Microbiology

Question 1

Gram+ organisms stain…

Answer 1

Purple

Stain well due to thick peptidoglycan layer

Question 2

Gram- organisms stain…

Answer 2

Pink

Thinner peptidoglycan layer doesn’t retain stain well

Question 3

Endotoxin is produced by…

Answer 3

Gram- organisms

Part of the cell wall

Question 4

Exotoxin is produced by…

Answer 4

Gram+ organisms

Exported from the cell

Question 5

Gram+ cocci in chains are?

Answer 5

Streptococci

Question 6

Gram+ cocci in clusters are?

Answer 6

Staphylococci

Question 7

The test to classify different Streptococci spp.?

Answer 7

Haemolysis
Alpha (partial) - Strep. pneumoniae + viridans
Beta (complete) - Group A (pyogenes) and B Strep.
Gamma (none) - Enterococcus sp.

Question 8

Examples of: Alpha-haemolytic Streptococci?
(Is this partial/full/no haemolysis)

Answer 8

Strep. pneumoniae + “viridans” group

Question 9

Examples of: Beta-haemolytic Streptococci?
(Is this partial/full/no haemolysis)

Answer 9

Group A Strep. (Strep. pyogenes), Group B Strep.

Question 10

Examples of: Non-haemolytic Streptococci?
(Is this partial/full/no haemolysis)

Answer 10

Enterococcus sp.

Question 11

The test to distinguish Staphylococcus aureus from other Staph. spp.?

Answer 11

Coagulase test
+ve = Staph. aureus
-ve = other Staph. spp. (common skin commensals)

Question 12

Treatment of choice for Staph. aureus infection?

Answer 12

Flucloxacillin

Question 13

Examples of gram- cocci in pairs (diplococci)

Answer 13

Neisseria meningitidis and Neisseria gonorrhoeae

Question 14

Some examples of Gram- bacilli

Answer 14

Bordetella
H. influenzae
Coliforms
Pseudomonas
Campylobacter

Question 15

Examples of coliforms that are gut commensals

Answer 15

E. coli
Klebsiella sp.
Proteus sp.

Question 16

Examples of coliforms that are gut pathogens

Answer 16

Salmonella sp.
Shigella sp.
E. coli 0157

Question 17

The name of the toxin produced by E. coli 0157 is…

Answer 17

Verotoxin (VTEC)

Question 18

Treatment of choice for coliform infections?

Answer 18

Gentamicin

Question 19

Examples of strict aerobes (2)

Answer 19

Pseudomonas sp. (Gram- bacilli)

Legionella sp. (Gram- bacilli)

Question 20

Examples of strict anaerobes (2)

Answer 20

Clostridium spp. (Gram+ bacilli)

Bacteroides spp. (Gram- bacilli)

Question 21

Treatment of choice for anaerobic infections?

Answer 21

Metronidazole

Question 22

Genetic variation in bacteria is dangerous because…

Answer 22

Resistance to antibiotics may develop.

Question 23

The 5 methods of spread of infection are…

Answer 23

Inhalation, Ingestion, Inoculation, mother to Infant, Intercourse

Question 24

Bactericidal antibiotics inhibit cell growth. True/False?

Answer 24

False

Kill bacteria directly - bacteriostatic inhibits cell growth

Question 25

Vancomycin is part of which family of antibiotics?

Answer 25

Glycopeptides

Question 26

Penicillins, cephalosporins and glycopeptides act on the bacterial ___ ___

Answer 26

Cell wall

Question 27

Penicillins are bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

Answer 27

Bactericidal, safe in pregnancy, kidneys

Question 28

Flucloxacillin is a ___ spectrum antibiotic. Which organisms is it effective against?

Answer 28

Narrow | Staph and Strep only (1st line for Staph aureus)

Question 29

Beta lactamase destroys which antibiotic?

Answer 29

Amoxicillin

Question 30

Cephalosporins are bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

Answer 30

Bactericidal, safe in pregnancy, kidneys + urine

Question 31

Glycopeptides are only active against Gram _ cell walls

Answer 31

+ve

Question 32

Can you name the 3 macrolides?

Answer 32

Erythromycin, clarythromycin, azythromycin

Question 33

Gentamicin belongs to which class of antibiotics?

Answer 33

Aminoglycosides

Question 34

Macrolides are bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

Answer 34

Bacteriostatic, erythromycin safe in pregnancy, liver

Question 35

Gentamicin [aminoglycoside] is bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

Answer 35

Both bacteriostatic + bactericidal, not safe in pregnancy, urine

Question 36

Name the antibiotics that act on bacterial DNA

Answer 36

Metronidazole, trimethoprim +/- sulphanimide, fluoroquinolones

Question 37

Metronidazole is bactericidal/bacteriostatic, safe/not safe in pregnancy, treats aerobes/anaerobes

Answer 37

Bactericidal, safe in pregnancy, anaerobes (Clostridium and Bacteroides)

Question 38

Trimethoprim +/- sulphonamide is bactericidal/bacteriostatic, can be combined with sulphonamide to form _____

Answer 38

Bacteriostatic, co-trimoxazole

Question 39

The 4 antibiotics that most commonly cause C diff infection are...

Answer 39

Ciprofloxacin Co-amoxiclav Clindamycin Cephalosporins (ceftriaxone)