Microbiology Flashcards

1
Q

What are the three ways an antibiotic can act on the cell?

A

Act on the bacterial cell wall
Affecting the bacterial ribosome
Acting on bacterial DNA directly

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2
Q

Penicillins act to break the bacterial strand of DNA - True/False?

A

False - they act to inhibit cell wall synthesis

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3
Q

What facilitates the action of penicillins?

A

b-lactam ring

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4
Q

What are the benefits of using penicillin?

A

safe to use in healthy and pregnant patients

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5
Q

What are the disadvantages of penicillins?

A

Hypersensitivity in some patients

Rapid excretion requires more frequent dosing

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6
Q

What species is penicillin effective on?

A
Clostridium
Streptococcum
Bacteroides
Neisseria
S. Aureus
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7
Q

Clostridium

A

Gram +

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8
Q

Streptococcus

A

Gram +

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9
Q

Bacteroides

A

Gram -

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10
Q

Neisserin

A

Gram -

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11
Q

Staphylococcus

A

Gram +

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12
Q

What types of bacteria is Flucloxacillin effective against?

A

Gram +

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13
Q

Flucloxacillin is narrow spectrum - True/False?

A

True

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14
Q

What types of bacteria is flucloxacillin used against?

A

staphylococci

streptococci

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15
Q

What sort of infection is flucloxacillin used for?

A

skin infection, wound infection, cellulitis

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16
Q

For what type of infection is Flucloxacillin the drug of choice?

A

Staphylococcus aureus

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17
Q

What are the benefits of amoxicillin?

A

safe and well tolerated

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18
Q

What are the disadvantages of amoxicillin?

A

less effective in bacteria which have developed b-lactamase

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19
Q

What species is amoxicillin effective against?

A
Clostridium
Streptococcus
Enterococcus
E.coli
Haemophilus influenzae
Neisseria
Bacteroides
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20
Q

Enterococcus

A

Gram +

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21
Q

E.Coli

A

Gram -

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22
Q

Haemophilus Influenzae

A

Gram -

23
Q

Neisseria

A

gram -

24
Q

What is co-amoxiclav?

A

combined antibiotic, amoxicillin and clavulanic acid

25
Q

What is clavulanic acid?

A

b-lactamase inhibitor

26
Q

Which bacteria can co-amoxiclav treat that amoxicillin cannot?

A

staphylococcus

improves outcomes for other species

27
Q

Piperacillin/Tazobactam?

A

Combination of antibiotic and tazobactam b-lactamase inhibitor

28
Q

What does piperacillin/Tazobactam treat?

A

almost anything apart from MRSA and resistanct coliforms

29
Q

How do cephalosporins act?

A

inhibit cell wall synthesis by preventing cross linking of peptidoglycan

30
Q

What is the disadvantage of cephalosporins?

A

significantly affect normal gut flora

31
Q

Give a first gen cephalosporin

A

cefalexin -UTI

32
Q

2nd Gen cephalosporin

A

cefuroxime

33
Q

3rd Gen Cephalosporin

A

cefixime - Gonnorhoea

ceftriaxone - meningitis

34
Q

4th Gen Cephalosporin

A

Ceftazidime - pseudomonas

35
Q

Glycopeptides

A

Vancomycin

Teicoplanin

36
Q

How do glycopeptides work?

A

inhibit cell wall synthesis but by binding growing pentapeptide chains and preventing cross-linking

37
Q

What are the issues with glycopeptides?

A

Has to be given IV
Can be toxic to renal failure patients
Not absorbed from the gut

38
Q

What infection can vancomycin be used to treat?

A

C.diff

39
Q

What forms of antibiotics affect protein synthesis?

A

macrolides
tetracyclines
aminoglycosides

40
Q

How do antibiotics affecting proteins synthesis work?

A

attach to bacterial ribosomes - bacteriostatic not bacteriacidal

41
Q

What is the exception to the bacteriostatic rule in protein synthesis?

A

aminoglycosides where binding the ribosome is lethal

42
Q

Examples of macrolides

A

erythromycin
clarithromycin
azithromycin

43
Q

How are macrolides excreted?

A

liver –> biliary tract –> gut

44
Q

What are macrolides particularly useful for treating?

A

intracellular bacteria because they are lipophillic and can pass through cell membrane
Legionella

45
Q

Which macrolide is safe in pregnancy?

A

erythromycin

46
Q

Where are macrolides useful?

A

where bacteria do not have a proper cell wall

47
Q

Which species do macrolides work well on?

A
clostridium
streptococcus
enterococcus
staphylococus
MRSA
Neisseria
Haemophilia influenzae
Bacteroides
48
Q

Aminoglycoside

A

Gentamycin

49
Q

What do aminoglycosides mostly act on?

A

Gram -, aerobic organisms, coliforms, pseudomonas

50
Q

What are the disadvantages of aminoglycosides?

A

narrow therapeutic index
damage to kidneys
damage to VIII cranial nerve - deafness and balance issues

51
Q

Which species do aminoglycosides act on?

A
MRSA
S.Aureus
Pseudomonas aeruginosa
E.coli
Neisseria
52
Q

Tetracycline in Tayside

A

Doxycycline

53
Q

What is doxycycline useful for treating?

A

atypical pneumonia

chest/skin infections in patients who are penicillin allergic