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Pharmacology > Antibacterial: Cell Wall Synthesis Inhibitors > Flashcards

Antibacterial: Cell Wall Synthesis Inhibitors Flashcards

1
Q

list the cell wall synthesis inhibitors

A
  • B-lactam antibiotics
    • penicillins
    • cephalosporins
    • carbapenems
    • monobactams
  • Vancomycin
  • Daptomycin
  • Bacitracin
  • Fosfomycin
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2
Q

CWSI are inactive against? and require?

A
  • Inactive against organisms without peptidoglycan cell wall eg. mycoplasma, protozoa, fungi, viruses
  • Require actively proliferating bacteria (cell wall synthesis must be occurring)
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3
Q

describe B-lactamase

A
  • Bacterial enzymes that hydrolyze B-lactam ring
    • resist effects of penicillins eg. Staph aureus
  • B-lactamase inhibitors
    • protect penicillins from inactivation via binding and inactivating B-lactamase
    • Clavulanic Acid, Sulbactam, Tazobactam
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4
Q

what is the target site for B-lactam antibiotics

A
  • Penicillin-binding proteins (PBPs)
  • bacterial enzymes (transpeptidases) involved in cell
  • wall synthesis = target site for B-lactam antibiotics
  • resistance = PBP mutations
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5
Q

B-lactam MOA

A
  • Bactericidal
  • Inhibit last step in peptidoglycan synthesis through binding to PBPs
  • Activate autolytic enzymes to initiate cell death
  • Bacteria eventually lyse due to activity of autolysins and inhibition of cell-wall assembly
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6
Q

Penicillin G clinical application

A
  • Mostly used for Gram + organisms
  • Given IV
  • Commonly used for:
    • Syphilis (benzathine penicillin G)
    • Strep infections
    • Susceptible pneumococci
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7
Q

Penicillin V

A
  • more acid stable than G (can give orally)
  • used for mild-moderate infections eg. pharyngitis, tonsilitis, skin infections (caused by Strep)
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8
Q

Anti-Staph Penicillins

A
  • Nafcillin
  • Methicillin (inactive against MRSA)
  • Oxacillin
  • Dicloxacillin
  • ONLY Penicillin resistant to B-lactamase
    • NO NEED FOR B-lactamase inhibitor
  • TXT for B-lactamase-producing staphylococci
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9
Q

Ampicillin, Amoxicillin

A
  • Similar to Penicillin G but with Gram negative activity
  • Given w/ B-lactamase inhibitor
  • Clinical use:
    • acute otitis media
    • streptococcal pharyngitis
    • pneumonia
    • skin infections
    • UTIs
  • AE: maculopapular rash
  • AE for Ampicillin only: Pseudomembranous colitis
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10
Q

Good penicillin for children?

A

Amoxicillin

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11
Q

Anti-Pseudomonal Penicillins

A
  • Carbenicillin, Ticarcillin, Piperacillin
  • Against Gram negative and positive bacilli
  • Active against Pseudomonas Aeruginosa
  • Treats moderate-severe conditions of susceptible organisms
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12
Q

Penicillin AEs

A
  • GI disturbances (eg, diarrhea)
  • Pseudomembranous colitis (ampicillin)
  • Maculopapular rash (ampicillin, amoxicillin)
  • Interstitial nephritis (particularly methicillin)
  • Neurotoxicity (epileptic patients at risk)
  • Hematologic toxicities (ticarcillin)
  • Neutropenia (nafcillin)
  • Hepatitis (oxacillin)
  • Secondary infections (eg, vaginal candidiasis)
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13
Q

Positive Coombs Test?

A

Penicillin G, V

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14
Q

Carbapenems

A
  • Doripenam, Ertapenam, Meropenam, Imipenam
  • “DIME antibiotics for 10/10 infections”
  • Very broad → Gram (-), (+), anaerobe, aerobe
  • Not active against MRSA or carbapenamse producing bacteria (klebsiella)
  • Ertapenam = not active against P. Aureginosa
  • Imipenam given with Cilastatin to prevent nephrotoxicity - inhibits dehyropeptidase I (high levels of imipenam = seizures)
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15
Q

Aztreonam

A
  • Monobactam
  • Gram negative only
  • given to penicillin allergic patients
  • Little AE’s, no cross resistance with penillin
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16
Q

Vancomycin MOA/resistance

A
  • binds to D-Ala-D-Ala terminus
  • Resistance: D-Ala-D-LAC, plasmid-mediated changes
17
Q

Vancomycin Clinical use

A
  • Gram positive only
  • Effective against MRSA
  • Given to severely penicillin allergy patients
  • Vancomycin + Amingoglycoside = txt infective endocarditis + PRSP
  • Oral for pseudomembranous colitis, or staph enterocolitis
18
Q

Vancomycin AEs

A
  • slow IV infusion 60-90 min otherwise RED-MAN syndrome
  • Nephrotoxicity
  • Ototoxicity
  • Thrombophlebitis
19
Q

Daptomycin MOA

A
  • Ca2+ dependent insertion of lipid tail → depolarization → k+ efflux → cell death
20
Q

Daptomycin

A
  • Cidal, IV only
  • Resistant Gram +ve (MRSA, VRE, VRSA - b/c of novel MOA)
  • Surfactant inhibits drug → NOT given for pneumonia
  • Clinical use: complicated skin/structure infections by s. aureus
21
Q

Daptomycin AE

A

Elevated creatinine phosphokinases - myopathy

(don’t take with statins)

22
Q

Bacitracin

A
  • Gram positive
  • Unique MOA → no cross resistance
  • HUGE molecule → mainly topical for burns/skin wounds
  • AE: Nephrotoxicity
23
Q

Fosfomycin

A
  • Gram negative and positive
  • MOA: Inhibits enolpyruvate transferase in early cell wall synthesis (all others = late)
  • Oral
  • Treats: uncomplicated lower UTI’s

Pharmacology (19 decks)

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