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PART ONE REVISION. > MICROBIOLOGY - Antimicrobials > Flashcards

MICROBIOLOGY - Antimicrobials Flashcards

1
Q

Which antibiotics inhibit bacterial cell wall synthesis? (3)

A

Penicillins, cephalosporins (ceftriaxone), vancomycin

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2
Q

What is the mechanism of action of fluoroquinolones?

A

BACTERICIDAL
Gram +ve: Inhibit topoisomerase IV

Gram -ve (more potent):
Inhibit DNA replication by action on bacterial DNA gyrase

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3
Q

Systemically, what can chloramphenicol cause?

A

Aplastic anaemia

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4
Q

Which antibiotics inhibit protein synthesis? (5)

Which antibiotics inhibit 30S subunit

Which antibiotics inhibit 50S subunit

A

30S: tetracycline, aminoglycosides (messenger RNA)
50S: Macrolides, Lincosamides, Chloramphenicol

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5
Q

What antibiotics inhibit cell wall synthesis?

A

Beta lactam antibiotics - penicillin, cephalosporins, vancomycin

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6
Q

What antibiotics inhibit folic acid synthesis?

A

Sulphonamides
Trimethoprim

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7
Q

What antibiotics inhibit DNA gyrase and transcription?

A

Fluoroquinolones

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8
Q

Which antibiotic is the most retino-toxic when given intravitreally?

A

Gentamicin (gram negative cover)

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9
Q

What are aminoglycosides not effective against?

A

Streptococcus and strict anaerobes

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10
Q

what is the mechanism of action of azole antifungals (fluconazole, itraconazole, ketoconazole)?

A

inhibit cell membrane synthesis - they inhibit the synthesis of sterols by inhibiting P450 dependent enzymes (C14-demethylase) which are an important constituent in fungal cell membranes (anti-mycotics)

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11
Q

What ocular side effect occurs with prolonged use of ciprofloxacin?

A

Corneal crystalline precipitates

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12
Q

What type of bacteria do tetracyclines target? (3)

A

Gram +ve
Gram -ve
Chlamydia

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13
Q

Which drug can be used for infections caused by aspergillus and candida?

A

Topical amphotericin

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14
Q

Which antibiotics are known to be associated with IIH?

A
  1. Tetracyclines
  2. Fluoroquinolones
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15
Q

Which antibiotics are bacteriocidal? (4)

A
  1. Aminoglycosides
  2. B-Lactam
  3. Vancomycin
  4. Fluoroquinolones
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16
Q

Which antibiotics are bacteriostatic? (4)

A
  1. Chloramphenicol
  2. Macrolides
  3. Tetracycline
  4. Sulphonamides
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17
Q

What is the mechanism of action of chloramphenicol?

A

BACTERIOSTATIC
50S subunit:
inhibits peptidyl-transferase and prevents peptide bond formation of to amino acids

18
Q

What is the mechanism of action of macrolides?

A

BACTERIOSTATIC
50S Subunit: interfering with translocation

Broad spectrum: Gram + ve > atypical (mycoplasma/ chlamydia) > Gram -ve.

19
Q

What is the mechanism of action of tetracyclines?

A

TETRA blocks tRNA on Thirty Subunit

BACTERIOSTATIC
inhibition of aminoacyltransferase tRNA to 30S subunit preventing binding to A-site.

20
Q

What is the mechanism of action of sulphonamides?

A

BACTERIOSTATIC
inhibits dihydropteroate synthase –> converts para-aminobenzoic acid to folate

21
Q

What is the mechanism of action of aminoglycosides?

A

BACTERICIDAL: GRAM -VE.

30S Subunit:
Prevents binding of mRNA to ribosome leading to mRNA misreading and premature termination of protein synthesis

22
Q

What is the mechanism of action of Beta Lactams?

A

BACTERICIDAL
Inhibits crosslinks of peptidoglycan strands causing cell lysis

23
Q

What is the mechanism of action of vancomycin

A

BACTERICIDAL
Binds to pentapeptide chains and prevents peptidoglycan assembly

Targets Gram +ve.

24
Q

What is the mechanism of action of fluoroquinolone?

A

Inhibits bacterial DNA gyrase

25
Q

What is the mechanism of action of metronidazole?

A

Disrupts DNA synthesis targets anaerobes

26
Q

What are aminoglycosides effective against?

What are they not effective against?

A
  1. aerobic gram negative bacili
  2. proteus
  3. staphylococcus

non effective against:
1. streptococcus
2. anaerobes

27
Q

What is the most common side effect of gentamicin?

A

oscilopsia then cochlear injury then renal toxicity

28
Q

What antimicrobials affect cell wall synthesis? (3)

A

penicillins
cephalosporins
vancomycin

29
Q

What antimicrobials affect protein synthesis? (4)

A

tetracycline
gentamicin
erythromycin
chloramphenicol

30
Q

Which antibiotic has the best ocular penetration when given orally?

A

ciprofloxacin (fluoroquinolones)

31
Q

What are the second generation fluoroquinolones? (2)

What are the third generation fluoroquinolones? (1)

What are the fourth generation fluoroquinolones? (1)

A

Second gen - cipro, ofloxacin,
Third gen - levofloxacin,
Fourth gen - Moxifloxacin

32
Q

Mechanism of action diagram of anti-microbials

A
33
Q

What are the
1st generation cephalosporins
2nd generation cephalosporins
3rd generation cephalosporins
4th generation cephalosporins

A

1 - FA/PHA - cefazolin
2 - Cefuroxime
3 - ONE/IME - ceftriaxone, ceftazidine
4 - PI - Cefepime

34
Q

What are cephalosporins active against which generation?

A

1st - gram positive (staph/strep)

2nd - gram +ve + some gram -ve (haemophilus, neisseria)

3rd - gram +ve + gram -ve bacilli and pseudomonas

35
Q

What bacteria are cephalosporins NOT effective against (3)

A

Listeria, Legionella, MRSA

36
Q

What is the mechanism of action of antimicrobials?

A
37
Q

What is the mechanism of action of micafungin?

A

Interferers with glucan synthesis, which is an essential component of fungal cell walls.

38
Q

What is the mechanism of action of polyene antifungal drugs (amphotericin, nystatin)

A

Interact with sterols in cell membrane to form channels through which small molecules leak from inside of fungal cell to the outside.

39
Q

What is the mechanism of action of foscarnet?

A

pyrophosphate analogue which Reversibly inhibits viral-specific DNA polymerase and reverse transcriptase

40
Q

Which antimicrobial agents are used in the treatment of acanthomoeba keratitis? (4)

A

Aminoglycosides (neomycin)
Diamidines (Brolene)
Imidazole (ketoconazole)
Antiseptic biocides (polyhexamethylene biguanide)

PART ONE REVISION. (77 decks)

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