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Antibiotics > Cell Wall Synthesis Inhibitors > Flashcards

Cell Wall Synthesis Inhibitors Flashcards

1
Q

How do Beta Lactems work?

A

Bind to active site of transpeptidase enzyme (PBP) which catalyses cross linking of terminal peptide components of the linear polymer chains

Leads to weakening of the cell wall structure, build up in i travel pulse osmotic pressure and lysis of bacterial cells

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2
Q

What are 4 types of penicillins

A
  1. natural penicillins
  2. penicillinase resistant penicillins
  3. aminopenicillins (broad spectrum) + beta lactemase inhibitors
  4. anti pseudomonal penicillins (extended spectrum) + beta lactamase inhibitor
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3
Q

What are two types of natural penicillins?

A

Penicillin G and Penicillin V

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4
Q

What are 3 types of Penicillin G?

A

Pen G Potassium
Pen G Procaine
Pen G Benzathine

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5
Q

for natural pencilling, What is the
a) route of administration
b) main target organisms
c) penetration into CSF
d) excretion
e) distribution into storage tissue

A

a) Pen G Potassium = IV; Pen G Procaine = IM; Pen G Benzathine = IM; Pen V = Oral (better absorption than Pen V bc acid stable)
b) - gram positive, some gram neg (meningococci, gonococci), spirochetes (treponema pallidum *use pen G benzathine), beta lactamase negative strains
c) IV aqueous Pen G reaches higher concentrations than procaine or benzathine; penetration increased if meninges inflamed
d) renal (can be blocked by probenecid to prolong effect)
e) Pen G procaine and benzathine can distribute into storage tissues to be released slowly

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6
Q

4 examples of penicillinase-resistant penicillins?

A

a. methicillin
b. cloxacillin
c. oxacillin
d. flucloxacillin

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7
Q

4 examples of penicillnase resistant penicillins?

A

a. methicillin
b. cloxacillin
c. oxacillin
d. flucloxacillin

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8
Q

for penicillinase resistant penicillins, what is the
a) route of administration
b) main target organisms
c) penetration into CSF
d) Excretion
e) mechanism of action

A

a) IV, IM, Oral
b) gram positive penicillinase producing staphylococci and other gram positives
*ig organism is susceptible to pen G, less effective
c) does not achieve therapeutic levels
d) renal
e) bulky side groups confers protection from beta lactamases by limiting their accessibility to catalytic site of action

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9
Q

examples of 2 aminopenicillins

A

a. ampicillin
b. amoxicillin

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10
Q

For aminopenicillins,
a) route of administration
b) target organisms
c) penetration into CSF
d) excretion
e) Usually prescribed with what?

A

a) Ampicillin: Oral, IV; Amoxicillin: Oral (better than ampicillin)
b) Ampicillin & Amoxicillin: Gram positive & Gram Negatives (broad spectrum) EXCEPT pseudomonas + klebsiella;
c) IV yes, better in inflamed meninges
d) renal
e) Ampicillin + Sulbactem (unasyn); Amoxicillin + Clauvanate (augmentin)

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11
Q

example of antipseudomonal penicillin?

A

piperacillin

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12
Q

for antipseudomonal penicillins,
a) route of administration
b) target organism
c) penetration into CSF
d) excretion
e) usually combined with?

A

a) IV
b) Gram negs (including pseudomonas + klebsiella) + gram positives; anaerobes
c) good in inflamed meninges
d) renal
e) tazobactem (zosyn)

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13
Q

How do beta lactamase inhibitors work?

A
  1. Clauvanic Acid = suicide inhibitor of beta lactamase
  2. Sulbactem + tazobactem allosteric inhibitors
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14
Q

for beta lactamase combination drugs,
a) route of administration
b) main target organisms/ types of infection
c) penetration into CSF
d) excretion

A

a) Augmentin = oral, IV; Unasyn = IV; Zosyn = IV
b) Augmentin = Staph, H. influenzae, Gonococci, E .Coli/ Skin, lower respiratory tract infections, UTI; Unasyn = S. aureus, Gram neg aerobes, anaerobes/ skin. intra-abdominal, gynae infections; zosyn = broad af/ appendicitis, moderate to severe nosocomial pneumonia
c) clauvanic acid & tazobactem no; sulbactam need meningeal inflammation
d) renal

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15
Q

4 mechanisms of resistance to penicillin?

A
  1. PBP altered, reducing affinity for penicillins (MRSA expresses PBP2a, reduced affinity for penicillin)
  2. Production of beta lactamase resulting in hydrolysis of beta lactam ring
  3. Decreased ability of antibiotic to reach PBP when bacteria decreases porin production
  4. Presence of efflux pumps
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16
Q

adverse reactions of penicillins?

A
  1. allergy/hypersensitivity - SJS + TEN
  2. CDAD (ampicillin & augmentin)
  3. Neurotoxicity
  4. Hepatotoxicity
  5. Anosmia
  6. In patients with renal failure, high doses of penicillins can cause seizures
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17
Q

How are cephalosporins produced?

A

produced from 7-aminocephalosporanic acid; modification at position 7 of beta lactam ring alters anti bacterial activity;
substitution at position 3 of the dihydrothiazine ring alters the metabolism and PK properties of the drugs

18
Q

first gen cephalosporin a) examples (2) b) useful spectrum
c) method of administration

A

a) cefazolin, cephalexin
b) gram positives (streptococci [except if penicillin resistant], staph [except if methicillin resistant]); cefazolin the 2nd line for staph for pt with allergic rxn to penicillins
c) oral except cefazolin (IV)

19
Q

second gen cephalosporin a) example b) useful spectrum

A

a) cefuroxime
b) e. coli, klebsiella, proteus, h. influenzae

20
Q

third gen cephalosporin a) examples b) useful spectrum
c) method of administration

A

a) ceftriaxone, ceftazidime
b) enterobacter, p. aeruginosa (ceftazidime only), n. gonorrhoaea (ie gram negs); s. aureus, s. pneumonia, strep. pyogenes (ie gram pos, comparable to first gen, ceftazidime not so good, cefotaxime good for gram pos)
c) parenteral

21
Q

fourth gen cephalosporin a) examples b) useful spectrum
c) method of admin

A

a) cefepime
b) enterobacter, p. aeruginosa, n. gonorrhoaea; s. aureus, s. pneumonia, strep. pyogenes (same as third gen) + pseudomonas
c) parenteral

22
Q

fifth gen cephalosporin a) examples b) useful spectrum c) method of admin

A

a) ceftaroline
b) MRSA, VRSA, s. pneumoniae, h. influenzae, moraxella catarrhalis

23
Q

limitations of first gen to fourth gen cephalosporin?

A

no activity vs LAME = listeria, atypicals (mycoplasma, chlamydia, legionella), MRSA, enterococcus

24
Q

limitation of 5th gen cephalosporins?

A

no activity vs ESBL

25
Q

which gen of cephalosporin can cross CSF?

A

from 3rd gen onwards

26
Q

which gen of cephalosproin resistant to beta lactamase?

A

1st gen no; 2nd gen moderate; 3rd gen onwards good

27
Q

which gen of cephalosporin activity vs gram negs?

A

1st gen no; increases as go from 2nd gen to 4th gen

28
Q

clearance of cephalosporins?

A

all renal EXCEPT ceftriaxone (hepatic)

29
Q

caution with ceftriaxone?

A

do not mix with calcium containing product (ie ringers or hartmann solution) = will cause calcium precipitate

30
Q

adverse reactions to cephalosporins?

A
  1. hypersensitivity - cross reactivity with penicillin (if got penicillin allergy. NO to cephalosporin)
  2. GIT - diarrhoae (ie CDAD)
  3. thrombophlebitis - pls give slowly and in diluted form rotate infusion site
31
Q

Types of Carbapenems? (3)

A
  1. Imipenem (w/ cilastatin)
  2. Meropenem
  3. Ertapenem
32
Q

How are carbapenems administered?

A

IV

33
Q

How is imipenem prescribed? Why?

A

With cilastatin. Hydrolysed rapidly by DHP1 at the brush border of proximal renal tubule, thus DHP1 inhibitor cilastatin is added

34
Q

For carbapenems:
a) main target organisms
b) excretion

A

a) Imipenem: Gram Pos (esp strep (including penicillin resistant s. pneumoniae), staph (including penicillinase producing strains), enterococci), Gram Neg, ANaerobes, Pseudomonas; meropenem: similar to imipenem, with less activity vs gram pos, but more vs pseudomonas aeruginosa (those strains unable to be covered by imipenem); ertapenem: NO vs pseudomonas & enterococci

b) all renal

35
Q

types of infections to consider carbapenems?

A

1) nosocomial
2) intra-abdominal
c) skin
4) septicaemia

36
Q

which carbapenem to use in meningitis?

A

meropenem

37
Q

can use carbapenem for MRSA?

A

no

38
Q

adverse effects of carbapenem?

A
  1. GIT
  2. Rashes
  3. Neurotoxicity
  4. Hypersensitivity - cross reactivity with penicillin
39
Q

Example of a monobactem?

A

Aztreonam

40
Q

For monobactem,
a) Useful spectrum/type of infection
b) Method of administration
c) adverse effects
d) excretion

A

a) gram negs only, (including beta lactamase producing gram negs - enterobacter, p. aeruginosa, n. gonorrhoae, h. influenzae/ UTI, Lower respiratory tract infection, intra-abdominal, septicaemia

b) Parenteral

c) Skin rash + transaminasemia

d) renal

41
Q

Example of glycopeptide antibiotic?

A

Vancomycin

42
Q

For glycopeptide antibiotic,
a) Method of administration/ type of infections
b) target organisms
c) mechanism of action
d) excretion
e) adverse reactions
f) how might resistance come about?

A

a) IV + Oral (for CDAD + AAPMC)
b) Gram Positive Only (includes penicillin resistant + MSSA + MRSA)/ Osteomyelitis, Endocarditis, CDAD
c) Binds to D-Ala-D-Ala trminus of NAM component of peptidoglycan, thus intefering with transglycosylation of the cell wall precursor units
d) Renal
e) Thrombophlebitis, Red Man Syndrome (rash above nipple line due to histamine release when vanc is infused too rapidly - pls prolong duration of infusion to 1-2h), Nephrotoxicity, Ototoxicity (esp when use with another nephrotoxic or ototoxic agent)

Cat B Pregnancy for Oral; Cat C for parenteral

f) enterococcal resistance - substitute D-ALa fpr D-lactate or D-serine, reducing vanc binding affinity; S. aureus may have reduced susceptibility to vanc

Antibiotics (3 decks)

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