Antibacterial agents Flashcards

1
Q

definition of antibiotics

A

chemical product of microbes that inhibits or kills another organism.
OR
Natural substance produced by micro-organisms to kill each other.

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2
Q

Define antimicrobial agents

A

drugs used to kill organism.
synthetic- similar effect to antibiotics
semi synthehtic- modified from antibiotics.

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3
Q

2 types of bacterial killing

A

Bacteristatic- inhibit bacterial growth

Bactericidal- kills bacteria.

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4
Q

Define MIC

A

Minimal inhibitory concentration

concentration of antibiotic at which visible growth is inhibited.

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5
Q

Synergism

A

activity of 2 antimicrobials together is greeter than the sum of their activity separately.

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6
Q

Antagonism

A

one agent dimities the effect of another.

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7
Q

Indifference

A

activity unaffected by that of another.

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8
Q

Antibiotic targets include:

A
cell wall
protein synthesis
DNA synthesis
RNA synthesis
Plasma membrane
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9
Q

Main component of bacterial cell wall

A

Peptidoglycan

found in gram +ve and -ve.

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10
Q

2 cell wall synthesis inhibitors

A

B lactam- affect peptidocylcan cross linking

Glycopeptides.- affect peptidoglycan cross linking.

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11
Q

B lactams include:

A

penicillins- amoxicillin
Cephalosporins- cefuroxime
Carbapenems- meropenem, imipenem
Monobactams- aztreonam

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12
Q

Glycopeptide only work on what type of bacteria.

A

gram +ve bacteria.

cannot penetrate gram -ve outer membrane.

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13
Q

Most common example of a glycopeptide

A

vancomycin

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14
Q

Types of protein synthesis inhibitors.

A

Aminoglycoside
Macrolides Lincosamides Steptogramins (MLS)
Tetracyclines
Oxadolidilones

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15
Q

Most common amincoglyoside and mechanism of action

A

Gentamicin

bind to 30s subunit

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16
Q

Most common MLS and mechanism of action.

A

Erthromycin
Cindamycin
Bind to 50 s subunit

17
Q

Most common Tetracylcines and mechanism of action

A

Doxytetracycline

bind to 30s subunit

18
Q

Most common Oxazolidinones and mechanism of action

A

Linezolid

Bind to 50s or 70s subunit.

19
Q

Types of DNA synthesis inhibitors.

A

Trimethoprim +sulphonamide= Co-trimoxazole.

Quinolones and fluoroquinolones

20
Q

Co-trimooxazole mechanism of action

A

inhibit folate synthesis by inhibiting- dihydropteroate synthetase.

21
Q

Most common Quinolones and fluoroquinolones and mechanism of action

A

Ciprofloxacin

Inhibit 1 or both DNA gyrase and topoisomerase.

22
Q

RNA synthesis inhibtior

A

Rifampicin.

23
Q

Rifamcin mechanism of action

A

prevents the synthesis of mRNA

24
Q

Uses of colistin

A

last line drug when resistance to everything has been proved.

25
What type of bacteria is daptomycin used to treat.
Gram +ve | inserts lipophilic tail into cell membrane result in depolarisation
26
General side effects
Nausea, vommiting, headahce and skin rashes.
27
Side effects of aminoglycoslides
Reversible renal impairment on accumulation | Irreversible ototoxicity.- ear.
28
Side effects of B lactams
allergic reactions
29
side effect of linezolid
bone marrow depression
30
What causes c.difficile
to over use of antibiotics.
31
Strategy of antibiotic use
1- Empiric therpay- best guess therapy 2-targeted therapy- predict susceptibility and infecting organism 3-susecptibilty guided treatment- based on cultures.
32
How do you treat bacterial infections
Initially broad spectrum | once diagnosis known use a narrow spectrum antibiotic.
33
Treatment for MRSA
Flucloxacillin
34
Treatment for streptococcus pyogenes
Benzylpenicillin
35
Treatment for anaerobes
Metronidazole
36
3 Reasons for combining antibiotics
to increase efficacy to provide adequately broad spectrum To reduce risk of resistance.
37
treatment for gram +ves
vancomycin
38
treatment for gram -ves
cephlosporins
39
Treatment of bacteria is dependent on
concentration at the site of action right amount of concentration time