Micro - Clinical Bacteriology (Gram + Basics) Flashcards Preview

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Flashcards in Micro - Clinical Bacteriology (Gram + Basics) Deck (21):
1

What are the Gram-positive branching filaments bacteria? What are the characteristics that distinguish them from one another?

(1) ACTINOMYCES - anaerobe, not acid fast (2) NOCARDIA - aerobe, acid fast

2

Which of the Gram-positive branching filaments bacteria are aerobic versus anaerobic? Which is acid fast versus not acid fast?

AEROBIC, ACID FAST - Nocardia; Anaerobic, not acid fast - Actinomyces

3

What are the Gram-positive rods (bacilli)?

(1) CLOSTRIDIUM (2) CORYNEBACTERIUM (3) LISTERIA (4) BACILLUS (5) MYCOBACTERIUM

4

Which of the Gram-positive rods are actually acid fast?

Mycobacterium

5

Which of the Gram-positive rods is an aerobe, and which is an anaerobe?

AEROBE - Bacillus; ANAEROBE - Clostridium

6

What are the groups of Gram-positive cocci? How can they be distinguished?

(1) Staphylococcus - clusters, catalase positive (2) Streptococcus - chains, catalase negative

7

What characterizes all Staphylococcus? What are the names of the main species in Staphylococcus, and how can they be distinguished?

Gram + bacteria, cocci in clusters; (1) S. aureus - Coagulase positive (2) S. epidermidis - Coagulase negative, novobiocin sensitive (3) S. saprophyticus - Coagulase negative, novobiocin resistant

8

Of the Staphylococcus bacteria, which are coagulase positive? Which are novobiocin sensitive?

S. aureus = coagulase positive; S. epidermidis = novobiocin sensitive

9

What characterizes all Streptococcus? What are the names of the main species in Staphylococcus, and what is the main way to distinguish/categorize them?

Gram + bacteria, cocci in chains; differentiate species via Hemolysis: (1) ALPHA HEMOLYTIC - S. pneumoniae, Viridans streptococci (2) BETA HEMOLYTIC - S. pyogenes (Group A Strep), S. agalactiae (Group B Strep) (3) GAMMA HEMOLYTIC - Group D Enterococcus, Group D Nonenterococcus

10

What does alpha-hemolytic mean, and how do these kind of bacteria appear on blood agar plates? What are the alpha-hemolytic Streptococci? How can they be distinguished from one another?

Partial hemolysis, green; (1) S. PNEUMONIAE - capsule (+ quellung), optochin sensitive (2) VIRIDANS STREPTOCOCCI - no capusle, optochin resistant (Note: Enterococci may also be alpha-hemolytic or gamma-hemolytic)

11

What does beta-hemolytic mean, and how do these kind of bacteria appear on blood agar plates? What are the beta-hemolytic Streptococci? How can they be distinguished from one another?

Complete hemolysis, clear; (1) S. PYOGENES (GROUP A) - Bacitracin sensitive (2) S. AGALACTIAE (GROUP B) - Bacitracin resistant

12

What does gamma-hemolytic mean, and how do these kind of bacteria appear on blood agar plates? What are the gamma-hemolytic Streptococci? How can they be distinguished from one another?

No hemolysis, normal or no plate change; (1) GROUP D ENTEROCOCCUS - growth in bile AND 6.5% NaCl (2) GROUP D NONENTEROCOCCUS - growth only in bile NOT 6.5% NaCl

13

Give prominent examples of Group D Enterococcus versus Nonenterococcus.

ENTEROCOCCUS - E. faecalis; NONENTEROCOCCUS - S. bovis

14

What kind(s) of hemolysis do Enterococcus display?

Either alpha OR gamma hemolytic

15

What are the most important Gram-positive pathogens?

(1) Staphylococcus - particularly S. aureus (2) Streptococcus - particularly, S. pneumoniae, S. pyogenes, and S. agalactiae (3) Clostridium (4) Listeria (5) Bacillus (6) Mycobacterium

16

Which bacteria does novobiocin help us distinguish, and what are their different responses to it?

Coagulase negative Staphylococcus: (1) S. epidermidis - Novobiocin sensitive (2) S. saprophyticus - Novobiocin resistant

17

Which bacteria does optochin help us distinguish, and what are their different responses to it?

Alpha-hemolytic streptococci: (1) Viridans streptococci - Optochin resistant (2) S. pneumoniae - Optochin sensitive

18

Which bacteria does bacitracin help us distinguish, and what are their different responses to it?

Beta-hemolytic streptococci: (1) Group B Strep (S. agalactiae) - Bacitracin resistant (2) Group A Strep (S. pyogenes) - Bacitracin sensitive

19

How do alpha-hemolytic bacteria appear on blood agar? What are examples? What are characteristics that define/distinguish these bacteria?

Form green ring around colonies on blood agar; (1) Streptococcus pneumoniae - catalase negative & optochin sensitive (2) Viridans streptococci - catalase negative & optochin resistant

20

How do beta-hemolytic bacteria appear on blood agar? What are examples? What are characteristics that define/distinguish these bacteria?

Form clear area of hemolysis on blood agar; (1) Staphylococcus aureus - catalase and coagulase positive (2) Streptococcus pyogenes (Group A strep) - catalase negative & bacitracin sensitive (3) Streptococcus agalactiae (Group B strep) - catalase negative & bacitracin resistant (4) Listeria monocytogenes - tumbling motility, meningitis in newborns, unpasteurized milk

21

What kind of hemolysis does Listeria monocytogenes display? With what major things should you associate Listeria monocytogenes?

Beta-hemolytic; (1) Tumbling motility (of the bacteria itself) (2) Meningitis in newborns (3) Unpasteurized milk

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