Penicillins

What is the half life of most penicillins in all species?

0.5 to 1.2 hours

Who is credited with discovering Penicillin?

Alexander Flemming (in 1928)

Broad spectrum aminopenicillins include:

Ampicillin Amoxicillin Hetacillin

Amoxicillin + Clauvulanic acid =

Augmentin, Clavamox (Oral and parenteral)

Antibacterial spectrum of beta-lactamase resistant penicillins:

Beta-lactamase producing organisms

Broad spectrum antipseudomonal penicillins include:

Carbencillin Carbencillin indanyl Ticarcillin Azlocillin

Who are credited with isolating Penicillin G?

Chain and Flory (in 1940)

Beta-lactamse inhibitor compounds used in conjunction with penicillin treatment include:

Clavulanic acid Sulbactam Tazobactam

What dosage considerations should you remember to effectively use penicillins to treat a patient?

Concentration should be above MIC through duration of treatment and frequent administration or constant infusion is recommended

Antibacterial spectrum of amidinopenicillins:

E. coli Shigella Klebsiella Enterobacter

How are penicillins excreted from the body?

Excreted as an active compound through the kidneys. (Except Nafcillin) Active secretion through proximal convoluted tubule

Antibacterial spectrum of broad spectrum aminopenicillins include:

Haemophilus influenzae E. coli Proteus mirabilis Salmonella

Side-effects of penicillins include:

Hypersensitivity (allergic reaction), GI disturbance (oral penicillins), Hemolytic anemia and thrombocytopenia (less common), CNS excitement and ataxia may lead to death (high doses in horses)

What is the mechanism of action of Penicillins?

Inhibit cell wall synthesis

Do the beta-lactamase inhibitors inhibit beta-lactamase reversibly or irreversibly?

Irreversibly

Amidinopenicillins include:

Mecillinam and Pivmecillinam

Narrow Spectrum penicillinase resistant penicillins include:

Methicillin Nafcillin Oxacillin, CLoxacillin, Dicloxacillin

What is a L-form microorganism?

Microorganism that lives in the Loop of Henle Cell wall is not necessary due to osmolality

Should you mix penicillin with bacteriostatic medications?

No, it will inhibit penicillin's bactericidal effect since penicillin works best on bacteria undergoing replication

Can penicillins cross the blood brain barrier?

Not under normal body conditions, but if there is CNS inflammation it may cross.

What is the original penicillin called?

Penicillin G

Narrow Spectrum Penicillinase Sensitive Penicillins include:

Penicillin G Penicillin V Penethicillin

Which Penicillin G preparation has the longest duration?

Penicillin G Benzathine

Which Penicillin G preparation should not be used in milking cows but can be used it beef cattle?

Penicillin G Benzatine

Which Penicillin G preparation could interfere with the heart in horses if injected too quickly?

Penicillin G Porassium

What are the 3 main preparations of Penicillin G?

Penicillin G Potassium Penicillin G Procaine Penicillin G Benzathine

Which Penicillin G preparation can kill the animal if injected IV?

Penicillin G Procaine Procaine also extends half-life

What enzyme do bacteria use to inactivate penicillin?

Penicillinase (a beta-lactamase)

Extended spectrum penicillins include:

Piperacillin and Mezlocillin

What inhibits active secretion of penicillin?

Probenecid

Antibacterial spectrum of broad spectrum antipseudomonal penicillins include:

Same as broad spectrum aminopenicillins plus Enterobacter species Indole positive proteus (Not effective against those producing penicillinase

Antibacterial spectrum of penicillinase resistant penicillins includes:

Staphalococcus aureus

Antibiotic spectrum of Narrow spectrum penicillinase sensitive penecillins include:

Streptococcus sp, Niesseria sp, many aerobes (e.g., Clostridium and Fusobacterium), Spirochetes (e.g., Leptospira, Borrilia, and Tryponema), Pasteurella multicida, Corynebacterium, Listeria monocytogenes, and Actinobacillus

Beta-lactamace resistant penicillins includes:

Temocillin (modified Ticarcillin)

What is the important part of the chemical structure of penicillin that gives it the ability to fight bacteria?

The beta-lactam ring If the ring is opened, penicillin is inactivated

Can you describe in detail how penicillins inhibit cell wall synthesis?

They inhibit the formation of the peptidoglycan layer by inhibiting the transpeptidase enzyme and through the stimulation of autolysins by binding to penicillin binding proteins (PBPs). This leads to the rupture of the microorganism.

How is nafcillin excreted through the body?

Through bile, not the kidneys

Ticarcillin + Clavulanic acid =

Timentin (parenteral)

Ampicillin + Sulbactam =

Unasyn (parenteral)

Limitations of Penicillin G include:

Unstable in gastric acid Susceptible to Beta-lactamase Inactivity to Gram negative bacteria Short half-life

What is the eagle effect?

When high concentrations of penicillin diminish its affect on the microorganism due to self antagonism at the binding site on penicillin binding protein (PBP)

Are L-form microorganisms resistant to penicillin?

Yes, they have no cell wall so penicillin has no target

Poperacillin + Tazobactam =

Zosyn (human parenteral preparation)

Antibacterial spectrum of extended spectrum penicillins:

same as broad spectrum antipseudomonal penicillins with increased activity against Enterobacteriaceae (especially Klebsilla) and some anaerobes including Bacteriodes fragilis