Bacteria - Structure and Classification

Question 1

What is gram staining?

Answer 1

Method of staining bacterial cells where bacteria are stained with crystal violet dye

Question 2

What is gram positive?

Answer 2

Class of bacteria which retains crystal violet - due to thick peptidoglycan layer

PURPLE COLOUR

Question 3

What is gram negative?

Answer 3

Class of bacteria which do not retain crystal violet dye - Thin peptidoglycan layer sandwiched between inner and outer cell membrane

Question 4

What is the outer membrane in gram negative organisms called?

Answer 4

Lipopolysaccharide (LPS) - which is anchored to peptidoglycan by lipoproteins

Question 5

What are the main classes of bacteria by shape?

Answer 5

• Cocci - spherical
  
  • Diplococcus - 2 cocci
  • Streptococcus - chain
  • Staphylococcus - cluster
• Bacilli - rod shaped
• Spirilli - spiral shaped

Question 6

What is the capsule of a bacteria?

Answer 6

Polysaccharide layer that lies outside the cell envelope of some prokaryotes. It is considered a virulence factor. It can protect cells from phagocytosis, and can protect bacteria from desiccation.

Question 7

What are flagellae?

Answer 7

Whip like structures that consist of helical filaments which help the bacteria rapidly propel themselves through different media.

Question 8

What are fimbriae?

Answer 8

An appendage composed of curlin proteins that can be found on most gram positive bacteria and some gram negative bacteria. It is thinner and shorter than a flagellum. They are used to adhere to each other, animal cells, and inanimate objects.

Question 9

What is a Plasmid?

Answer 9

Mobile, independent, self-replicating circular units of dsDNA. They carry genes that may benefit the organisms survival, and can frequently be transmitted between organisms by horizontal gene transfer.

Question 10

What class of bacteria is S. Aureus?

Answer 10

Gram Positive Coagulase positive (has coagulase enzyme) Cocci

Question 11

Can you name Gram positive coagulase negative Staphylococci?

Answer 11

• S. hominis
• S. epidermidis
• S. Haemolyticus

Question 12

What class of bacteria is S. Pneumoniae?

Answer 12

Gram positive, alpha-haemolytic cocci

Question 13

What does alpha haemolysis mean?

Answer 13

Partial haemolysis

Question 14

What class of bacteria is S. viridans?

Answer 14

Gram positive, alpha haemolytic cocci

Question 15

What indicates partial haemolysis on blood agar plate?

Answer 15

Agar turns green - hydrogen peroxide produced by bacteria due to oxidation of haemoglobin to methoglobin

Question 16

What is beta-haemolysis?

Answer 16

Complete haemolysis - turns blood agar clear

Question 17

What does lancefield serotyping describe?

Answer 17

Specific carbohydrates present in the bacterial cell wall. Groups A, B and D are most clinically significant

Question 18

What class of bacteria is S. Pyogenes?

Answer 18

Gram negative, beta haemolytic group A strep

Question 19

What class of bacteria is S. agalactiae?

Answer 19

Gram positive, beta-haemolytic Group B strep

Question 20

What can S. pneumoniae (Group A strep) cause?

Answer 20

• Sore throats
• Cellulitis
• Necrotising fasciitis

Question 21

What class of bacteria is E. Faecalis?

Answer 21

Gram positive, non-haemolytic group D strep

Question 22

What class of bacteria are enterococci?

Answer 22

Gram positive, non-haemolytic streptococci

Question 23

What class of bacteria is L. monocytogenes?

Answer 23

Gram positive, aerobic bacilli

Question 24

What class of bacteria is diptheria?

Answer 24

Gram positive, aerobic bacilli

Question 25

What class of bacteria is C. difficile?

Answer 25

Gram positive, anaerobic bacilli

Question 26

What class of bacteria is C. Perfringens?

Answer 26

Gram positive, anaerobic bacilli

Question 27

What class of bacteria is C. Tetani?

Answer 27

Gram positive, anaerobic bacilli

Question 28

What class of bacteria is N. meningitidis (meningococcus)?

Answer 28

Gram negative diplococcus

Question 29

What class of bacteria is N. gonorrhoae?

Answer 29

Gram negative diplococcus

Question 30

What class of bacteria is M. catarrhalis?

Answer 30

Gram negative cocci

Question 31

What class of bacteria is E. Coli?

Answer 31

Gram negative lactose fermenting bacilli

Question 32

What class of bacteria is S. enterica?

Answer 32

Gram negative, non-lactose fermenting bacilli

Question 33

What class of bacteria is S. typhi?

Answer 33

Gram negative bacilli

Question 34

What class of bacteria is Shigella?

Answer 34

Gram-negative bacilli

Question 35

What class of bacteria is K. pneumoniae?

Answer 35

Gram-negative, lactose fermenting bacilli

Question 36

What class of bacteria is Proteus spp.?

Answer 36

Gram negative bacilli

Question 37

What are coliforms?

Answer 37

Gram-negative bacilli which can ferment lactose with the production of acid and gas when incubated at 35–37°C. Normally found in the gut

Question 38

What class of bacteria are Campylobacter spp.?

Answer 38

Gram negative, S-shaped bacteria

Question 39

What class of bacteria is H. Pylori?

Answer 39

Gram Negative, curved rods

Question 40

What class of bacteria is H. Influenzae?

Answer 40

Gram Negative, cocco-bacilli

Question 41

What class of bacteria is Pseudomonas spp.?

Answer 41

Gram negative, aerobic bacilli

Question 42

What class of bacteria is Bacteriodes spp.?

Answer 42

Gram-negative, anaerobic bacilli

Question 43

What is the staining used to identify mycobacterium?

Answer 43

Ziehl-Neelsen Stain

Question 44

What is does a positive Ziehl-Neelsen Staining mean?

Answer 44

Resistant to decolourisation by acid or alcohol following carbol fuschin staining

Question 45

What is a Spirochaete?

Answer 45

Long, spiral shaped bacteria, which is most easily seen by immunoflourescence

Question 46

What class of bacteria is T. Pallidum?

Answer 46

Spirochaete

Question 47

What class of bacteria is borellia burgdoferri?

Answer 47

Spriochaete

Question 48

What class of bacteria is Leptospira?

Answer 48

Spirochaete

Question 49

What class of bacteria is Chlamydia trachomatis?

Answer 49

Gram negative ovoid bacteria

Question 50

What class of bacteria is Legionella pneumophila?

Answer 50

Gram-negative