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Respiratory Medicine Midterm > Beta Lactam Abx and cell wall synthesis inhibitor 2 - Fitzpatrick > Flashcards

Beta Lactam Abx and cell wall synthesis inhibitor 2 - Fitzpatrick Flashcards

1
Q

Cephalosporins have MOA and resistance similar to _

A

other beta lactams.

  • variable degradation by beta lactamase
  • clearance by renal excretions
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2
Q

All Gen1-3 cephalosproins are ineffective and lack activity against which pathogens?

A
  1. Listeria monocytogenes
  2. Legionella
  3. Atypical mycoplasma
  4. MRSA
  5. Enteroccoci
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3
Q

what are the 1st gen cephalosporins

A

Cefazolin and cephalexin

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4
Q

Which 1st gen cephalosporin can be given IV/IM; which one can be given PO? what are their distinctive indication?

A
  1. Cefazolin = Parenteral, IV, IM = penetrates well into bone
  2. Cephalexin = PO = 2x daily for pharyngitis
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5
Q

1st gen cephalosporins is useful against which agents? Not useful against?

A
  • Gram (+) cocci, strep and staph aureus.

Not active against: MRSA, MRSE, enterococci

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6
Q

what is the main clinical use of 1st gen cephalosporin?

A

Surgical prophylaxis if skin flora are likely pathogens; soft tissue and skin infection due to s. aureus, s pyogenes

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7
Q

What are the main 2nd gen cephlosporins?

A
  1. Cefoxitin (IV, IM) ( active against anaerobes e.g. b fragilis)
  2. Cefotetan (IV, IM) ( active against anaerobes e.g. b fragilis)
  3. Cefaclor (PO) - serum sickness in kids
  4. Cefuroxime axetil (PO)- poor substrate for beta lactamase
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8
Q

What is the main distinction between 1st gen and 2nd gen cephlosporins?

A

2nd gen is less active than 1st gen agents vs gram(+) organisms; enhanced activity against gram (-) e.g. ecoli, klebsiella, h influenza, moraxella cattharalis, proteus

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9
Q

what is the main clinical use of 2nd gen?

A

if facultative gram (-) bacteria and anaerobes are likely pathogens, e.g. Intra-abdominal and gynocological sepsis, surgical prophylaxis for intra-abdominal and colorectal surgery

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10
Q

What are the main 3rd gen cephlosporins?

A
  1. Ceftriaxone
  2. Cefotaxime
  3. Cetazidime
  4. Cefaperazone
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11
Q

What distinctions do the 3rd gen cephalosprins have?

A

ALL Parenteral

  1. Ceftriaxone: penetrates CSF and bone. used for Gonorrhea. Biliary clearance
  2. Cefotaxime: enters CSF; useful fo rmeningitis due to H influenza, s pneumonia, N meningitidis
  3. Cetazidime: active vs pseudomonas aeruginosa
  4. Cefaperazone: disulfiram like alcohol intolerance; active against pseudomonas
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12
Q

How do 1st gen and 3rd gen cephalosporins compare?

A

3rd gen is comparable to 1st gen vs S.aureus, s pneumonia, s pyogens.
- 3rd gen is enhanced activity against gram (-) rods, enteric organism

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13
Q

Because Ceftriaxone (3rd gen cephalosporin) has excellent distribution into CNS, It is recommended for therapy of _

A

Peinicillin-resistant gonorrhea, Lyme disease involving CNS or joints, meningitis due to ampicillin-resistant H. influenza, and meningitis in kids
- cleared via biliary excretion

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14
Q

Becuase cefotaxime has excellent CNS distribution, it is useful against _

A

bacterial meningitis frmo covered organism- H. influenza, s pneumonia, N meningitis and gram (-) enteric bacterial.
- Cleared via renal tubular secretion

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15
Q

Ceftazidime is particularly active against _ when the first line abx for this infection is resistant. Must be given in combo with _

A

pseudomonas. Ceftazidime is given in combo with an amyiinoglycoside (tobramycin) for treatment of serious P.aeruginosa

Anti-pseudomonas is first line. If infection is resistant to those abx and/or if pt is allergic to penicillin then use this.

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16
Q

What are some distinctive characteristics of 4th gen cephlosporins like cefepime?

A
  • Activity is greater or equal to cefotaxime vs gram(-), H influenza, N gonorrhea, N meningitidis
  • Excellent penetration into CSF
  • Activity is comparable to ceftazidime for pseudomonas
17
Q

If 1st line, and cetazidime are both resistant to pseudomonas what can be given?

A

Cefepime (4th gen cephalosporin)

18
Q

What AE are associated with 4th gen cephalosporins?

A
  • Hypersensitivity (immediate type I anaphylaxis or delayed type IV rash)
  • disulfiram- like reaction (nausea, flushing, HA w/alcohol consumption)
19
Q

Cephalosporins should not be used in pts with recent _

A

severe hypersensitivity rxn to a penicllin

20
Q

The disulfiram-like reaction seen as an AE to cehlosporins results from an inhibition of what enzyme? Causes build up of what product?

A

Aldehyde dehydrogenase. builds up acetaldehyde

21
Q

due to the methylthiotetrazole side chain of cefotetan and cefaperazole, these should be avoided in pts taking what other drug?

A

warfarin or pts with coagulation abnormalities.

MTT causes reduction in Vit K producing bacteria in GI tract–> hypoprothrombinemia and bleeding

22
Q

Name a monobactam drug

A

aztreonam

23
Q

Aztreonam is useful against what organisms?

A
  • ONLY active against Gram (-) rods such as Klebsiella, psudomonas, serratia.

NOT useful for gram+ or anaerobes

24
Q

What are some distincive characteristics of aztreonam?

A
  • MOA: binds to PBP 3 of gram(-) rods
  • substitute for extended spectrum penicillin or gen 3/4 cephalosporins if these are contraindicated cuz of hypersenstivity
  • safe alternative for aminoglycosides in elderly or renal impairment
  • synergistic with aminoglycosides parenteral IV, IM
25
Q

A severely ill hospitalized pts needs empirical abx for several bacteria, including gram (-) and (=), and MRSA. what is a good option?

A

Cabapenems such as Imipenem/cilatatin. These guys are THE BROADEST spectrum abx available.

Can treat gram(+) like enterocococus faecalis and listeria; Gram (-) like H influenza, gonorrhea, enterobacteriacease and pseudomonas); anaeroboes like B fragilis. NOT degrade d by beta lactamase
- Given IV with excellent penetration into tisues and fluid including CNS with inflamed meninges.

26
Q

What AE are associated with carbapenems?

A
  • Hypersensitivity and rahs (caution in pts with penicillin allergy)
  • CNS tox - seizures, confusion
  • NEPHROTOXICITY - imipenem.
27
Q

Imipenem is a nephrotoxin and thus is always used with _

A

Cilastatin which is a renal dipeptidase inhibitor, NOT a beta lactamase inhibitor

28
Q

Vancomycin is used under what condition?

A
  • penicillin hypersensitivity

- Narrow spectrum: gram+ cocci including MRSA, PRSP (pen resistant strep pneumo)

29
Q

Erythromycin is used under what conditioin?

A
  1. Penicillin hypersensitivity

2. Narrow spectrum: gram + and beta lactamase secreting staph aureus for BUT NOT MRSA or PRSP

30
Q

Under what condition is clindamycin used?

A

Used with penicillin to decrease toxin synthesis in life threatening streptococcal toxic shock and necrotizing fasciitis

31
Q

When is Tigecycline used?

A

Broad spectrum including: MRSA and VRE (vanco resistant enterococcus)

32
Q

when is Linezolid used?

A
  • VRSA and VRE

Respiratory Medicine Midterm (7 decks)

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