Antibiotics

Question 1

Define infection

Answer 1

Invasion and multiplication of pathogenic microbes

Question 2

Define antibiotic

Answer 2

Antibacterial medication

Question 3

Define anti-bacterial

Answer 3

Kills or inhibits growth of bacteria

Question 4

Define bactericidal

Answer 4

Kills bacteria

Question 5

Define bacteriostatic

Answer 5

Inhibits growth of bacteria (by affecting RNA and DNA)

Question 6

What is the minimum bacterial concentration (MBC)?

Answer 6

Lowest concentration that kills 99.9% of a population

Question 7

What is the minimum inhibitory concentration (MIC)?

Answer 7

Lowest concentration which inhibits visible growth of bacteria

Question 8

What is the breakpoint?

Answer 8

MIC cut-off which separates strains where there is a high likelihood of treatment succeeding from those where treatment is more likely to fail

Question 9

Name 4 features of bacteria

Answer 9

1-10 um in size

DNA as a single chromosome (prokaryotes)

Independent metabolism and no organelles

Cell wall (differs from cell membrane)

Question 10

Describe the cell wall of a gram +ve bacteria

Answer 10

Peptidoglycan cell wall

Question 11

If a bacteria has a peptidoglycan cell wall, is it gram +ve or -ve?

Answer 11

Gram +ve

Question 12

Describe the cell wall of a gram -ve bacteria

Answer 12

Lipopolysaccharide cell wall

Question 13

If a bacteria has a lipopolysaccharide cell wall, is it gram +ve or -ve?

Answer 13

Gram -ve

Question 14

Which cell wall is thicker, gram +ve or gram -ve?

Answer 14

Gram +ve

Has several layers of peptidoglycans

Question 15

List the 4 classifications of bacteria

Answer 15

Gram positive cocci

Gram positive bacilli

Gram negative cocci

Gram negative bacilli

Question 16

Give an example of a gram positive cocci bacteria

Answer 16

Staphylococcus species

Streptococcus

Question 17

Give an example of a gram positive bacilli bacteria

Answer 17

Bacillus anthracis

Lactobacilli species

Question 18

Give an example of a gram negative cocci bacteria

Answer 18

Neisseria meningitidis

Haemophilus influenzae

Question 19

Give an example of a gram negative bacilli bacteria

Answer 19

Escherichia coli

Salmonella species

Question 20

What classification of bacteria are E. coli and salmonella?

Answer 20

Gram negative bacilli

Question 21

What classification of bacteria are Staphylococcus and Streptococcus species?

Answer 21

Gram positive cocci

Question 22

What are the 4 potential targets for antibiotic therapy?

Answer 22

Bacterial cell wall

Bacterial RNA & protein synthesis

Bacterial DNA structure & function

Folic acid synthesis

Question 23

What 2 classes of drugs target the bacterial cell wall?

What effect does this have on the bacteria?

Answer 23

Beta-lactams (penicillins, cephalosporins, carbapenems)

Glycopeptides

(Bactericidal)

Question 24

What 3 classes of drugs target RNA and protein synthesis?

What effect does this have on the bacteria?

Answer 24

Macrolides

Tetracyclines

Aminoglycosides

(Bacteriostatic)

Question 25

What 3 classes of drugs target bacterial DNA structure and function?

Answer 25

Quiolones Nitroimidazoles Nitofurantoin (Bactericidal)

Question 26

What 2 classes of drugs target folic acid synthesis?

Answer 26

Trimethoprim Sulphonamides (Bacteriostatic)

Question 27

Why are cephalosporins now not used so much?

Answer 27

Broad spectrum of activity and kill more natural flora Likely to cause C. diff

Question 28

What is the CURB-65 scale? What actions are taken on the basis of this scale?

Answer 28

Confusion Urea >7mmol/L Respiratory rate >30 minute BP <90mmHg systolic OR <60mHg diastolic 65 yrs >/= Score > 1 - admit Score >2 - IV treatment

Question 29

What is the bacterial target of beta-lactams? What 3 types of drugs are in this family?

Answer 29

Bacterial cell wall Penicillins Cephalosporins Carbapenums

Question 30

What class of drugs are fluclox/co-amox/taz in? What are they used to treat?

Answer 30

Penicillins - beta-lactams - cell wall synthesis Flucloxicillin - SSTI Co-amoxiclav - mixed infections Pipirecillin-tazobactum - anti-pseudomonal

Question 31

What class of drugs are ceftriaxone and ceftazidime in? What are they used to treat? What is a serious side effect?

Answer 31

Cephalasporins Ceftriaxone - bacterial meningitis, ortho infections Ceftazidime - LRTIs Broad spectrum antibiotic, kill natural flora. High risk of C diff

Question 32

What class of drugs are erythromycin, clarithromycin and azithromycin in? What are they used to treat?

Answer 32

Macrolides - RNA + protein synthesis

Question 33

What class of drugs is doxycycline in? What is it used to treat?

Answer 33

Tetracycline - RNA + protein synthesis Atypical bacterial with unusual cell wall e.g. chlamydia

Question 34

What class of drugs is gentamicin in? What is it used to treat? What is a caution with using this drug?

Answer 34

Aminoglycosides - RNA + protein synthesis Severe gram -ve infections Renal toxicity and therapeutic dosing Only given IV

Question 35

What class of drugs is meropenum in? What is it used to treat?

Answer 35

Carbapenums - beta-lactams - cell wall ITU infections, drug resistant UTIs

Question 36

What class of drugs are ciprofloxacin and levofloxacin in? What are they used to treat?

Answer 36

Quinolones - DNA structure and function Anaerobic gram -ve infections MRSA LRTIs

Question 37

What class of drugs is metronidazole in? What is it used to treat?

Answer 37

Nitromadazoles - DNA structure and function Anaerobic infections e.g. abcess

Question 38

Discuss nitrofurantoin

Answer 38

Acts on bacterial DNA structure and function Used to treat uncomplicated UTIs Poor systemic bioavailability but concentrated in urine

Question 39

Discuss trimethoprim

Answer 39

Acts on bacterial folic acid synthesis Used to treat uncomplicated UTIs Not to be used in pregnancy

Question 40

What patient factors may affect your choice of antibiotics?

Answer 40

Allergy/intolerance Renal/liver function Immunocompromised/severity of infection Route of administration Polypharmacy Age, ethnic group Pregnant, breastfeeding, oral contraceptive

Question 41

Why are antibiotic guidelines useful?

Answer 41

Useful when deciding on empirical treatment The BNF can be useful but most hospital trusts develop their own guidelines based on cost, epidemiology etc.