Antibacterials - Penicillins Flashcards
What are benefits of using bacterialcidal antibiotics?
Better for immunocompromised patients and difficult to penetrate locations such as meningitis, endocarditis, and bone infections.
What does time-dependent killing mechanism mean?
The antibiotics work the best when they are above the MIC for at least 50% of the treatment time for best effects.
– Beta Lactams –
How does concentration dependent killing work?
Where the higher the peak concentration from the start of treatment correlates to better treatment due to the drug getting into the bacteria initially and eliciting effects long afterwards.
– Aminoglycosides –
How does the killing based upon concentration x time and area under the curve?
The area underneath the curve over a 24 hour period, doesn’t depend on peak dose or time over MIC.
– Quinolones –
What are the types of drugs that target the bacterial cell wall?
B-Lactams, Vancomycin, Fosfomycin, and Bacitracin
What are unique properties of B-Lactams?
Bactericidal. Most effective on growing bacteria.
Binds PBP, preventing cross-linking of pepidoglycan.
Short Half-Lives
What is an intrinsic property of resistance by Gram Negative bacteria?
Outer Cell wall that has porins only allowing in certian molecules that are small enough.
How can B-lactamase cause resistance for bacteria and neighboring bacteria?
B-Lactamase is primarily made by gram negative, but also some gram positive bacteria and released extracellularly preventing the concentration gradient of antibiotics from getting too high at the cell and surrounding cells.
What kind of dosing is required for B-Lactams?
Time-Dependent, thus more frequent doses to maintain above the MIC.
What are unique chacteristics of Penicillins?
Limited CSF penetration, but more can penetrate when inflammation of meningitis.
Short Half Lives
Renal Elimination into urine
What drug is primarily used for non-B-lactamase gram positive anaerobic bacteria?
Penicillin G – IV/IM Only
Penicillin V - Oral
What is the first line of therapy for syphilis and alternative therapy for lyme disease?
Penicillin G and V
What are the three most common modes of resistance to B-lactams?
B-Lactamase
Altered PBP
Porins preventing entry
What class of bacteria is Penicillin most effective on?
Streptococcus, not pneumonae though
Works very well on Neisseria Meningiditis
What Penicillin would be used for B-lactamase producing Straph Aureas?
Oxacillin
What are extended spectrum penicillins that include both gram positive and negative bacterium?
Ampicillin
Amoxicillin
Only if B-lactamase negative
What is the drug of choice for Otititis Media for peds?
Amoxicillin
What drug is used for Lyme disease if the patient is pregnant or breast feeding?
Amoxicillin
What are the differences between Ampicillin and Amoxicillin?
Amoxicillin – better for oral dosing, more absorbed
Ampicillin – IV for meningitis, and PO for GI infections (due to less being absorbed)
What penicillins are used for broad spectrum gram negative to treat pseudomonas?
Ticarcillin and Piperacillin
What would be used if Pseudomonas was resistant to Ticarcillin?
Piperacillin. Covers Pseudomonas and Klebsiella including organisms resistant to Ticarcillin.
What are the most common side effects of Penicillin?
Rash, Diarrhea, Enterocolitis, Fever, Elevated liver enyzmes, hemolytic anemia, and Anaphylaxis
What is a problem with taking any type of antibiotics?
They can all cause diarrhea due to killing the natural GI flora increasing chances of enterocolitis and C.Diff
How can you predict a pencillin allergy?
PrePen is a skin test used to test for penicillin allergy, which has a 95% accuracy.
If you are allergic to one penicillin what does that mean for the rest of the penicillins?
If you are allergic to one, there is a significantly higher chance of being allergic to another.
Less chance with the synthetic penicillins
What are the two B-lactamase inhibitors?
Clavulanic Acid
Tazobactam
–Both bind irreversibly to most B-lactamases–
What is the benefit of combining B-lactamases with regular penicillins?
This can overcome resistance and successfully rid the bacteria.
