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Inhibitors of Cell Wall synthesis Flashcards

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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?

Study These Flashcards
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?

Study These Flashcards
A
  1. Surgical prophylaxis

2. Rarely DOC for any infections

25
Cephalosporin 2nd generation: what kind of bacterial coverage do they have? Activity against? weak against?
``` 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
Cephalosporin 2nd generation: | Clinical applications?
- sinusitis, otitis and lower respiratory tract infections. | - Cefotetan and cefoxitin: used for abdominal and pelvic infections therapy and prophylaxis.
27
Cephalosporin 3rd generation: High activity towards?*** DONOT cover?
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
3rd generation (ceftriaxone) DOC for:
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
3rd generation (ceftazidine and cefaperazone)- clinical applications
Activity against Pseudomonas aeruginosa CefTAZ covers pseudomonAZ
30
Cephalosporin 4th generation:
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
Cephalosporin 4th generation: clinical applications
Cefipime Tx. of infections with susceptible organisms eg. UTI's, complicated intra-abdominal infections, febrile neutropenia
32
Cephalosporin 5th generation: | Unique*
Ceftaroline (General TARA) - Parenteral admin. only - ACTIVITY against MRSA!!* - similar spectrum of activity to 3rd generation
33
Ceftaroline - 5th gen. cephaloporine clinical applications:
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
Cephalosporins PK | - administration?
- 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
Cephalosporins: AE What do cefamandole and cefoperazone?
- 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
Carbapepenems
Imipenem, Meropenem | - Synthetic B-lactam antibiotics
37
Carbapenems:-clincal applications
DOC for: - enterobacter infections - extended spectrum B-lactamase producing Gram-negatives.
38
Carbapenems- Antibacterial spectrum
- 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
Carbapenems- PK
- 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
Carbapenems- AE
Allergic reactions* (partial cross reactivity with penicillin's) HIGH levels of impenem can cause seizures GI distress (nausea, vomitin , diarrhea)
41
MONOBACTAMs
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
Monobactam clinical applications
``` UTI's Lower Resp. tract infections Septicemia Skin/structure infections Intraabdominal infections Gynecological infections caused by susceptible Gram -ve bacteria ```
43
Monobactam PK
Mainly IV or IM can be given by inhalation in CF patients Penetrates CSF when inflamed Excreted primarily via urine
44
Monobactam AE
Little cross-hypersensitivity w/ other B-lactam abs* | Phlebitis or thrombophlebitis reported w/ IV use
45
Vancomycin (VAN)
Bacterial glycoprotein (D-ALA D-ALA) Bactericicdal *Acts against Gram +ve bacteria ONLY* *Effective against multi-drug resistant organisms (eg, MRSA, enterococci, PRSP)
46
Vancomycin MOA
Binds to D-ALa-D-Ala terminus of nascent peptidoglycan pentapeptide. - Inhibits bacterial cell wall synthesis and peptidoglycan polymerization.
47
Vancomycin resistance
Plasmid mediated changes in drug permeabiltity | - Modification of the D-Ala-D-Ala binding site (D-Ala replaced by D-lactate)
48
Vancomycin clinical applications
- 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
Vancomycin PK
Requires slow IV infusion (60-90 min) poor oral absorption Penetrates the CSF when inflamed 90-100% excreted by kidney
50
Vancomycin AE
- 'Red man' or 'Red neck' syndrome (infusion related flushing over face and upper torso) - Ototoxicity (drug accumulation) - Nephrotoxicity (drug accumulatio)
51
Daptomycin (police dept)
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
Daptomycin MOA
Novel mechanim - Binds cell membrane via calcium-dependent insertion of lipid tail - results in depolarization of cell membrane with K+ efflux--> cell death
53
Daptomycin clincal applications | AE
- 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
Bacitracin MOA
Unique mechanisms-->no cross resistance Interferes in late stage cell wall synthesis Effective against Gram-positive organisms Marked nephrotoxicity--> mainly topical use*
55
Fosfomycin
used or treatment of uncomplicated lower UTI's

Pharmacology (27 decks)

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