Gram Positive Bacilli

Front 1

Name the three ways in which GPB are categorized

Back 1

Gram stain morphology (branching or nonbranching)

Formation of spores

catalase reaction

Front 2

Name the catalase positive, spore forming GPB species

Back 2

Bacillus cereus

Bacillus anthracis

Front 3

Characteristics of (most) Bacillus species?

Back 3

Large rods

motile

hemolytic

catalase +

Front 4

Characteristics of Bacillus anthracis?

Back 4

non hemolytic

non motile

square-ended rods in singles or chains ("bamboo")

stiff consistency on blood agar

Front 5

Describe types of anthrax caused by B. anthracis

Back 5

Cutaneous - spore penetrates skin, causes ulceration ("black eschar"), 20% mortality rate

Pulmonary - "Woolsorter's Disease", inhalation of spores, 80-90% mortality rate if not treated early

Gastrointestinal - ingestion of spores, most patients die from toxemia and sepsis

Front 6

Clinical significance of B. cereus?

Back 6

Leads to food poisoning via emetic or enterotoxin

Enterotoxin - watery diarrhea 8-16 hours after ingestion of contaminated food, recovery w/in 24 hours of onset

Emetic toxin - Vomiting 0.5 - 6 hours after ingestion (usually rice), recovering 9 hours after onset

Front 7

Laboratory identification of B. cereus?

Back 7

Because B. cereus is part of normal stool flora positive identification must be confirmed from contaminated food source, not patient stool sample

Front 8

Name the catalase positive, non spore forming GPB species

Back 8

Listeria sp.

Corynebacterium sp.

Front 9

Name the catalase negative, non spore forming GPB species

Back 9

Erysipelothrix

Lactobacilli sp.

Gardnerella sp.

Arcanobacterium sp.

Front 10

Name the catalase positive, branching aerobic Actinomycetes GPB species

Back 10

Nocardia sp.

Streptomyces sp.

Rhodococcus

Front 11

Biochemical characteristics of Listeria species?

Back 11

catalase +

tumbling motility on wet mount

Umbrella shaped motility in semisolid media

CAMP + (shovel or wedge shape)

Front 12

Colony morphology of Listeria monocytogenes?

Back 12

small, grey colonies

narrow beta hemolysis

grows best at room temp, can grow at refrigerated temps

Front 13

Infections caused by Listeria monocytogenes?

Back 13

Pregnant females can pass on organism to fetus (usually results in stillbirth, if fetus is born alive there is a 50% mortality rate)

Neonatal Listeriosis - newborns contract organism in utero (early onset) which often leads to sepsis OR during vaginal birth (late onset) which often leads to meningitis

Invasive Listeriosis - bacteremia and meningitis in immunocompromised hosts

Gastroenteritis - in healthy individuals due to food contamination (often meat and dairy products)

Front 14

Significance of Lactobacillus?

Back 14

Normal flora of mouth, GI tract, female genital tract

Plays important role in maintaining homeostasis of female genital tract (keeps pH acidic, releases hydrogen peroxide which is poisonous to other bacteria)

Absence of Lactobacillus is major factor in developing bacterial vaginosis

Front 15

Morphology and characteristics of Nocardia species?

Back 15

slow aerobic growth (3-30 days)

chalky, matte, velvety appearance

will grow on blood agar, mycology media, and LJ

partially acid fast +

Lysozyme resistance +

grows in soil, water, decaying matter

Front 16

characteristics of N. brasiliensis infections?

Back 16

Causes cutaneous infections, usually a result of traumatic injury

3 types of cutaneous infections:

1) mycetoma - chronic, localized, painless, subcutaneous, swelling, presence of granules

2) Lymphocutaneous - infection spreads to lymphnodes

3) superficial skin infections - cellulitis and abscesses

Front 17

characteristics of N. asteroides infections?

Back 17

Pulmonary infections in immunocompromised patients

abscesses form in lungs

can disseminate to other parts of body

Front 18

Differentiation of N. braziliensis and N. asteroides?

Back 18

N. braziliensis = positive for casein and tyrosine hydrolysis

N. asteroides = negative for casein and tyrosine hydrolysis

Front 19

Which species of GPB is partially acid fast positive?

Back 19

Nocardia sp (use this test to differentiate from Streptomyces sp)

Front 20

Colony morphology of Arcanobacterium sp?

Back 20

Narrow beta hemolysis

may pit the agar or form black dot under colony

Front 21

Differentiation of A. haemolyticum and A. pyogenes?

Back 21

A. haemolyticum is reverse CAMP +

A. pyogenes is reverse CAMP -

Front 22

How do you identify Corynebacterium diphtheriae?

Back 22

Initial ID done with Loeffler's media (blue staining granules) or CTBA (brown halo around colonies)

Definitive ID requires demonstration of toxin production by the isolate with the Elek test

Front 23

Typical gram stain morphology of Corynebacterium species?

Back 23

Gram positive rods

club-shaped ("coryneform")

pleomorphic

palisading

May stain irregularly

Front 24

What are clue cells and with which bacterial species might you see them?

Back 24

Clue cells are epithelial cells covered in bacteria. Often observed with Gardnerella vaginalis infections.

Front 25

Differentiation of Corynebacterium species on blood agar?

Back 25

C. diphtheriae - small, beta hemolytic

C. jekeium - small, non hemolytic

C. urealyticum - pinpoint, non hemolytic