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20 Cards in this Set
- Front
- Back
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What are the natural penicillins best against?
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Penicillin are effective against streptococcus spp as well as N. meningiditis and N gonorrhoeae. They are also good against Clostridium spp (except C. difficile). They are NOT good against Staphylococcus spp since they make penicillinase.
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How do penicillins work?
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By interfering with cell wall synthesis by binding to and inhibiting PBPs. Inhibition of PBPs leads to inhibition of the final transpeptidiation step of peptidoglycan synthesis leading to cell death. Penicillins are bacteriocidal except against enterococcus (in which they are bacteriostatic against).
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Name 3 mechanisms of resistance that bacteria have against penicillin
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1. Bacteria make a beta-lactamase enzyme which hydrolyzes the amide bond of the beta-lactam ring.
2. Alter the structure of the PBP to decrease binding affinity of pencillin to the PBP. 3. Decrease the ability of the antibiotic to penetrate the outer membrane of the bacteria (gram negatives) |
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Name the penicillinase-resistant penicillins
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DONC + M
Dicloxacillin, Oxacillin, Nafcillin, Cloxacillin + methicillin Methicillin is used for MSSA (obviously not active against MRSA) |
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What is special about dicloxacillin?
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It is a penicillinase-resistant penicillin that can be taken orally.
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Name the route of elimination of the penicillins
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All of the penicillins are removed by the kidney except for three.
Nafcillin and Oxacillin are removed by the liver (and are NOT removed by the machine during hemodialysis) Pipercillin is eliminated by both the kidney and the liver. |
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Name the bacteria that penicillin G is still considered the drug of choice for
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Penicillin G is still considered to be a DRUG OF CHOICE for the treatment of infections due to Treponema pallidum (syphilis), Neisseria meningitidis, Corynebacterium diphtheriae, Bacillus anthracis (anthrax), Clostridium perfringens and tetani, viridans and Group Streptococci.
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Name the aminopenicillins and what they are used to treat
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Ampicillin and amoxicillin are used to treat infections due to Listeria monocytogenes and Enterococcus.
Complete list: HEPS H. influenzae, E. coli, Proteus mobilis, Salmonells spp |
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Name the carboxypenicillins and what they are used to treat.
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Ticarcillin + carbenicillin treat HEPS + MEPP
H. influenzae, E. coli, Proteus mobilis, salmonella spp + morganella spp , enterobacter spp, providencia spp, and PSEUDOMONAS AERUGINOSA ... the gram negatives |
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Name the Ureidopenicillins
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Piperacillin, mezolocillin, azlocillin
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What is the drug of choice for treating Pseudomonas aeruginosa?
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Piperacillin (a ureidopenicillin)is the most active penicillin for pseudomonas aeruginosa. You could also use tircacillin (a carboxypenicillin).
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Name the 3 most important beta lactamase inhibitor combinations
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Amoxicillin / Clavulanic Acid (augmentin)
Ampicillin / Sulbactam (Unasyn) Piperacillin / Tazobactam (Zosyn) |
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What is the benefit of B-lactamase inhibitor Combinations? And what are they best used against?
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B-lactamase inhibitors prevent the bacteria from destroying the penicillin, allowing the penicillin given (amoxicillin, ampicillin or piperacillin) to do its duty. These drugs are best used against beta-lactamase producing species as well as the anaerobe B. fragilis
They aren't useful against beta-lactamase induced strains (SPICE) |
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What is SPICE?
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SPICE =
Serratia marcescens P. aeruginosa Indole positive Proteus spp Citrobacter spp Enterobacter spp |
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What are the pharmacodynamics of penicillin?
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Penicillins display time-dependent killing and are effective only during the Time above the MIC. They have a half life of around 2 hours and must be given frequently.
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Penicillins are only bacteriostatic against enterococcus spp, how do you make them bacteriocidal?
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Bacteriocidal activity can be achieved against enterococcus by adding an aminoglycoside (gentamycin or streptomycin) to develop a bacteria murdering SYNERGY.
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Many penicillins are degraded by gastric acid and are unsuitable for oral administration and must be given paraenterally... what drug can be given orally?
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Dicloxacillin
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In what situation are penicillins able to enter the CSF?
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When the meninges are inflamed and high doses of parenteral penicillins are used.
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What penicillin has a high Na load... and what does this mean for patients?
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Tircacillin has a high sodium load (5.2 mEq) and should not be given to patients with renal or cardiac problems for obvious reasons.
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Natural penicillins are the drug of choice for infections due to:
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S. pneumoniae
other streptococci including S. pyogenes (bacteremia, endocarditis, meningitis) N. meningitidis Treponema pallidum (syphilis) Clostridium perfringens or tetani Actinomycosis |
