penicilin

Question 1

General Char of penicilin

Answer 1

Bactericidal
synergitic effect if added with aminoglycoside,

Resistance
develop Beta lactamase (penicilinase).
Change of PBP enzyme
Porins (pseudo)

Mechanism of action:
Bactericidal, penicilin interact with cytoplasmic membrane binding proteins (PBP) to inhibit transpeptidation reaction involved in cross linking.

Spectrum:

1. Narrow spectrum, beta-lactamase sensitive (Penicilin G and V).
2. Very narrow spectrum, beta lactamase resistant: nafcillin, methicilllin, oxacillin.
3. Broad spectrum, aminopenicillins, beta lactamase sensitive: ampicillin and amoxicillin.
4. Extended spectrum antipseudomonal beta lactamase sensitive: Ticarcillin and piperacillin.

Kinetics:
Eliminated via tubular secretions which is blocked by probenecid (due to low half life). dose reduction needed only in major renal dysfunction.
Nafcillin and oxacillin eliminated largely in bile.

Side effects include:

1. Hypersensitive reactions- 1-4.
2. Cross allergenicity between individual penicillins.
3. Interstitial nephritis
4. Gi distress, especially ampicillin.
5. Jarisch herheimer reaction in syphillis.

Total daily dose should be 3-4 doses a day.

CNS inflammation allows penetration of penicilins, otherwise the penetration is extremely low.

Question 2

1. Narrow spectrum, beta-lactamase sensitive (Penicilin G and V).

Answer 2

Penicilin G- IV Penicilin V- ORal

Question 3

what are the beta lactamase resistant penicilins?

Answer 3

nafcillin, methicillin, oxacillin, cloxacillin and dicloxacillin

Question 4

what are the extented spectrum penicillins?

Answer 4

aminopenicillins: ampicillin, amoxycillin
carboxypenicillins: carbencillin ticarcillin
ureidopencillin: piperacillin, mezlocillin, azlocillin

Question 5

what is the spectrum of basic penicillins:

Answer 5

Gram + Aerobic and anerobic=== YES
Gram - Aerobic +/-
Gram - Anerobic -

Gram +, aerobic: Staphy with no beta lactamase production:

1. streptococci.
2. enterococci,
3. pneumococcus.

Gram + bacteria, anerobic non beta lactamase producing anaerobes:
Clostridium and
actinomyces.

Gram - Cocci
Neisseria gonororrhea and meningtidis

Gram - rod: Limited activity

Atypical pathogens:
sprichotes (spirochetes).

Question 6

Penicilin resistant to Beta lactamase spectrum

Answer 6

Oxacillin cloxacillin, dicloxacillin, nafcillin are resistant to staphyloccocal beta lactamase
Baiscly antistaphylococcal penicillins.

Gram + Aerobic= yes, rest of the spectrum= NO.

Active against: Staphyloccocus, streptococcus, pneumococcus.

Question 7

Extended spectrum penicillins spectrum

Answer 7

like ampicillin, amoxicillin, cabencillin, ticarcillin, piperacillin, mezlocillin and azlocillin.
All subject to Beta lactamase hydrolses.
Enhanced ability to penetrate through G- outer membrane of gram negative rod bacteria (pseudomonall).

Gram + aerobs: +/-
Gram + anaerobic: +
Gram - aerobic: ++/-
Gram - Anaerobic: +

Active against:
Gram + aerobic:
Pneumococcus, enterococcus corynebacterium and listeria monocytogenes
Gram - bacteria, extended activity against: E. Coli, haemophylus influenza, proteus infections, salmonella shigella and

Pseudomonas:(Gram - rods, aerob),: ticarcillin and piperacillin.

Question 8

clinical indications of Penicillins (simple)

Answer 8

Tonsillitis, tonsillopharyngitis, erysipelas, toxic shock, endocarditis, gangrene gonorrhea lyme disease leptospirosis.

Question 9

clinical indication for beta lactamase resistant penicillins

Answer 9

staphyloccocus mainly (beta lactamase producting staphy).
NOT MRSA.

Question 10

extended spetrcum penicillins usage

Answer 10

upper and lower respraitory tract infection and urinary tract infections bacteriuria while pregnancy and more.
bacteriuria during pregnancy
complicated intraabdominal infections and complicated skin and soft tissue infections.

Question 11

beta lactamase inhibitors:

Answer 11

clavulanic acid, sulbactam and tazabactam which are combined with ampicillin, amoxcillin and piperacillin
Ampicillin+ sulbactam
Amoxicillin and clavulanic acid
Piperacillin and tazabactam