Antibiotics Flashcards

1
Q

Define infection

A

Invasion and multiplication of pathogenic microbes

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2
Q

Define antibiotic

A

Antibacterial medication

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3
Q

Define anti-bacterial

A

Kills or inhibits growth of bacteria

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4
Q

Define bactericidal

A

Kills bacteria

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5
Q

Define bacteriostatic

A

Inhibits growth of bacteria (by affecting RNA and DNA)

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6
Q

What is the minimum bacterial concentration (MBC)?

A

Lowest concentration that kills 99.9% of a population

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7
Q

What is the minimum inhibitory concentration (MIC)?

A

Lowest concentration which inhibits visible growth of bacteria

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8
Q

What is the breakpoint?

A

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

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9
Q

Name 4 features of bacteria

A

1-10 um in size

DNA as a single chromosome (prokaryotes)

Independent metabolism and no organelles

Cell wall (differs from cell membrane)

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10
Q

Describe the cell wall of a gram +ve bacteria

A

Peptidoglycan cell wall

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11
Q

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

A

Gram +ve

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12
Q

Describe the cell wall of a gram -ve bacteria

A

Lipopolysaccharide cell wall

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13
Q

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

A

Gram -ve

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14
Q

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

A

Gram +ve

Has several layers of peptidoglycans

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15
Q

List the 4 classifications of bacteria

A

Gram positive cocci

Gram positive bacilli

Gram negative cocci

Gram negative bacilli

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16
Q

Give an example of a gram positive cocci bacteria

A

Staphylococcus species

Streptococcus

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17
Q

Give an example of a gram positive bacilli bacteria

A

Bacillus anthracis

Lactobacilli species

18
Q

Give an example of a gram negative cocci bacteria

A

Neisseria meningitidis

Haemophilus influenzae

19
Q

Give an example of a gram negative bacilli bacteria

A

Escherichia coli

Salmonella species

20
Q

What classification of bacteria are E. coli and salmonella?

A

Gram negative bacilli

21
Q

What classification of bacteria are Staphylococcus and Streptococcus species?

A

Gram positive cocci

22
Q

What are the 4 potential targets for antibiotic therapy?

A

Bacterial cell wall

Bacterial RNA & protein synthesis

Bacterial DNA structure & function

Folic acid synthesis

23
Q

What 2 classes of drugs target the bacterial cell wall?

What effect does this have on the bacteria?

A

Beta-lactams (penicillins, cephalosporins, carbapenems)

Glycopeptides

(Bactericidal)

24
Q

What 3 classes of drugs target RNA and protein synthesis?

What effect does this have on the bacteria?

A

Macrolides

Tetracyclines

Aminoglycosides

(Bacteriostatic)

25
Q

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

A

Quiolones

Nitroimidazoles

Nitofurantoin

(Bactericidal)

26
Q

What 2 classes of drugs target folic acid synthesis?

A

Trimethoprim

Sulphonamides

(Bacteriostatic)

27
Q

Why are cephalosporins now not used so much?

A

Broad spectrum of activity and kill more natural flora

Likely to cause C. diff

28
Q

What is the CURB-65 scale?

What actions are taken on the basis of this scale?

A

Confusion

Urea >7mmol/L

Respiratory rate >30 minute

BP <90mmHg systolic OR <60mHg diastolic

65 yrs >/=

Score > 1 - admit
Score >2 - IV treatment

29
Q

What is the bacterial target of beta-lactams?

What 3 types of drugs are in this family?

A

Bacterial cell wall

Penicillins
Cephalosporins
Carbapenums

30
Q

What class of drugs are fluclox/co-amox/taz in?

What are they used to treat?

A

Penicillins - beta-lactams - cell wall synthesis

Flucloxicillin - SSTI

Co-amoxiclav - mixed infections

Pipirecillin-tazobactum - anti-pseudomonal

31
Q

What class of drugs are ceftriaxone and ceftazidime in?

What are they used to treat?

What is a serious side effect?

A

Cephalasporins

Ceftriaxone - bacterial meningitis, ortho infections

Ceftazidime - LRTIs

Broad spectrum antibiotic, kill natural flora. High risk of C diff

32
Q

What class of drugs are erythromycin, clarithromycin and azithromycin in?

What are they used to treat?

A

Macrolides - RNA + protein synthesis

33
Q

What class of drugs is doxycycline in?

What is it used to treat?

A

Tetracycline - RNA + protein synthesis

Atypical bacterial with unusual cell wall e.g. chlamydia

34
Q

What class of drugs is gentamicin in?

What is it used to treat?

What is a caution with using this drug?

A

Aminoglycosides - RNA + protein synthesis

Severe gram -ve infections

Renal toxicity and therapeutic dosing
Only given IV

35
Q

What class of drugs is meropenum in?

What is it used to treat?

A

Carbapenums - beta-lactams - cell wall

ITU infections, drug resistant UTIs

36
Q

What class of drugs are ciprofloxacin and levofloxacin in?

What are they used to treat?

A

Quinolones - DNA structure and function

Anaerobic gram -ve infections
MRSA
LRTIs

37
Q

What class of drugs is metronidazole in?

What is it used to treat?

A

Nitromadazoles - DNA structure and function

Anaerobic infections e.g. abcess

38
Q

Discuss nitrofurantoin

A

Acts on bacterial DNA structure and function

Used to treat uncomplicated UTIs

Poor systemic bioavailability but concentrated in urine

39
Q

Discuss trimethoprim

A

Acts on bacterial folic acid synthesis

Used to treat uncomplicated UTIs

Not to be used in pregnancy

40
Q

What patient factors may affect your choice of antibiotics?

A

Allergy/intolerance

Renal/liver function

Immunocompromised/severity of infection

Route of administration

Polypharmacy

Age, ethnic group

Pregnant, breastfeeding, oral contraceptive

41
Q

Why are antibiotic guidelines useful?

A

Useful when deciding on empirical treatment

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