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Pharmacology > Inhibitors of Cell Wall synthesis > Flashcards

Inhibitors of Cell Wall synthesis Flashcards

1
Q

Cell wall synthesis inhibitors

A 
B-lactams abs
- Penicillins
- Cephalosporins
- Carbapenems
- Monobactams
Vancomycin
Daptomycin
Bacitracin
Fosfomycin

require actively proliferating bactera (cell wall synthesis must be occuring)

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2
Q

Penicillin-binding proteins (PBP)-

A

bacterial enzymes involved in cell wall synthesis. Target site for B-lactam antibiotics.

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3
Q

Penicillin
MOA?
what king of organisms is it inactive against?

A
  1. Inhibits last step of peptidoglycan synthesis through binding to PBPs.
    - Penicillins also activate autolysin (bacterial enzyme) to initiate cell death by lysis and inhibiton of cell wall assembly.
  2. Inactive against organisms w/out peptidoglycan cell wall. eg. mycoplasma/ protozoa/ fungi/ viruses
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4
Q

Natural penicillins: Penicillin G

  1. what is it active against?
  2. What is t susceptible to?
A

Benzylpenicillin

  1. active against:
    - Most gram positive cocci (NOT STAPH)
    - Gram-postive rods (eg. Listeria/ C- perfringes)
    - Gram negative cocci (eg. Neisseria)
    - Most anaerobes (NOT BACTERIODES)
  2. Susceptible to inactivation by B-lactamases
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5
Q

What is the DOC for:
Syphilis
Strep infections (especially in prevention of rheumatic fever)
Susceptible pneumococci

A

Penicillin G

- Benzathine penicillin G for syphilis and Rheumatic fever prophylaxis.

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6
Q

Repository Penicillins are used for:

Mode of transmission is through:

A

Prolonging Penicillin G by increasing t1/2.
- Penicllin G procain
- Penicillin G Benzathine
Intramuscular not IV (risk of procaine toxicity)
- seldom used (increased resistance

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7
Q

Natural penicillins: Penicillin V
Administration?
DOC?

A

less sensitive ti Gram -ve bacteria than G
More acid stable (Can be given orally)
DOC for Strep throat
- employed orally for mild-moderate infections eg. pharyngitis/ tonsilits/ skin infections (caused by strep throat)

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8
Q

‘Antistaphylococcal’ penicillins
special trait:
First line tx for:

A 
Methilcillin
Nafcillin (Naf for staph)
Oxacillin
Dicloxacillin
- B-lactamase resistant
- Inactive against MRSA

First line for staphylococci endocarditis in patients w/out artificial heart valves.

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9
Q

Extended-spectrum penicllins

A

Ampicillin
Amoxicllin
Similar to penicillin G (+ gram negative activity)
susceptible to B-lactamases
activity enhanced w/ B-lactamase inhibitor

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10
Q

Amoxicillin special because

A

Highest oral bioavailabilty than other penicillins

also common ab prescribed for children an pregnancy

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11
Q

Ampicillin and Amoxicillin clinical appllications

A

Acute otitis media
streptococcal pharyngitis
pneumonia
skin infections
UTIs
- widely used to treat upper respiratory infections (H. Influenzae and S. pneumoniae)
- Prophylaxis against endocarditis during dental and respiratory tract procedures.

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12
Q

Ampicillin + aminoglycoside are used to treat

A

Enterococci

Listerial infections

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13
Q

Antipseudomonal Penicillins

Active against what type of organisms?

A

Carbenicillin
Ticarcillin (+ clavulinate B-lactamase inhibitor)
Piperacillin (+ Tazobactam)
Effective against many gram -ve and +ve bacilli
Often combined w/ B-lactamase inhibitor
Active against P. aeruginosa

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14
Q

Carbenicillin
Ticarcillin
Piperacillin
Clinical applications:

A
  • Pseudomonas aeruginosa treatment
  • Main clinical use= as an injectable tx. of Gram -ve’s

Treatment of moderate to severe infections of susceptible organisms (eg. uncomplicated and complicated skin/ gynecologic and intra-abdominal infections/ febrile neutropenia)

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15
Q

Penicillin + aminoglycoside

DOC for?

A

Synergistic
Penicillins facilitate movement of aminoglycosides through cell wall
- Never place in the same infusion fluid (form inactive complex)
DOC: Effective emperic tx. for infective endocarditis

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16
Q

Penicillin PK
- Oral absorption?
- Nafcillin oral absorption?
distribution?

A

Impaired by food
t1/2=30-60 mins (except for repository penicillins)
Nafcillin = erratic (not suitable for oral admin)

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17
Q

Penicillin PK
distributiontion?
Excretion?

A

All achieve therapeutic levels in pleural pericardial pertioneal synovial fluids and urine

Naficillin ampicillin and piperacillin achieve high levels in bile

levels in prostate and eye = insufficient
CSF penetration = poor (except in meningitis)

Excreted mostly in Kidney
Nafcillin = exception as primarily excreted in bile*

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18
Q

Penicillin AE

A

Hypersensitivity*
- Penicillic acid = major antigenic determinant
Gi disturbances (eg. diarrhea)*
Pseudomembranous colitis (ampicillin)*
Maculopapular rash (ampicilln/ amoxicillin)*
Interstitial nehritis (methicillin)
Neurotoxicity (epileptics at risk)
Hematologic toxicities (ticarcillin)
Neutropenia (naficillin)
Hepatitis (oxacillin)
Secondary infections (eg. Vaginal candidiasis)

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19
Q

B-lactamase inhibitors

MOA?

A

Clavulanic Acid
Sulbactam
Tazobactam

MOA: Bind to and inactivate most B-lactamsases
- do not have significant anti bacterial activity.

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20
Q

Cepahalosporins are considered inactive against?

A 
"CAMELL"
Enterococci
Listeria
Legionella
Chlamydia
Mycoplasma
Acinebacter
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21
Q

4th Gen. cephalosporins are similar to which other generations?
What similarities do they both share?

A

Similar to 1st gen. against gram +ve cocci and are also active against most gram -ve bacilli.

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22
Q

5th Gen. cephalosporins are similar to which other generations?
Whats unique about 5th gen?

A

Have similar spectrum to the 3rd gen.

They are unique in that they have activity against MRSA

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23
Q

Cephalosporin 1st generation:
what are they substitutes of?
What are they resistant to?
Activity against?

A

Cefazolin (FEZ), Cephalexin (FLEX)

  • Penicillin G substitutes
  • Resistant to staphylococcal penicillinase
  • Activity against gram positive cocci and P. mirabilis, E. coli and Klebsiella pneumoniae (PEK)
  • surgical prophylaxis
24
Q

Cefalozin is the DOC for?

What infections are 1st gen. cephalosporins DOC for?

A
  1. Surgical prophylaxis

2. Rarely DOC for any infections

25
Q

Cephalosporin 2nd generation:
what kind of bacterial coverage do they have?
Activity against?
weak against?

A 
Cefaclor, cefoxitin (FOX), cefotetan (tea cup), cefamandole
1. Extended gram -ve coverage 
2. Greater active against
HENS*
- H. Influenzae
- Enterobacter aerogenes
- Neisseria species
- Serratia
3. Weak against gram -ve.
26
Q

Cephalosporin 2nd generation:

Clinical applications?

A
  • sinusitis, otitis and lower respiratory tract infections.

- Cefotetan and cefoxitin: used for abdominal and pelvic infections therapy and prophylaxis.

27
Q

Cephalosporin 3rd generation:
High activity towards?***
DONOT cover?

A

Ceftriaxone*(axes), Cefoperazone, cefotaxime (axe), Ceftazidime(General TAZ) cefixime

  • high activity towards, enterobacteriae, H. Influenzae and Neisseria!!!
  • Enhanced activity towards gram -ve cocci.
  • ceftriaxone and cefotaxime usually active against pneumococci
  • DONOT COVER MRSA
28
Q

3rd generation (ceftriaxone) DOC for:

A

DOC for gonorrhea(intramuscular)
DOC for meningitis due to ampicillin resistant H. Influenzae!!
prophylaxis of meningitis in exposed people.
Tx. for lyme disease (CNS or joint infection).

29
Q

3rd generation (ceftazidine and cefaperazone)- clinical applications

A

Activity against Pseudomonas aeruginosa

CefTAZ covers pseudomonAZ

30
Q

Cephalosporin 4th generation:

A

Cefipime (General prime)

  • serious systemic infections with ab resistant organisms
  • Parenteral admin. only
  • wide antibacterial spectrum
  • Gram +ve activity of 1st gen. and Gram -ve activity of 3rd gen.
    eg. Enterobacter, Haemophilus, Neisseria, E. coli, Pneumococci, P. mirabilis and P. aeroginuosa
31
Q

Cephalosporin 4th generation: clinical applications

A

Cefipime
Tx. of infections with susceptible organisms
eg. UTI’s, complicated intra-abdominal infections, febrile neutropenia

32
Q

Cephalosporin 5th generation:

Unique*

A

Ceftaroline (General TARA)

  • Parenteral admin. only
  • ACTIVITY against MRSA!!*
  • similar spectrum of activity to 3rd generation
33
Q

Ceftaroline - 5th gen. cephaloporine clinical applications:

A

Skin and soft tissue infection due to MRSA particularly if gram -ve pathogens are co-infecting

  • community-acquired pneumonia (when first-line agents are unsuccessful).
34
Q

Cephalosporins PK

- administration?

A
  • Most administered parenterally except cephalxin, cefaclor, cefixime.
  • Only 3rd gen reach adequate levels in CSF
  • Mainly eliminated via kidneys (exceptions= ceftriaxone and cefoperazone excreted in bile.
35
Q

Cephalosporins:
AE
What do cefamandole and cefoperazone?

A
  • Allergic reactions (cross-sensitivity w/ penicillins can occur)
  • However, minor penicillin allergic patients often treated successfully w/ a cephalosporin
  • Pain at infection site (IM), Thrombophlebitis (IV)
    Superinfections (eg. c. difficile)

Cefamandole, cefoperazone and cefotetan contain methyl-thiotetrazole group, all can cause:

  • hypoprothrombinemia (Vit K1 admin can prevent)
  • disulfiram-like reactions (avoid alcohol)
36
Q

Carbapepenems

A

Imipenem, Meropenem

- Synthetic B-lactam antibiotics

37
Q

Carbapenems:-clincal applications

A

DOC for:

  • enterobacter infections
  • extended spectrum B-lactamase producing Gram-negatives.
38
Q

Carbapenems- Antibacterial spectrum

A
  • Resist hydrolysis by most B-lactamases
  • Very broad spectrum of activity**
  • Active against penicillinase-producing Gram-positive and negative organisms; aerobes and anaerobes; P. aeroginosa
  • Not active against Carbapenemase producing organisms* eg, carbapenem resistant enterobacteriaceae, carbapenem resistant Klebsiella.
  • Not active against MRSA**
39
Q

Carbapenems- PK

A
  • IV
  • Imipenem forms potentially nephrotoxic metabolite. Combining w/ enzyme inhibitor Cilastin (“keep it lasting with cilastin”) prevents metabolism thus prevent toxicity and increases availability.
40
Q

Carbapenems- AE

A

Allergic reactions* (partial cross reactivity with penicillin’s)

HIGH levels of impenem can cause seizures

GI distress (nausea, vomitin , diarrhea)

41
Q

MONOBACTAMs

A

Aztreonam (AZ-3M)

  • Aerobic (bellows) Gram-negative rods ONLY (including pseudomonas)
  • No activity against Gram-positive bacteria or anaerobes*
  • Resistant to action of B-lactamases (plasmid encode)
42
Q

Monobactam clinical applications

A 
UTI's
Lower Resp. tract infections
Septicemia
Skin/structure infections
Intraabdominal infections
Gynecological infections caused by susceptible Gram -ve bacteria
43
Q

Monobactam PK

A

Mainly IV or IM
can be given by inhalation in CF patients
Penetrates CSF when inflamed
Excreted primarily via urine

44
Q

Monobactam AE

A

Little cross-hypersensitivity w/ other B-lactam abs*

Phlebitis or thrombophlebitis reported w/ IV use

45
Q

Vancomycin (VAN)

A

Bacterial glycoprotein (D-ALA D-ALA)
Bactericicdal
Acts against Gram +ve bacteria ONLY
*Effective against multi-drug resistant organisms (eg, MRSA, enterococci, PRSP)

46
Q

Vancomycin MOA

A

Binds to D-ALa-D-Ala terminus of nascent peptidoglycan pentapeptide.
- Inhibits bacterial cell wall synthesis and peptidoglycan polymerization.

47
Q

Vancomycin resistance

A

Plasmid mediated changes in drug permeabiltity

- Modification of the D-Ala-D-Ala binding site (D-Ala replaced by D-lactate)

48
Q

Vancomycin clinical applications

A
  • Tx serious infections caused by B-lactam resistant gram +ve organisms eg MRSA
  • Tx of Gram +ve infections in patiens severely allergic to B-lactams
  • In combination with an aminoglycoside for emperical treatment of Infective endocarditis
  • In combination w/ an aminoglycoside for treatment of enterococcal endocarditis of PRSP.
  • Given ORALLY for the treatment of staphylococcal enterocolitis or antibiotic-associated pseudomembranous colitis (take a VAN to the METRO (metronidazole) when treating c. diff.)
49
Q

Vancomycin PK

A

Requires slow IV infusion (60-90 min)
poor oral absorption
Penetrates the CSF when inflamed
90-100% excreted by kidney

50
Q

Vancomycin AE

A
  • ‘Red man’ or ‘Red neck’ syndrome (infusion related flushing over face and upper torso)
  • Ototoxicity (drug accumulation)
  • Nephrotoxicity (drug accumulatio)
51
Q

Daptomycin (police dept)

A

Bactericidal

  • Effective against gram resistant Gram-postive organisms ( eg MRSA (ORSA), enterococci, VRE and VRSA)
  • Inactive against Gram -ve bacteria
  • Not effective in treatment of pneumonia, deactivated by pulmonary surfactant.
  • Depolarization
52
Q

Daptomycin MOA

A

Novel mechanim

  • Binds cell membrane via calcium-dependent insertion of lipid tail
  • results in depolarization of cell membrane with K+ efflux–> cell death
53
Q

Daptomycin clincal applications

AE

A
  • recommended for tx of severe infections caused by MRSA or VRE
  • Tx of complicated skin/structure infections caused by susceptible S. aureus
  • IV only
  • can accumulate in renal insufficiency
    AE:
    Constipation, Nausea, headache, insomnia
    Elevated creatnine phosphokinases (recommended to discontinue coadmin. of statins)
54
Q

Bacitracin MOA

A

Unique mechanisms–>no cross resistance
Interferes in late stage cell wall synthesis
Effective against Gram-positive organisms
Marked nephrotoxicity–> mainly topical use*

55
Q

Fosfomycin

A

used or treatment of uncomplicated lower UTI’s

Pharmacology (27 decks)

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