Macroscopic Appearances of Bacteria

Practice vocabulary flashcards covering colonial morphology, quantification scales, growth characteristics, and specific bacterial appearances based on lecture notes.

Presumptive identification

Also known as an educated guess or educated judgment based on evidence; it provides an initial idea of the organism (including gram reaction and morphology) to enhance patient care and reduce waiting times to $2-3$ days.

Reading Scale: 1+

A quantification value that can be read as rare.

Reading Scale: 2+

A quantification value that can be read as few.

Reading Scale: 3+

A quantification value that can be read as moderate.

Reading Scale: 4+

A quantification value that can be read as many.

Punctiform (Size)

Colonies that are less than $1\,mm$ in diameter.

Small (Size)

Colonies with a diameter of $1-2\,mm$.

Medium (Size)

Colonies with a diameter of $2-4\,mm$.

Large (Size)

Colonies with a diameter of $4-5\,mm$.

Motile (Colony Size)

Colonies larger than $5\,mm$ in diameter.

Filamentous (Form)

Colony shape characterized by individual thin projections that have a branching, root-like appearance.

Spindle (Form)

Colony shape that is long and thin with tapered ends, giving a rice-like appearance.

Swarming

A hazy blanket of growth on the surface that extends well beyond the streak lines, characteristic of highly motile bacteria like Proteus spp.

Entire (Margin)

Measurement of colony edges described as smooth.

Erose (Margin)

Colony edges characterized by notched edges.

Convex (Elevation)

A dome-like elevation of a bacterial colony.

Umbilicate (Elevation)

A crateriform elevation characterized by a depressed center or concave shape.

Umbonate (Elevation)

An elevation characterized by a raised or bulging center, appearing convex.

Translucent (Density)

Specific to Streptococcus pyogenes because they grow a very thin colony; viewed using transillumination.

Brittle (Consistency)

A consistency where the colony exists in splinters when touched with a loop, typical of Nocardia spp.

Mucoid (Consistency)

A mucus-like consistency characteristic of Klebsiella pneumoniae.

Prodigiosin

A brick-red pigment produced by Serratia marcescens at room temperature.

Pyocyanin

A pigment that produces a greenish metallic sheen or tinge in Pseudomonas aeruginosa.

Old stock/MSA odor

A smell like clothes or papers stocked for years, characteristic of Staphylococcus aureus.

Mousy/mouse-nest odor

A strong and musky smell characteristic of Haemophilus spp.

Freshly-plowed odor

A smell described as a mix of heat and rain, characteristic of Nocardia spp.

Hemolysis

The lysis of red blood cells observed in Blood Agar Plate (BAP), typically containing $5\%$ sheep blood.

Turbidity

Cloudiness in liquid media (like TSB) due to growth, indicating a facultative anaerobe.

Pellicle

Formation of a ring at the top of liquid media, indicating the bacteria is an obligate aerobe.

Sedimentation

Formation of sediments at the bottom of liquid media, indicating the bacteria is an obligate anaerobe.

Hockey Puck

The specific colonial appearance associated with Moraxella spp.

Molar Tooth

The specific colonial appearance associated with Actinomyces israelii.