Term
| What does weakening of the bacerial cell wall result in? |
|
Definition
| Cell lysis. The cell takes on too much water and ruptures. |
|
|
Term
| In which two ways do penicillins weaken the bacterial cell wall? |
|
Definition
1. inhibit transpeptidases - disrupt synthesis of the cell wall
2. activation of autolysins - promote active destruction of the cell wall |
|
|
Term
| What are penicillin binding proteins (PBPs)? |
|
Definition
| Molecular targets of penicillins such as transpeptidases and autolysins |
|
|
Term
| What are three mechanisms for bacterial resistance to penicillins? |
|
Definition
1. inability of penicillins to reach their targets
2. inactivation of penicillins by bacterial enzymes
3. production of PBPs that have a low affinity for penicillins |
|
|
Term
| What makes gram negative cell envelopes more resistant to penicillins than gram positive cell envelopes? |
|
Definition
| Gram negative envelopes have three layers to the gram positive envelope's two. The third, outermost layer of the gram negative envelope is very difficult for penicillins to penetrate. |
|
|
Term
| What cleaves the beta-lactam ring and renders penicillin and other beta-lactam antibiotics inactive? |
|
Definition
| Beta-Lactamases (penicillinases) |
|
|
Term
| Which microbe is particularly resistant to penicillins? |
|
Definition
|
|
Term
| Which variety of staphylococcus aureus is resistant to methicillin? |
|
Definition
| methicillin resistant staphylococcus aureus (MRSA) |
|
|
Term
| What are the four major groups of penicillins? |
|
Definition
1. narrow-spectrum penicillins that are penicillinase sensitive
2. narrow-spectrum penicillins that are penicillinase resistant
3. broad-spectrum penicillins (aminopenicillins)
4. extended-spectrum penicillins (antipseudomonal pencillins)
|
|
|
Term
| Which penicillin is the most well known and most widely chosen? |
|
Definition
|
|
Term
| Which penicillins are classified narrow-spectrum penicillinase sensitive? Which species are they useful against? |
|
Definition
Penicillin G and Penicillin V
streptococcus, neisseria, many anaerobes, spirochetes, others |
|
|
Term
Which penicillins are classified narrow-spectrum penicillinase resistant? Which species are they useful against?
|
|
Definition
Methicillin, Nafcillin, Oxacillin, Dicloxacillin
staphylococcus aureus |
|
|
Term
| Which penicillins are classified broad-spectrum aminopenicillins? Which species are they useful against? |
|
Definition
Ampicillin, Amoxicillin
Haemophilus influenzae, Escherichia coli, Proteus mirabilis, enterococci, Neisseria gonorrhoeae |
|
|
Term
| Which penicillins are classified extended-spectrum antipseudomonals? |
|
Definition
Ticarcillin, Piperacillin
Same as broad-spectrum penicillins plus Pseudomonas aeruginosa, Enterobacter species, Proteus (indole positive), Bacteroides fragilis, many Klebsiella |
|
|
Term
What are the three salts Penicillin G is available in?
|
|
Definition
1. potassium penicillin
2. procaine penicillin G
3. benzathine penicillin G |
|
|
Term
| By which routes can Penicillin G be given? |
|
Definition
|
|
Term
| If a patient has a known penicillin allergy, what is the best medication to give them if antimicrobials are indicated? |
|
Definition
| erythromycin or vancomycin |
|
|
Term
| What is the principal adverse effect of penicillins? |
|
Definition
|
|
Term
| Are cephalosporins safe for a patient with a known allergy to penicillin? |
|
Definition
| They are generally contraindicated, as there is about a 1% chance of cross-allergy |
|
|
Term
| Why should patients with renal insufficiency be closely monitored and the dosage reduced? |
|
Definition
| Because penicillin is eliminated by the kidney and can accumulate to harmful levels in patients with renal insufficiency |
|
|
Term
| Why is Penicillin G not given orally? |
|
Definition
| Because it is unstable in stomach acid |
|
|
Term
| Which variety of penicillin G is released slowly via IM injection and produces prolonged antibacterial effects? |
|
Definition
|
|
Term
| Which penicillins are particularly useful against gram-negative bacilli? |
|
Definition
| broad-spectrum penicillins such as ampicillin and amoxicillin |
|
|
Term
| Which substances can be added to certain penicillins to increase their activity against beta-lactamase producing bacteria? |
|
Definition
| beta-lactamase inhibitors such as clavulanic acid |
|
|
Term
| What should penicillins never be combined with in IV solution? |
|
Definition
| aminoglycosides such as gentamicin |
|
|
