Gram Positive Bacilli and Gram Negative Cocci (pics)

Question 1

Bacillus anthrasis

Answer 1

Question 2

Pathogenesis of B. anthracis

Answer 2

Question 3

Inhalational (Pulmonary) Anthrax/Woolsorter’s
Disease

Answer 3

Chest x-ray. There is widening of the mediastinum.

Question 4

Dried smear of B. anthracis

Answer 4

Question 5

LEFT: 5% Blood agar plate; RIGHT: Bicarbonatecontaining medium in 5-7% CO2

Answer 5

LEFT: organisms produce nonhemolytic gray to white, tenacious colonies with a rough texture and a ground-glass appearance.

RIGHT: Mucoid colonies can be appreciated because of the presence of capsule

Question 6

Blood agar plate

Answer 6

Comma-shaped outgrowths (Medusa head, “curled hair”) may project from the colony (if viewed in high magnification)

Question 7

Agar with bacteriophage

Answer 7

Lysis of B. anthracis by lytic phage gamma.

Question 8

Bacillus cereus.

Answer 8

Question 9

Corynebacterium diphtheriae

Answer 9

LEFT: Gram stain; RIGHT: Metachromatic Granules stain

Question 10

Pathogenesis of C. diphtheriae

Answer 10

Question 11

Corynebacterium Gravis, Intermedius, and Mitis in Chocolate agar added with tellurit

Answer 11

Note the BLACK color of the colonies formed as compared to the white colonies seen in blood agar alone

Question 12

C. diphtheriae in potassium tellurite plate

Answer 12

Note the presence of the grayish-black colonies indicating growth of the bacteria

Question 13

Loeffler slant

Answer 13

C. diphthteria grows on this and presence of cream to yellow colonies indicates the presence of the organism

Question 14

Elek’s Toxigenicity Test

Answer 14

Filter paper contains antitoxin, (+) control produces toxin, (-) control does not produce toxin. Antitoxin from the filter paper and the toxin from the test organism migrate in the agar and produces precipitate in the area where they are specific.

Question 15

Listeria monocytogenes in a blood culture

Answer 15

Note that this bacteria is facultative intracellular so some of the organism are seen inside and outside of the RBCs.

Question 16

Life cycle of Listeria monocytogenes

Answer 16

Virulence factors are encircled in yellow.

Question 17

Gram staining of Neisseria meningitidis

Answer 17

Notice the bacteria present in the cytoplasm of the PMNs (the cytoplasm does not stain so only the bacteria can be seen)