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Rory's Year 5 pathology > Microbiology: Antimicrobial agents > Flashcards

Microbiology: Antimicrobial agents Flashcards

(55 cards)

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1
Q

What are the main categories of antibiotics?

A

-Penecillins (Beta-Lactam) -Cephalosporins (Beta-Lactam) -Carbapenems (Beta-Lactam) -Monobactams (Beta-Lactam) -Glycopeptides -Aminoglycosides (Inhibitor of protein synthesis) -Tetracyclines (Inhibitor of protein synthesis) -Macrolides/ Lincosamides/ Streptogramins – The MSL group (Inhibitors of protein synthesis) -Chloramphenicol (Inhibitor of protein synthesis) -Oxazolidinones (Inhibitor of protein synthesis) -Quinolones (Inhibitor of DNA synthesis) -Nitromidazoles (Inhibitor of DNA synthesis) -Rifamycins (Inhibitor of RNA synthesis) -Cell membrane toxins -Sulfonamides (Inhibitors of folate metabolism) -Diaminopyrimidines (Inhibitors of folate metabolism)

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2
Q

Inhibitors of cell wall synthesis: 2 types. What are they?

A

-Beta-lactams -Glycopeptides

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3
Q

4 examples of Beta-lactam antibiotics?

A

-Penecillins -Cephalosporins -Carbapenems -Monobactams -//⛢”Ben’s in Luck, because PENny’s Choice of CAR is a MONdeo”

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4
Q

2 examples of Glycopeptide antibiotics?

A

-Vancomycin -Teicoplanin

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5
Q

Beta lactam mechanism of action?

A

-Inactivate the enzymes involved in the terminal stages of cell wall synthesis (transpeptidases, aka penicillin binding proteins) -bacteriocidal, against rapidly dividing bacteria -Ineffective against bacteria that lack peptidoglycan cell walls (e.g. Mycoplasma or Chlamydia)

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6
Q

Beta lactam targets what?

A

-Transpeptidase

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7
Q

What bacteria does penicillin act on?

A

-Gram positive organisms, Streptococci, Clostridia. -Not S. Aureus //Broken down by an enzyme (β-lactamase) produced by S. aureus)

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8
Q

What bacteria does amoxacillin act on?

A

-Broad spectrum penicillin. Gram positive organisms, Streptococci, Clostridia. Extends coverage to Enterococci and Gram negative organisms ; -Not S. Aureus //Broken down by an enzyme (β-lactamase) produced by S. aureus)

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9
Q

What bacteria does flucloxacillin act on?

A

-Similar to penicillin although less active. -So Gram positive organisms, Streptococci, Clostridia. -Stable to β-lactamase produced by S. aureus.

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10
Q

What bacteria does piperacillin act on?

A

-(Similar to amoxicillin) -Broad spectrum penicillin Gram positive organisms, Streptococci, Clostridia. Extends coverage to Enterococci and Gram negative organisms ; -extends coverage to Pseudomonas and other non-enteric Gram negatives; broken down by β-lactamase produced by S. aureus and many Gram negative organisms. So not effective on S. Aureus and many Gram negative organisms

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11
Q

What bacteria do clavulanic acid and tazobactam act on?

A

-S. Aureus, Gram negatives and anaerobes -β-lactamase inhibitors. Protects penicillins from enzymatic breakdown and increases coverage.

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12
Q

How do bacteria develop resistance to Beta lactams?

A

-By producing Beta-Lactamase enzymes

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13
Q

3 Types of cephalosporins?

A

-1st, 2nd and 3rd generation

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14
Q

Cephalosporins: 4 types?

A

-Cephalexin: 1st generation -Cefuroxime: 2nd generation -Cefotaxime: 3rd generation -Ceftriaxone: 3rd generation

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15
Q

Glycopeptides target what bacteria?

A

-Only gram positive organisms

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16
Q

5 types of inhibitors of Protein Synthesis?

A

-Aminoglycosides (e.g. gentamicin, amikacin,tobramycin) -Tetracyclines -Macrolides (e.g. erythromycin) / Lincosamides (clindamycin) / Streptogramins (Synercid) – The MSL group -Chloramphenicol -Oxazolidinones (e.g. Linezolid)

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17
Q

Aminoglycosides: Mechanism?

A

-Inhibitor of protein synthesis -Aminoglycosides bind to the amino-acyl site of the 30s ribosomal unit -Rapid, bacteriocidal action

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18
Q

What types of bacteria do aminoglycosides have no activity on?

A

Anaerobes

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19
Q

Most significant side effect of aminoglycosides?

A

-Nephrotoxicity (Reduced kidney function)

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20
Q

Aminoglycosides work synergistically with what type of antibiotic?

A

-Beta Lactams

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21
Q

What bacteria do tetracyclines act on?

A

-Broad spectrum activity on intracellular pathogens

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22
Q

In what cases should tetracyclines not be given?

A

-Pregnancy and children

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23
Q

An example of an antibiotic that can cause a light sensitive rash as a side effect?

24
Q

Tetracycline mechanism of action?

Study These Flashcards
A

-Inhibitor of protein synthesis -Reversibly binds to 30S ribosomal subunit -Bacteriostatic

25
What bacteria do macrolides act on?
-Minimal gram -ve activity
26
Macrolide mechanism of action?
-Inhibitor of protein synthesis -Binds to 50s ribosomal unit
27
-In what cases are macrolide antibiotics particularly useful?
-For use in penicillin-allergic patients
28
In the case of penicillin-allergic patients, what antibiotic do you use?
-Macrolides
29
What antibiotic is associated with grey baby syndrome?
-Chloramphenicol
30
Chloramphenicol mechanism of action?
- Inhibitor of protein synthesis - Chloramphenicol binds to the **peptidyl transferase** of the 50S ribosomal subunit and inhibits the **formation of peptide bonds** during translation
31
Oxazolidinone mechanism of action?
-Inhibitor of protein synthesis -Binds to 23S component of 50s ribosomal unit.
32
What bacteria do oxazolidinones act on?
-Highly active against Gram positive organisms, including MRSA and VRE. Not active against most Gram negatives.
33
Types of inhibitors of DNA synthesis?
-Quinolones (eg ciprofloxacin) -Nitromidazoles (eg metronidazole)
34
An example of a quinolone?
-Ciprofloxacin
35
An example of a nitromidazole?
-Metronidazole
36
Fluoroquinolone mechanism of action?
-Inhibitor of DNA synthesis -Act on alpha-subunit of DNA gyrase
37
Ciprofloxacin, Levofloxacin and Moxifloxacin are all examples of what antibiotic?
-Fluroquinolones (aka quinolones)
38
Ciprofloxacin, Levofloxacin and Moxifloxacin are all examples of what antibiotic?
-Fluoroquinolones (aka quinolones)
39
What are fluoroquinolones used to treat?
-UTIs, pneumonia, atypical pneumonia & bacterial gastroenteritis
40
Nitromidazole mechanism of action?
-Inhibitor of DNA synthesis -Under anaerobic conditions, an active intermediate is produced which causes DNA strand breakage
41
Metronidazole & Tinidazole are examples of what antibiotic?
-Nitromidazoles
42
Types of inhibitors of RNA synthesis?
-Rifamycins (Only one)
43
An example of a rifamycin?
-Rifampicin
44
Mechanism of action of rifampicin?
-Inhibitor of RNA synthesis -Inhibits protein synthesis by binding to DNA-dependent RNA polymerase thereby inhibiting initiation
45
What extra precaution needs to be taken when giving rifampicin?
-Monitor LFTs (Due to hepatotoxicity) -Beware of other drugs metabolised by the liver (eg OCP) -Combine with other drugs to prevent resistance developing, which can occur easily through a point mutation causing a change in shape of RNA polymerase.
46
Antibiotics that act as cell membrane toxins?
-Daptomycin -Colistin
47
Types of inhibitors of folate metabolism
-Sulfonamides -Diaminopyrimidines (eg trimethoprim)
48
An example of a sulfonamide?
-Sulfamethoxazole
49
An example of a diaminopyrimidine?
-Trimethoprim
50
Mechanism of action of Sulfonamides?
-Inhibition of folate metabolism, therefore impairing DNA synthesis
51
Mechanism of action of Diaminopyrimidines?
-Inhibition of folate metabolism, therefore impairing DNA synthesis
52
Sulphonamides work synergistically with what antibiotic class?
-Diaminopyrimidines
53
Outline the mechanisms of antimicrobial resistance please
-Chemical modification or inactivation of the antibiotic -Modification or replacement of target -Reduced antibiotic accumulation (Impaired uptake or enhanced efflux) -Bypass antibiotic sensitive step
54
Give an example of inactivation as a mechanism of antibiotic resistance
-Beta lactamase enzyme produced to break down beta lactam antibiotics -Can occur in Staphylococcus aureus (//not MRSA) and Gram Negative Bacilli (Coliforms).
55
Give an example of altered targets as a mechanism of antibiotic resistance
-MRSA encodes an altered penicillin binding protein (PBP) which has a low affinity for beta-lactams -Comes from mecA gene -MRSA is able to function as normal, in high concentrations of Beta-lactams -(extra) Macrolides, 23S rRNA subunit changes conformation, reducing macrolide binding.

Rory's Year 5 pathology (39 decks)

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