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
Sugar
Part of the cell wall

Question 4

Exotoxin is produced by…

Answer 4

Gram+ organisms
Exported from the cell
Proteins

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) - dark green - Strep. pneumoniae + viridans
Beta (complete) - yellow - Group A (pyogenes) and B Strep.
Gamma (none) - red - Enterococcus sp.

Question 8

Examples of: Alpha-haemolytic Streptococci?

Answer 8

Strep. pneumoniae + “viridans” group

Question 9

Examples of: Beta-haemolytic Streptococci?

Answer 9

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

Question 10

Examples of: Non-haemolytic Streptococci?

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

H. pylori
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

Gene transfer: Transformation

Answer 23

DNA from dead bacteria is taken up by living bacteria and incorporated into plasmids/ bacterial chromosome.

Question 24

Gene transfer: Conjugation

Answer 24

Sex pilus forms between bacteria to allow transfer of plasmid DNA.

Question 25

Gene transfer: Transduction

Answer 25

Viruses can transfer bacterial DNA between cells they infect.

Question 26

The 5 methods of spread of infection are...

Answer 26

Inhalation, Ingestion (faecal-oral), Inoculation (blood), mother to Infant, Intercourse (sex)

Question 27

Viruses contain RNA or DNA, never both. | True/ False?

Answer 27

True | Size of their capsid (protein coat) limits space

Question 28

Bactericidal antibiotics inhibit cell growth. | True/ False?

Answer 28

False | Kill bacteria directly - bacteriostatic inhibits cell growth

Question 29

What do glycopeptides treat?

Answer 29

Serious gram positive infections | *vancomycin

Question 30

Vancomycin is part of which family of antibiotics?

Answer 30

Glycopeptides

Question 31

Penicillins, cephalosporins and glycopeptides act on the bacterial ...

Answer 31

Cell wall

Question 32

Penicillins: - bactericidal/ bacteriostatic - safe/ not safe in pregnancy - excreted via kidneys/ urine/ liver

Answer 32

Bactericidal, safe in pregnancy, kidneys

Question 33

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

Answer 33

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

Question 34

Beta lactamase destroys which antibiotic?

Answer 34

Amoxicillin * there are different types of beta lacamases * psuedonomas aeruginosa, klebsialla, E. coli, staph. aureus

Question 35

What does co-amoxiclav treat?

Answer 35

Treats everything apart from pseudomonas and MRSA | Can be taken orally or IV

Question 36

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

Answer 36

Bactericidal, safe in pregnancy, kidneys + urine

Question 37

Glycopeptides are only active against Gram _ cell walls. *such as vancomycin

Answer 37

+ve

Question 38

Name the 3 macrolides!

Answer 38

Erythromycin, clarythromycin, azythromycin

Question 39

What are aminoglycosides used to treat? | *such as gentamicin

Answer 39

Read BNF summary

Question 40

Gentamicin belongs to which class of antibiotics?

Answer 40

Aminoglycosides

Question 41

Macrolides: - bactericidal/ bacteriostatic - safe/ not safe in pregnancy - excreted via kidneys/ urine/ liver *such as erythromycin

Answer 41

Bacteriostatic, erythromycin safe in pregnancy, liver

Question 42

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

Answer 42

Both bacteriostatic + bactericidal, not safe in pregnancy, urine

Question 43

Name the antibiotics that act on bacterial DNA!

Answer 43

Metronidazole, trimethoprim +/- sulphanimide, fluoroquinolones

Question 44

Metronidazole: - bactericidal/ bacteriostatic - safe/ not safe in pregnancy - treats aerobes/ anaerobes

Answer 44

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

Question 45

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

Answer 45

Bacteriostatic, co-trimoxazole

Question 46

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

Answer 46

Ciprofloxacin Co-amoxiclav Clindamycin Cephalosporins (ceftriaxone)