penicillins and cephalosporins and carbapenens Flashcards
What was the first mass-produced antibiotic?
Penicillin.
How do penicillins destroy bacteria?
They weaken the bacterial cell wall, causing the bacteria to take up excessive water and lyse (burst).
What is responsible for the antibacterial activity of penicillins?
The β-lactam ring.
Are penicillins effective against bacteria that are not growing?
No, they only work on bacteria undergoing growth and division.
What type of bacteria are penicillins mainly active against?
Gram-positive bacteria.
How are penicillins distributed in the body?
They are widely distributed to tissues but only a small amount enters the cerebrospinal fluid (CSF).
How are penicillins excreted?
Nearly all are excreted by the kidneys.
What is the half-life of most penicillins?
Short half-lives.
Why are penicillins one of the most common causes of drug allergies?
The immune system can recognize penicillin as foreign and trigger an allergic reaction.
What are two major ways bacteria develop resistance to penicillins?
- Inability to reach targets (altered cell wall structure) 2. Inactivation by bacterial enzymes (penicillinases or β-lactamases).
What is the function of β-lactamases?
They break the β-lactam ring, making penicillin ineffective.
How do β-lactamase inhibitors help penicillins?
They block β-lactamases, allowing penicillins to remain effective.
Name three β-lactamase inhibitors.
Clavulanic Acid, Tazobactam, Sulbactam.
What effect do penicillins have on oral contraceptives?
They decrease the efficacy of oral contraceptives.
What are the types of penicillin allergies?
- Immediate (within 30 mins) 2. Accelerated (1-72 hours) 3. Delayed (days to weeks).
What should be done if a patient has a severe penicillin allergy?
Administer epinephrine and provide respiratory support.
What is cross-sensitivity, and which drug class has cross-sensitivity with penicillins?
Cross-sensitivity means an allergy to one drug increases the risk of an allergy to another. Cephalosporins can cause cross-reactions with penicillins.
What organ function should be monitored when giving penicillins?
Kidney function (renal impairment risk).
What electrolyte imbalances can high-dose PCN G potassium or PCN G sodium cause?
Hyperkalemia, dysrhythmias, and hypernatremia.
Why should aminoglycosides and penicillins not be mixed in the same IV?
Penicillins inactivate aminoglycosides when mixed together.
What is the role of probenecid in penicillin therapy?
Probenecid delays excretion of penicillins, keeping the drug in the body longer for a stronger effect.
What are key nursing considerations for penicillins?
- Watch for allergic reactions. 2. Take PenV, Amoxicillin, and Amoxicillin/clavulanate with meals. 3. Take other penicillins with 8 oz of water before/after meals. 4. Use additional contraceptive methods. 5. Complete the full prescription.
Are penicillins safe for pregnancy and lactation?
Generally safe.
What is the most widely used group of antibiotics?
Cephalosporins.
What type of antibiotics are cephalosporins?
Beta-lactam antibiotics, similar to penicillins.
Can cephalosporins be given to patients allergic to penicillin?
Yes, if the allergy is mild, but caution is needed.
What enzyme can destroy cephalosporins?
Beta-lactamase (cephalosporinases).
Which generations of cephalosporins are more resistant to beta-lactamase?
3rd, 4th, and 5th generations.
Are cephalosporins more effective against gram-positive or gram-negative bacteria?
Mainly effective against gram-positive bacteria.
Are cephalosporins bactericidal or bacteriostatic?
Bactericidal.
How are cephalosporins usually administered?
Parenterally (IM/IV).
Are cephalosporins toxic?
Low toxicity.
Which cephalosporin is active against MRSA?
Ceftaroline (5th generation).
What are common adverse effects of cephalosporins?
Allergy/anaphylaxis, cross-sensitivity with penicillin, bleeding (Cefotetan, Ceftriaxone), thrombophlebitis, renal insufficiency, pain at injection site, pseudomembranous colitis (C. diff risk).
Which cephalosporins increase the risk of bleeding?
Cefotetan, Ceftriaxone.
Why do cephalosporins increase the risk of C. difficile infections?
They have a broader spectrum, which disrupts normal gut flora.
What is the disulfiram reaction?
A reaction to alcohol + cephalosporins, causing flushing, nausea, vomiting, headache, sweating, dizziness, vertigo.
Which cephalosporin should NOT be mixed with calcium?
Ceftriaxone.
What drug delays excretion of cephalosporins, prolonging their effect?
Probenecid.
Nursing considerations for cephalosporins?
Take full course, take with food, store PO suspension in the fridge.
Are cephalosporins safe in pregnancy/lactation?
Generally safe.
What types of infections are carbapenems used for?
Serious infections (pneumonia, peritonitis, UTIs).
What are common adverse effects of carbapenems?
Allergy/hypersensitivity, GI effects (nausea, vomiting, diarrhea), superinfection (oral thrush, black furry tongue, vaginal yeast infections), colitis.
Name two carbapenems and their routes.
Imipenem (IV), Meropenem (IV).
Why should carbapenems be used cautiously in patients with renal impairment?
They are excreted by the kidneys and can accumulate in renal failure.
How do carbapenems affect valproic acid levels?
They reduce valproic acid levels, increasing the risk of breakthrough seizures.
Are carbapenems safe in pregnancy and lactation?
Use caution.
