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

Microbiology: Antimicrobial agents Flashcards

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?

A

Tetracycline

24
Q

Tetracycline mechanism of action?

A

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

25
Q

What bacteria do macrolides act on?

A

-Minimal gram -ve activity

26
Q

Macrolide mechanism of action?

A

-Inhibitor of protein synthesis -Binds to 50s ribosomal unit

27
Q

-In what cases are macrolide antibiotics particularly useful?

A

-For use in penicillin-allergic patients

28
Q

In the case of penicillin-allergic patients, what antibiotic do you use?

A

-Macrolides

29
Q

What antibiotic is associated with grey baby syndrome?

A

-Chloramphenicol

30
Q

Chloramphenicol mechanism of action?

A
  • 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
Q

Oxazolidinone mechanism of action?

A

-Inhibitor of protein synthesis -Binds to 23S component of 50s ribosomal unit.

32
Q

What bacteria do oxazolidinones act on?

A

-Highly active against Gram positive organisms, including MRSA and VRE. Not active against most Gram negatives.

33
Q

Types of inhibitors of DNA synthesis?

A

-Quinolones (eg ciprofloxacin) -Nitromidazoles (eg metronidazole)

34
Q

An example of a quinolone?

A

-Ciprofloxacin

35
Q

An example of a nitromidazole?

A

-Metronidazole

36
Q

Fluoroquinolone mechanism of action?

A

-Inhibitor of DNA synthesis -Act on alpha-subunit of DNA gyrase

37
Q

Ciprofloxacin, Levofloxacin and Moxifloxacin are all examples of what antibiotic?

A

-Fluroquinolones (aka quinolones)

38
Q

Ciprofloxacin, Levofloxacin and Moxifloxacin are all examples of what antibiotic?

A

-Fluoroquinolones (aka quinolones)

39
Q

What are fluoroquinolones used to treat?

A

-UTIs, pneumonia, atypical pneumonia & bacterial gastroenteritis

40
Q

Nitromidazole mechanism of action?

A

-Inhibitor of DNA synthesis -Under anaerobic conditions, an active intermediate is produced which causes DNA strand breakage

41
Q

Metronidazole & Tinidazole are examples of what antibiotic?

A

-Nitromidazoles

42
Q

Types of inhibitors of RNA synthesis?

A

-Rifamycins (Only one)

43
Q

An example of a rifamycin?

A

-Rifampicin

44
Q

Mechanism of action of rifampicin?

A

-Inhibitor of RNA synthesis -Inhibits protein synthesis by binding to DNA-dependent RNA polymerase thereby inhibiting initiation

45
Q

What extra precaution needs to be taken when giving rifampicin?

A

-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
Q

Antibiotics that act as cell membrane toxins?

A

-Daptomycin -Colistin

47
Q

Types of inhibitors of folate metabolism

A

-Sulfonamides -Diaminopyrimidines (eg trimethoprim)

48
Q

An example of a sulfonamide?

A

-Sulfamethoxazole

49
Q

An example of a diaminopyrimidine?

A

-Trimethoprim

50
Q

Mechanism of action of Sulfonamides?

A

-Inhibition of folate metabolism, therefore impairing DNA synthesis

51
Q

Mechanism of action of Diaminopyrimidines?

A

-Inhibition of folate metabolism, therefore impairing DNA synthesis

52
Q

Sulphonamides work synergistically with what antibiotic class?

A

-Diaminopyrimidines

53
Q

Outline the mechanisms of antimicrobial resistance please

A

-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
Q

Give an example of inactivation as a mechanism of antibiotic resistance

A

-Beta lactamase enzyme produced to break down beta lactam antibiotics -Can occur in Staphylococcus aureus (//not MRSA) and Gram Negative Bacilli (Coliforms).

55
Q

Give an example of altered targets as a mechanism of antibiotic resistance

A

-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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