Gram Stain Characteristics

Question 1

Micrococcus

Answer 1

GPC in clusters, often found in tetrads

Question 2

Aerococcus

Answer 2

GPC in clusters

Question 3

Rothia

Answer 3

GPC in clusters

Question 4

Streptococcus pneumoniae

Answer 4

GPC in pairs (lancet-shaped)

Can be gram variable

Question 5

Viridans group streptococci (including some s. pneumoniae)

Answer 5

GPC in pairs and chains

Question 6

Beta-hemolytic streptococci (eg. strep pyogenes)

Answer 6

GPC in pairs and chains

Question 7

Enterococcus

Answer 7

GPC in pairs and chains

Question 8

Abiotrophia

Answer 8

GPC in pairs and chains (nutritionally variant strep)

Question 9

Granulicatella

Answer 9

GPC in pairs and chains (nutritionally variant strep)

Question 10

Bacillus

Answer 10

GPR - may be big and boxy, may have spores

Can be gram variable or gram negative

Question 11

Clostridium

Answer 11

GPR - may be big and boxy, may have spores

Can be gram variable or gram negative

Question 12

Listeria

Answer 12

GPR, may appear coccobacillary

Question 13

Lactobacillus

Answer 13

GPR

Question 14

Eggerthelia

Answer 14

GPR

Question 15

Corynebacterium

Answer 15

GPR - coryneform

Question 16

Cutibacterium (formerly propionibacterium)

Answer 16

GPR - coryneform

Question 17

Actinomyces

Answer 17

GPR - coryneform, may be beaded and/or have sulfur granules on histopathology

Question 18

Erysipelothrix

Answer 18

GPR - coryneform

Question 19

Mycobacterium

Answer 19

Beaded GPR

Question 20

Nocardia

Answer 20

Beaded or branching, filamentous GPR

Question 21

Streptomyces

Answer 21

Branching, filamentous GPR

Question 22

Gordonia

Answer 22

Branching, filamentous GPR

Question 23

Tsukamurella

Answer 23

Branching, filamentous GPR

Question 24

Gardnerella vaginalis

Answer 24

Gram-variable rod

Question 25

Leptotrichia

Answer 25

Gram-variable rod | GNR - fusiform

Question 26

Veillonella

Answer 26

GNC

Question 27

Acidaminococcus

Answer 27

GNC

Question 28

Megasphaera

Answer 28

GNC

Question 29

Neisseria

Answer 29

GN diplococci

Question 30

Moraxella catarrhalis

Answer 30

GN diplococci or coccobacilli

Question 31

Haemophilus

Answer 31

GN coccobacilli

Question 32

Acinetobacter

Answer 32

GN coccobacilli (may be gram variable)

Question 33

Aggregatibacter

Answer 33

GN coccobacilli

Question 34

Pasteurella multocida

Answer 34

GN coccobacilli or GNR

Question 35

Bacteroides

Answer 35

GN coccobacilli

Question 36

Francisella tularensis

Answer 36

GN coccobacilli | Tiny gram-negative rods, "junky" gram stain

Question 37

Brucella

Answer 37

GN coccobacilli | Tiny gram-negative rods, "junky" gram stain

Question 38

Enterobacteriaceae

Answer 38

GNR

Question 39

Non-fermenters (pseudomonas, achromobacter, acinetobacter)

Answer 39

GNR

Question 40

HACEK

Answer 40

GNR

Question 41

Fusobacterium nucleatum

Answer 41

GNR - fusiform

Question 42

Capnocytophaga

Answer 42

GNR - fursiform

Question 43

Campylobacter

Answer 43

GNR - curved, "seagull-shaped"

Question 44

Helicobacter

Answer 44

GNR - curved

Question 45

Arcobacter

Answer 45

GNR - curved

Question 46

Anaerobiospirillum

Answer 46

GNR - curved

Question 47

Vibrio

Answer 47

GNR - curved/comma shaped