Colony Morphology Flashcards
refers to the inoculation of the clinical specimen onto laboratory media
Primary plating
Generally, microbiologists observe the colony
morphology of organisms isolated on primary culture
after how many hours?
18 to 24 hours
interpretation of primary cultures
Plate reading
laboratory media that contains added agents to inhibit the growth of certain species
selective media
permits the differentiation of bacterial strains based on colony morphology based on the ability of some bacteria, and not others
differential media
what agar support the growth of fastidious and non-fastidious organisms?
SBA and CHOC agar
what is the term called for hard to grown and requires additional growth factors?
fastidious organisms
it has the key ingredients of intact sheep red blood cells, vitamin K, and yeast extracted
anaerobic blood agar
- Nutritious medium
- for the isolation
and - subculturing of
obligate anaerobic
bacteria
anaerobic blood agar
- Hemolyzed
sheep red blood
cells - supplemented
with Hgb and
NAD
Chocolate agar
- Primary plating
and - subculturing of
fastidious
bacteria, - e.g., Haemophilus
and pathogenic
Neisseria spp
Chocolate agar
- carbohydrates
lactose, - salicin, and
- sucrose; and
- bile salts to
inhibit growth of
gram-positive
bacteria and
many
nonpathogenic
enteric bacteria
Hektoen energetic agar
- selective and
- differential
medium - for the primary
plating of stool
specimens - to aid in the
recovery of
intestinal
pathogens, - e.g., Salmonella
Hektoen enteric agar
- Lactose and
- bile salts,
- the low
concentration of
bile salts inhibits
gram-positive
bacteria but - permits the
growth of many
gram-negative
bacteria
MacConkey agar
- selective and
- differential
medium - for the isolation
of gram-negative
bacteria; - used for primary
plating and
subculturing
MacConkey agar
- Chocolate agar
base - containing the
antimicrobial
agents: - vancomycin,
colistin,
trimethoprim, and
nystatin
Modified thayer- martin agar
- selective primary
plating medium - for recovery of
Neisseria
gonorrhoeae and
Neisseria
meningitidis
Modified thayer - martin agar
- Dextrose
(glucose), - antimicrobials
can be added to
inhibit bacteria
Sabouraud dextrose agar
- Primary plating
and subculturing
of fungi
Sabouraud dextrose agar
- Intact sheep red
blood cells
Sheep blood agar
- Primary plating
and subculturing
of most bacterial
isolates
Sheep blood agar
provides additional nutrients to support
highly fastidious organisms
CHOC agar
a process in which bacteria selected for
further testing will be inoculated to other plates
Subculturing
supports most gram-negative rods,
especially Enterobacteriaceae
MAC agar
– color change as the pH
of environment decreases; produces pink, dark
pink, or red colonies
Lactose fermenters
remain clear and
colorless
Lactose non-fermenters
Growth on SBA and CHOC agar but not on MAC agar is
indicative of a?
Gram positive isolate or of a fastidious gram negative bacillus or coccus
A reaction caused by enzymatic or toxin activity of
bacteria observed in the SBA medium
Hemolysis
the passing of bright light through the bottom of the plate
or to determine whether the
organism is hemolytic
Transillumination
what agar does not display hemolysis?
CHOC agar
Organisms that are α-hemolytic or β-hemolytic on SBA
usually show what color?
green coloration
Partial lysing of RBCs in an SBA plate
a-hemolysis
Complete clearing of erythrocytes in SBA around or
under the colonies because of the complete lysis of
RBCs
b-hemolysis
produce a wide, deep, clear zone of β-hemolysis
group a b-hemolytic streptococci
produce a
narrow, diffuse zone of β-hemolysis close to the colony
group b b-hemolytic streptococci
generally produce smaller
colonies than gram-negative bacteria
gram positive bacteria
a hazy blanket of growth on the surface
that extends well beyond the streak lines.
swarming
produce colonies that are creamy, white with a dull surface, with feet or pedicles
Yeast
an inherent characteristic of a specific organism
confined generally to the colony
colony
old sock odor
s. aureus
fruity or grapelike
p. aeruginosa
putrid odor
p. mirabilis
musty or basement
haemophilus spp
freshy plowed field
nocardia spp
Comparative examination of colony
morphology of microorganisms growing on various
culture media.
plate reading
