EXERCISE 16 Flashcards
(37 cards)
Assessment of gross colony characteristics is usually performed by visually inspecting [?] on the surface of agar plates
growth
Inspection of cultures is carried out by [?] and observing the surface of the agar for the presence of bacterial growth.
holding the plate in one hand
is a mass or cluster of bacteria forming on a solid culture medium as a result of repeated divisions of one or few organisms.
Colony
is consisting of only one species of microorganism
Pure culture
Importance of colonial morphology as a diagnostic tool
- Provide a [?] to the physician.
- Enhance the [?] through rapid reporting of results and by increasing the cost-effectiveness of laboratory testing.
- Play a [?] especially of automated procedures and other commercially available identification systems.
- presumptive identification
- quality of patient care
- significant role in quality control
Interpretation of Cultures
o generally observed after [?] hours of incubation where the bacteria are presumed in the logarithmic growth phase.
18 to 24 hrs
the media where organism grow is a
preliminary indicator
- Type of media supporting bacterial growth
- consider:
▪ generally, all bacteria grow on [?] because it is an enriched medium
▪ [?] as a selective culture media supports gram-negative organism but inhibits gram-positive organisms and fastidious gram-negative
▪ Growth on BAM but not on MAC is indicative of [?] or [?]
- Blood agar medium (BAM)
- MAC
- gram-positive isolate;
- fastidious gram-negative bacilli or cocci
Information derived from the type of culture media supporting bacteria growth must be correlated with the result of the [?].
initial Gram-staining
the [?] is a criterion (along with direct smear result, organisms’ virulence, site) for establishing clinical significance
predominance of the bacterial isolate
Number of Colonies Visible in each Quadrant
growth on #1
1+
Number of Colonies Visible in each Quadrant
growth on #1, #2
2+
Number of Colonies Visible in each Quadrant
growth on #1, #2, #3
3+
Number of Colonies Visible in each Quadrant
growth on #1, #2, #3, #4
4+
measured in millimeter or described in relative terms such as pinpoint, small, medium, large
Colony size
white, yellow, black, buff, orange, others
Colony pigmentation
Hemolytic pattern, change of color of pH indicator, pitting on the agar surface
Change in culture media resulting from bacterial growth
old stock (MSA):
Staphylococcus aureus
grape juice/ fruity:
Pseudomonas species
burned chocolate:
Proteus species
bleach:
Eikenella corrodens
freshly cut apples:
Alkaligenes faecalis
“fruity” :
Corynebacterium DF-3
musty basement:
Nocardia and Streptomyces
