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Module II > Cell Wall Synthesis Inhibitors > Flashcards

Cell Wall Synthesis Inhibitors Flashcards

1
Q

Beta Lactam structure

A

Thiazolidine ring attached to a B lactam ring that carries a secondary amino group

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2
Q

Pencillin MOA

A

PCN is a natural analog of D-ala-D-ala. PCD binding proteins (PBP’s) enzymes that remove terminal alanine to crosslink with neighboring peptide
PCDs inhibit this transpeptidation by covalently binding to PBP’s, blocking transpeptidation and inhibiting peptidoglycan synthesis within the bacterial cell wall
Leads to bacterial cell lysis and death
Bactericidal

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3
Q

Classes of PCN

A

Natural PCN
B lactamase resistant PCNs
Extended spectrum: amino-penicillins
Extended Spectrum: antipseudomomal penicillins

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4
Q

Natural penicillins

A

Penicillin G

Penicillin V

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5
Q

B-lactamase resistant penicillins

A

Methicillin
Nafcillin
Oxacillin
Dicloxacillin

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6
Q

Extended spectrum: amino-penicillins

A

Ampicillin

Amoxicillin

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7
Q

Extended spectrum antipseudomomal penicillin

A

Carbenicillin
Ticarcillin
Piperacillin

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8
Q

Penicillin G

A

natural PCN
Na or K
IV

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9
Q

Penicillin V

A

natural penicillin

PO

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10
Q

Benzathine Penicillin G

A

natural PCN

IM-long acting

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11
Q

Natural PCN spectrum of activity

A

streptococci, neisseria meningitidis, treponema pallidum, enterococcus faecalis.

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12
Q

Penicillinase-resistant Penicillins (penase-stable penicillins)

A

Methicillin (prototype)
Dicloxacillin (PO)
Nafcillin (im, IV, po)

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13
Q

Penicillinase resistant PCN spectrum of action

A 
s. aureus, staph epidermidis, penicillinase producing, streptococci but NOT:
MRSA
MRSE
Enterocci
Gram - organisms
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14
Q

Aminopenicillins

A

Extended spectrum. Includes:
Ampicillin (PO, IV, IM)
Amoxicillin (PO)
Spectrum: Gram +, streptococci, enterococcus faecalis, listeria monoctytogenes, treponema pallidum. Extended gram -: h. flu, some ecoli and proteus mirabilis.
NOT: klebsiella, pseudomonas, little staph coverage, NOT MRSA, MRSE

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15
Q

Antipseudomonal PCNs

A

extended spectrum.
Carboxypenicillins: Carbenicillin (PO) and Ticarcillin (IM, IV)
Ureidopencillins: Piperacillin
Spectrum: Expanded gram - to include p. aeruginosa, E. coli, serratia, proteus mirabilis and enterobacter, kelbsiella pneumonia. Gram +: streptococci, not as good as PCN. Poor staph, NOT MRS, NOT good for enterococci

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16
Q

Penicillin Resistance

A
  1. Inactivation of B lactamases
  2. Modification of target (PBP)
  3. Impaired Penetration
  4. Efflux
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17
Q

Inactivation of B-lactamase

A

Most common. B lactamase breaks a bond in the B lactam ring of PCN to disable the molecule. Bacteria with this enzyme can resis the effects of PCN and other B lactam antibodies

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18
Q

Alteration in target PCN binding proteins

A

Alteration in target PBPs. Reduced affinity-can overcome with very high concentrations. Resistance in one organism may result from replacements of its PBP with PBO from resistant organism. MRS; streptcoccus pneumoniae and enterococci-penicillin.

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19
Q

PCN resistance by impaired permeability

A

Permeability barrier preventing penetration of antibiotic-gram - organisms.
Can down regulate porins or not make
not so critical by itself; important with b-lactamase
efflux pump - gram - organisms

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20
Q

Penicillins Absorption

A

Natural PCN: oral–poor; PCN-V more acid stable. Parenteral: PCN G usually given IV. PCN G procaine needs to be cautioned with an allergy to procaine. Penicillin G benzathine–delay absorption, low serum level sustained >7 days, used for B hemolytic step and treponema pallidum
PCN-ase resistant: nafcillin poorly absorbed PO, usually given IV. Dicloxacillin: acid stable, given on an empty stomach.
Aminopenicillins: Amoxicillin PO, can be given with food. Ampicillin, food decreases rate and extend of absorption, usually only given IV
Anti-pseudomonal–carbenicillin PO. Others IV/IM

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21
Q

PCN Distribution

A

Protein binding: nafcillin 90%, PCN G 60%, others less
adequate distribution into MOST tissues and fluids; sputum and milk 3-15% of serum; eye, prostate poor.
Poor penetration into cerebrospinal fluid when BBB intact: both passive transport and active transport out of CSF along with other organic compounds
Poor entry into CSF, difficulty crossing BBB; hydrophilic and active transport out
“Adequate” CSF concentrations 3-5% penetration attained during inflammation
CSF: probenecid–inhibits transport out of CSF; uremia–organic cmpds accumulate in CSF compete for transport; can accumulate and cause seizures
All cross placenta; risk category B

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22
Q

PCN Elimination

A

Primarily renal for most, both glomerular filtration (10%) and tubular secretion (90%) (probenecid inhibits)
half-life < 1hr (except benzathine PCN)
severe renal insufficiency t½ up to 10 hrs
Significant non-renal elimination for a few agents, no adjustment in renal insufficiency:
Nafcillin: primarily biliary
Oxacillin, diclox, clox: both renal and biliary

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23
Q

PCN G Clinical Use

A

Infections caused by Streptococci (S pneumoniae, MIC < 0.1 mcg/ml, viridans group streptococci), including upper and lower respiratory infections (pneumonia), arthritis, endocarditis, septicemia, meningitis

  • *meningococcus meningitis
  • *Syphilis (Treponema pallidum - DOC for all stages and forms) **Oral anaerobes (peptococcus, peptostreptococcus) and clostridia
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24
Q

PCN V Clinical Uses

A

Strep pharyngitis

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25
Q

Benzathine PCN Clinical use:

A

syphilis

Single injection to treat beta-hemolytic strep pharyngitis

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26
Q

Penicillinase-resistant PCN’s Clinical Use

A

Infections caused by Staph aureus or Staph epidermidis

NOT MRSA or MRSE, not enterococcal infections

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27
Q

Aminopenicillins Clinical Use

A

Used to tx otitis media, upper respiratory tract infections, sinusitis, meningitis
Infections due to susceptible strains of Haemophilus influenzae, Proteus mirabilis, and E coli
DOC for Strep Grp B, uncomplicated enterococcus UTI, Listeria monocytogenses (+AG) , Lyme disease
Oral anaerobes

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28
Q

Antipseudomonal PCN’s Clinical Uses

A

For serious infections caused by Gr (-) bacteria: bacteremias, pneumonias, bone, skin, intra-abdominal, gynecologic, infections following burns and UTI due to organisms resistant to PCN-G and ampicillin, especially Pseudomonas aeruginosa

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29
Q

Benzathine PCN Dose

A

**Given IM

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30
Q

PCN G Dose

A

**Given IV

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31
Q

PCN V Dose

A

250 – 500mg PO bid, tid, qid

** Given PO

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32
Q

Dicloxacillin

A

125 - 500mg q6h, PO*

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33
Q

Nafcillin Dose

A

1-2 gm q4-6h IV**

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34
Q

Amoxicillin dose

A

500mg q8h PO or 875mg q12h
Peds: UD=usual dose: 40-45 mg/kg/d div q12h or q8h HD=high dose: 80-90 mg/kg/d div q12h or q8h raised because of strep resistance

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35
Q

Ampicillin dose

A

250-500 mg q6h PO; 1-2 gm q3-4hr IV

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36
Q

Piperacillin Dose

A

3-4gm IV q4-6h (12 gm/day for most organisms, but for Pseudomonas 18-24 gm/day

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37
Q

B-lactam inhibitors

A

Clavulanic acid, sulbactam, tazobactam
No antimicrobial activity, acts as a bodyguard
Inhibit many but not all bacterial betalactamases; protect hydrolysable PCN’s against inactivation by these enzymes
Goal is to extend spectrum of activity for the companion beta lactame

38
Q

Examples of B-lactam inhibitors

A

Fixed combos:
Amoxicillin + Clavulanic acid 125 mg = Augmentin PO
Ampicillin + Sulbactam = Unasyn (IV)
Ticarcillin + Clavulanic acid 100mg = Timentin (IV)
Piperacillin + Tazobactam = Zosyn (IV)
** Enhanced activity against beta-lactamases produced by s. aureus (Not MRSA), h. flu, e. coli, klebsiella pneumonia, n. gonorrhoeae, salmonella, shigella
**Inhibit chromosomal B-lactamases: legionella, bacteroides, branhamella
*no enhanced activity against AmpC B-lactamases

39
Q

Spectrum of Action with B-lactamase inhibitor

A

expands coverage of parent PCN. good against s. aureus, staph epidermidis (NOT MRSA, MRSE), strep, ok for enterocci. proteus, e. coli, klebsiella penumoniae, h. flu, moraxella, catarrhalis
NOT PSEUDOMONAS

40
Q

Dosing with B lactamase inhibitor

A

Augmentin: 875/125 bid PO; 500/125 or 250/125 tid PO
Zosyn: 2.25gm = Pip 2g, Tazo 250mg; 2.275 Pip 3g, Tazo 375mg; 4.5gm Pip = 4g, Tazo 500mg. Given IV q6h

41
Q

Cephalosporins Classification/Spectrum of Action

A

More stable to beta-lactamase than PCN; produced by cephalosporium mold.
MOA: like PCN

42
Q

First Gen Cephalosporins

A

Cephalothin
Cefazolin (Ancef, Kefzol) Parenteral; surg prophylaxis; skin infections not caused by MRSA
Cephalexin (Keflex) Oral
Cepharadine

43
Q

Secondary Gen Cephalosporins

A 
Cefaclor
Cefuroxime
Cefonicid
Cefoxitin
Cefotetan
44
Q

Third Gen Cephalosporins

A 
Ceftriaxone
Cefotaxime
Ceftzoxime
Cefixime
Cefdinir
Ceftazidime
Cefpodoxime
Cefditoren
45
Q

Fourth Gen Cephalosporins

A

Cefepime

46
Q

MRSA Activity Cephalosporins

A

Ceftaroline

47
Q

Cephalosporins First Gen Spectrum of Action

A

S. aureus, NOT MRSA, streptococci–aerobic and anaerobic; E. coli, K. pneumoniae, P. mirabilis
Resistant: enterococci sp, MRSE< MRSA, p. aerugenosa, b fragilis

48
Q

First Gen ceph clinical use

A

Cefazolin used for surgical prophylaxis

Cephalexin used for UTI, cellulitis, skin and soft tissue infections, mastitis

49
Q

Second Gen Ceph Oral agents:

A

Cefaclor (ceclor)
cefuroxime axetil (Ceftin)
Cefprozil (Cefzil)

50
Q

Secon Gen Ceph parental agents

A

Cefuroxime (Zinacef)
Cefotetan (Cefotan)
Cefoxitin (Mefoxin)

51
Q

Second Gen Ceph spectrum of action

A

Most important: stretpcocci (aerobic and anaerobic) less than G1, but varies by drug; m. catarrhalis, klebsiella better than G1
Cefuroxime, cefaclor: h. flu but not serratia or b. fragilis
Cefoxitin/cefotetan: bacteroides frafillis and some serratia, less against h. flu
*NOT MRSA, MRSE, ENTEROCCI, P. AERUGENOSA

52
Q

Second Gen Ceph clinical uses

A

PO for sinusitis, otitis media, LRI
Surgical prophylaxis for “dirty” surgeries–GI, hysterectomy: cefoxitin, cefotetan
Peritonitis or diverticulitis: cefoxitin, cefotetan

53
Q

Third Gen Ceph oral agents

A

Cefixime (Suprax)
Cefpodoxime (Vantin)
Cefibuten (Cedax)
Cefdinir (Omnicef)

54
Q

Third Gen ceph parenteral agents

A

Ceftazidime (Fortaz)

Ceftriaxone (Recephin)

55
Q

Third gen ceph B. fragilis group

A

Cefotaxime (Claforan)

Ceftrizoxime (Ceftizox)

56
Q

Third gen ceph spectrum of action

A

Neisseria gonorrhea: ceftriaxone, cefixime
expanded activity for most enterobacteriaceae (e. coli, klebsiella, serratia)
p. aeruginosa–limited to ceftazidime ‘
PCN reistant streptococcus pneumoniae–ceftrixaone or cefotaxime
some b. fragilis limited to ceftaxime
*NOT enterococci sp, listeria, MRSA or MRSE

57
Q

Third Gen ceph Clinical use

A

Respiratory, UTI, meningitis—crosses BBB
Ceftriaxone 125mg IM or cefixime 400mg x 1 for n. gonorrhea
pseudomonas infections
serious infections in hospital patients
intraabdominal infection

58
Q

Fourth Gen ceph

A

Cefepime (Maxipime) – parenteral

59
Q

Fourth gen ceph spectrum of action

A

streptococci–better than G2, G3
Gram - organisms like G3
p. aeuruginosa like ceftazidime
Resistant: enteroccia MRSA, MRSE, listeria monocytogenes

60
Q

Fourth Gen ceph clinical use

A

like G3,, ? less effect on SPICE B-lactamase induction

61
Q

Cefaroline (Teflaro)

A

New IV celphalosporin with activity against MRSA; other microbial coverage similar to ceftriaxone.
MOA: binds to penicillin-binding proteins to inhibit cell wall synthesis; high affinity to PBP2a (encoded by MedA gene in MRSA)
Use: skin and skin structure infections; not established for PNA tx.

62
Q

Cephalosporins Pharmacokinetics

A

Distibution: Ceftazidime or cefepime are DOS for meningitis caused by pseudomonas. MICs are sufficiently low; CSF concentration are higher
Elimination: Renally eliminated >7-% via active tubular secretion and GFR. EXCEPT ceftriaxone–biliary elimination
T1/2 for most = 2 hrs except CEFTRIAXONE = 8 HOURS

63
Q

Cephalosporin Dosing

A

IV: Cefazolin: 500 mg to 2 gm IV, IM q8h
Ceftriaxone: 500mg-2g IV, IM w/ lido q24h
Cefepime: 1-2g IV q12h

PO: Cephalexin: 250-500mg q6hr or 500mg q12h

64
Q

PCN and ceph hypersensativitiy

A

both usually tolerated well
PCN hypersens most common–5-8%, but only 5-10% have reaction with reexposure
Ceph: in pts w/ pcn, ~7%, w/o 1-2%
4 types of hypersensitivity

“ampicillin rash” 9% of pts–not true allergy

65
Q

Type I sensativity: IgE mediatied

A

Immediate: <1%, anaphylaxis
Accelerated: 1-72 hrs, uticaria
Avoid ceph in pts with recent h/o immediate reaction to PCN

skin testing can help prevent or predict sensativity

66
Q

Type II: cytotoxic IgM and IgG antibody mediated

A

hematologic
+coombs test (3%)
small # of pts develop hemolytic anemia

67
Q

Type III: Immune complex of PCN and IgG or IgM

A

1-7% of patients
Serum sickness (fever, malaise, uticaria)
usually 6-10 days after start of PCN, 2nd, 3rd gen ceph

68
Q

Type IV: T-cell mediated; delayed/late

A

48+ hours, dermatologic maculopapular rash

most common with PCN G

69
Q

PCN and ceph ADRs

A

Diarrha (esp amp, amox, ceftriaxone, cefoperozone)
IM-pain, sterile abscess, redness
IV: phlebitis, pain, burning, redness
Hepatitis: rare. *Pseudocholelithiasis (biliary sludging) – seen with ceftriaxone
seizures–rare
potassium load (PCN G)
sodium load (ticarcillin)
N-methyltetrazole ring–cefotetan
antabuse reactions–MTT-containing cephs
Jarisch-hexheimer reaction–PCN G with syphilis

70
Q

PCN-ceph Drug interactions

A

Probenecid-blocks secretion at renal tubules
Aminoglycosides-PCN
Wafarin: dicloxacillin and nafcillin reduce warfarin effect, cephs with MTT side chain

71
Q

Ceftaroline

A

Teflaro
pharmacokinetics: primarily rental elimination half life=2.6 hours
ADR: N/D, rash, coombs conversion
Preg Cat B

72
Q

Carbapenems Drugs

A

Imipenem/cilastatin (Primaxim)
Meropenem (Merrem IV)
Ertapenem (Invanz)
Doripenem (Doribax)

73
Q

Carbapenems Spectrom of Action

A

Gram +, Gram -, enterobacteria, p.aerginosa
NOT ertapenem
B fragilis

74
Q

Carbapenem Resistance mechanisms

A

Porin loss

Carbapenemase

75
Q

Carbapenem clinical use

A

Reserve for serious infections caused by resistant organisms
UTI, septicemia, GYN infections, intra-abdominal
High PCN resistant pneumococci and enterobacter

76
Q

Carbapenem pharmacokinetics

A

Usually IV
Wide distribution–inflamed meninges
cilastatin inhibits renal dehydropeptidase–decreased hydrolzation of imipenem in kidney
primarily renal; reduce dose in renal insufficiency

77
Q

Carbapenem ADRs

A

hypersensativity reactions: rash, fever, pruritis, up to 50% cross sensativity with PCN (higher than cephs)
seizures
GI

78
Q

Monobactam

A

Aztreonam (Azactam) IV (also IM and inhalation)

elimination is primarily renal

79
Q

Monobactam spectrum of action

A

Aerobic Gram - Only

e. coli, klebsiella, p. mirabilis, serratia

80
Q

Monobactam clinical use

A

in pts with renal insufficiency, pcn or ceph allergy. not thought to cross react hypersensativities
use not well definied

81
Q

Vancomycin MOA:

A

Glycopeptide; Binds to d-ala-d-ala in Stage 1, prevents further growth of peptidoglycan and cross-linking

82
Q

Vancomycin resistance

A

modification of the D-ala-D-ala site; terminal D-ala replaced by D-lactate

83
Q

Vancomycin SOA

A

Bacteriocidal for Gram +
MRSA, c. diff
NO Gram - activity

84
Q

Vancomycin Pharmacokinetics

A 
GIVE IV
Not absorbed PO
IM creates sterile abscess, not absorbed\
Elimination: renal--1/2=4-8 hours normal
adjust dose in renal insufficiency
85
Q

Vancomycin clinical use

A

Serious infections such as sepsis, endocarditis, MRSA, MRSE

86
Q

Vanco ADRs

A

Red Man syndrome–histamine release–infuse slowly (1-2hrs)
Sterile abscess with IM
Ototoxicity–serum level >60 mcg/mL
Nephrotoxicity

87
Q

Vanco Dose

A

Adults: 15-20mg/kg/dose q8-12h

Desired levels: trough 15-20mcg/mL, peak 20-50

88
Q

Daptomycin

A

(Cubicin)
First cyclic lipopeptide antimicrobial agent
Use: skin infections caused by s. auerus including MRSA and strep
Excreted renally; reduce dose when CrCl <30ml/min q48 hours
ADE: anemia, myopathy
IV ONLY

89
Q

Fosfomycin

A

Use: tx of uncomplicated UTI in women caused be e.coli or e. faecialis
Mix 3gm in warm water

90
Q

Bacitracin

A

Topical use only

91
Q

Cycloserine

A

Use: TB

92
Q

Ceftobiprole

A

new cephalosporin, MRSA coverage, dosed 8 hrs

Module II (4 decks)

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