired singly, pairs
or in tetrads

Answer 10

GRAM STAIN OF Peptococcus niger

Question 11

Large, Gram-positive coccobacilli in chains

Answer 11

GRAM STAIN OF Peptostreptococcus
anaerobius

Question 12

Gram negative coccobacilli

Answer 12

GRAM STAIN OF Porphyromonas

Question 13

Diphtheroids-like, Gram-positive rods; that have
a palisade arrangement

Answer 13

GRAM STAIN OF Propionibacterium
(anaerobic diphtheroids)

Question 14

Gram negative rods

Answer 14

GRAM STAIN OF Prevotella

Question 15

Tiny Gram-negative diplococci

Answer 15

GRAM STAIN OF Veillonella parvula

Question 16

spider-like or wooly
appearance

Answer 16

young colonies of actinomyces

Question 17

“molar tooth”
appearance

Answer 17

old colonies of actinomyces

Question 18

Grayish-white, circular, smooth, and
non-hemolytic

Answer 18

Bacteroides fragilis

Question 19

Colonies corrode (pit) the agar

Answer 19

Bacteroides ureolyticus

Question 20

Small, white, shiny and convex
colonies

Answer 20

Bifidobacterium spp.

Question 21

Formation of Rhizoid margins that
resemble “medusa head”

Answer 21

Clostridium septicum

Question 22

Fluorescent chartreuse color

Answer 22

Eubacterium

Question 23

The medium exhibits a green color
upon air exposure; colonies have
“breadcrumb-like” appearance

Answer 23

Fusobacterium nucleatum

Question 24

Pinpoint colonies

Answer 24

Lactobacillus

Question 25

“Raspberry-like” colonies

Answer 25

Leptotrichia

Question 26

Small black and shiny colonies

Answer 26

Peptococcus niger

Question 27

Grayish-white colonies that emits foul
odor

Answer 27

Peptostreptococcus
anaerobius

Question 28

Brown, mucoid colonies with brick red
fluorescence

Answer 28

Porphyromonas

Question 29

Small, grayish-white colonies

Answer 29

Propionibacterium
(anaerobic diphtheroids)

Question 30

White, Shiny colonies with a brick-red
fluorescence

Answer 30

Prevotella

Question 31

Red fluorescence

Answer 31

Veillonella parvula