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Path Y > Microbiology - Antimicrobial Agents 1 > Flashcards

Microbiology - Antimicrobial Agents 1 Flashcards

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1
Q

What 3 groups of antibiotics are classified as beta lactams?

A

Penicillins
Cephalosporins
Carbapenems

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2
Q

Name 2 glycopeptide antibiotics

A

Vancomycin

Teicoplanin

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3
Q

Describe the mechanism of action of beta lactams

A

Inhibits transpeptidase, which is an enzyme that forms cross links during the formation of the cell wall.
The resulting cell wall is therefore weak, and so the bacteria lyse because of osmotic pressure.

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4
Q

How does the cell wall of gram pos and gram neg bacteria differ?

A

Gram pos has thick peptidoglycan in cell wall

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5
Q

What bacteria is penicillin active against?

A

Gram positive

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6
Q

What bacteria is amoxicillin active against?

A

Broad spectrum: gram pos and many gram neg

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7
Q

Is streptococci gram pos or neg?

A

Gram pos

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8
Q

Which beta lactam antibiotic is effective against pseudomonas?

A

Piperacillin

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9
Q

How can beta lactam resistance be overcome? Give 2 examples of drugs?

A

Include a beta lactamase inhibitor

  • Clavulanic acid + amoxicllin (in co-amoxiclav)
  • Tazocin (piperacillin & tazobactam)
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10
Q

Is pseudomonas gram pos or gram neg?

A 
Gram neg
(Pseudo"moan"as - 'moan' = negative)
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11
Q

Is neisseria meningitis gram pos or gram neg?

A 
Gram neg
(Neisseria starts with N = negative)
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12
Q

Recall an antibiotic that is associated with C. difficile

A

Ceftriaxone (cephalosporin)

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13
Q

Which beta lactam antibiotics are used to treat to ESBL producing organisms?

A

Carbapenems

as ESBL producing organisms are resistant to cephalosporins

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14
Q

recall a caution of beta lactam antibiotic. do they cross the BBB?

A

Excreted renally so reduce dose if renal impairment

do not cross BBB

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15
Q

What type of bacteria are glycopeptides effective against?

A

Gram pos only - they are large molecules so can’t penetrate gram neg cell wall

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16
Q

What 2 infections are glycopeptides particularly useful for?

A

MRSA infection

C difficile

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17
Q

What is a caution of glycopeptide antibiotics?

A

They are nephrotoxic

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18
Q

Recall the broad mechanism of action of glycopeptide antibiotics

A

Prevent peptide cross links in cell wall

inhibit cell wall synthesis

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19
Q

Recall the broad mechanism of action of aminoglycosides

A

Bind to 30s ribosomal subunit, preventing elongation of polypeptide chain
(inhibit protein synthesis)
-bactericidal

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20
Q

Recall 2 examples of aminoglycoside antibiotics

A

gentamicin

amikacin

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21
Q

What type of bacteria are aminoglycoside antibiotics effective against?

A

Gram neg

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22
Q

Recall 2 toxicities of aminoglycosides

A

Ototoxicity

Nephrotoxicity

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23
Q

What type of bacteria are macrolides effective against?

A

Gram pos

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24
Q

What are macrolides particularly useful for?

A

Mild staph or strep infections in patients who are allergic to penicillin

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25
Recall 3 macrolide antibiotics
Azithromycin Clarithromycin Eryhromycin
26
What type of bacteria are tetracylines effective against?
broad spectrum - intracellular organisms
27
Recall a class of antibiotic you should never give to children or pregnant women
Tetracyclines
28
Recall one side effect of tetracycline antibiotics
photosensitivity rash (summer effect)
29
Recall the broad mechanism of action of macrolides
Bind to the 50s subunit of ribosomes | bacteriostatic
30
Recall the broad mechanism of action of tetracyclines
Bind to 30s subunit of ribosomes | bacteriostatic
31
What type of bacteria is chloramphenicol effective against?
Many - it is v broad spectrum
32
Why is chloramphenicol rarely used?
Risk of aplastic anaemia and grey baby syndrome in neonates due to inability to metabolise drug
33
Recall 2 specific bacteria that macrolides are effective against
Campylobacter sp | Legionella pneumophila
34
Recall the broad mechanism of action of chloramphenicol
Binds to 50s subunit of ribosomes - inhibits formation of peptide bonds during translation -bacteriostatic
35
Recall the broad mechanism of action of oxazolidinones
Binds to the 23s component of 50s subunit of ribosomes to prevent 70s subunit formation
36
Recall two types of bacteria that oxazolidinones are particularly active against
MRSA and VRE (vancomycin resistant enterococci)
37
Recall an example of oxazolidinones
Linezolid
38
Recall 2 potential side effects of oxazolidinones
Thrombocytopaenia & optic neuritis
39
Recall the broad mechanism of action of fluoroquinolones
Act on alpha subunit of DNA gyrase (inhibit DNA synthesis) - bactericidal
40
Recall 4 uses of fluoroquinolones
UTI Pneumonia Atypical pneumonia Bacterial gastroenteritis
41
Recall 2 examples of fluoroquinolone antibiotics
Levofloxacin | Moxifloxacin
42
Give an example of a nitroimidazole antibiotic
Metronidazole
43
Recall types of organisms that metronidazole is effective against
Anaerobes | Protozoa
44
When should metronidazole be taken?
Right after visiting the toilet as it sits in bladder
45
Recall the broad mechanism of action of rifamycins
Binds to DNA-dependent RNA polymerase to inhibit RNA synthesis example is rifampicin
46
Recall the main use of rifampicin
TB treatment
47
Recall one side effect of rifampicin
Turns secretions orange
48
Recall one condition of rifampicin prescription
Should never be prescribed alone as resistance develops very quickly
49
Colistin is very toxic. Why is it coming back into use?
It is active agianst certain multi-drug resistant bacteria
50
What is daptomycin licensed for the treatment of?
MRSA | VRE
51
Recall the 2 classes of antibiotic that inhibit folate synthesis
Sulphonamides | Diaminopyrimidines
52
Give an example of a sulphonamide
sulfamethoxazole
53
What is the main use of trimethoprim
Uncomplicated UTI
54
What are the 4 main mechanisms of resistance? Give examples
BEAT drug action 1. Bypass antibiotic sensitive step in pathway e.g MRSA 2. Enzyme mediated drug inactivation e.g beta lactamases 3. Impairment of accumulation of the drug e.g tetracyclines 4. Modification of the drugs target in the microbe e.g quinolone
55
Which antibiotic is best for treating pneumocystis jiroveci pneumonia?
this is a HIV defining disease | sulphamethoxazole + trimethoprim (co-trimoxazole)
56
What is the broad mechanism of action of nitroimidazoles?
Inhibit DNA synthesis
57
Which bacteria typically forms "gram pos cocci in clusters"?
Staphylococcus
58
Which bacteria typically forms "gram pos cocci in chains"?
Streptococcus | Strep sounds like 'stripe' = chain
59
What gram stain status are enterococci?
Positive | "Enter-o-coccus" = like letting someone in, positive thing to do
60
Is haemophilus gram pos or neg?
Gram neg | Ha"emo"philus - emo = negative
61
Is listeria gram pos or neg?
Positive | Lister = good man = positive
62
name 2 organisms that produce ESBL?
e coli | klebsiella pneumoniae
63
what 2 classes of antibiotics inhibit cell wall synthesis
beta-lactam antibiotics, glycopeptides
64
what 3 penicillins are broken down by beta-lactamase?
penicillin amoxicillin piperacillin
65
does ceftriaxone cover psueodmonas?
no
66
what type of bacteria is colistin used for? what's a caution?
gram -ve | nephrotoxic and reserved for use against multi-resistant organisms
67
give an example of a diaminopyrimidine
trimethoprim
68
What 2 antibiotics classes inhibit cell wall synthesis?
beta-lactam antibiotics, glycopeptides
69
What 5 antibiotics classes inhibit protein synthesis?
``` aminoglycosdies tetracyclines macrolides chloramphenicol oxazolidiones ```
70
give 2 risks of chloramphenicol?
aplastic anaemia | grey baby syndrome - can't metabolise drug
71
what 2 antibiotics classes are inhibitors of DNA synthesis?
fluroquinolones | nitroimidazoles
72
what drug class inhibits RNA synthesis?
rifamycin
73
what 2 antibiotic classes are cell membrane toxins?
daptomycin | colisitin
74
outline the gram staining procedure and results?
first step in gram staining is the use of crystal violet dye for the slide's initial staining. next step, also known as fixing the dye, involves using iodine to form crystal violet- iodine complex to prevent easy removal of dye. finally, a decolorizer, often solvent of ethanol and acetone, is used to remove the dye. If the bacteria stays purple, they are Gram-positive. If the bacteria turns pink or red, they are Gram-negative.
75
give an example of a tetracycline
doxycycline
76
who should not be given tetracylines and why
pregnancy women growing children deposits in bone and teeth
77
what antibiotic should you give as prophylaxis if someone is bitten?
co amoxiclav
78
what drug works best for MRSA
vancomycin

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