Exam 4 - Drugs That Weaken The Bacterial Cell Wall Flashcards
How do penicillins work?
*Bactericidal
They weaken the cell wall, causing bacteria to take up excessive water and rupture
What type of bacteria is penicillin more effective at killing and why?
Gram-positive bacteria because there are only two layers of cell envelope that is easily accessible for the penicillin
What are beta-lactamases?
Enzymes that render penicillin inactive
Bacteria can produce a large variety of these enxymes specific for penicillins (and other beta-lactam antibiotics)
How do bacteria become resistant to antibiotics, specifically penicillin?
Penicillinases (a type of beta-lactamase)
Classifications of penicillins
Narrow spectrum penicillins (pencillinase-sensitive)
Narrow spectrum penicillins (pencillinase-resistant)
Broad spectrum penicillins
Extended spectrum penicillins
Prototype penicillin
Penicillin G (Benzylpenicillin)
What type of bacteria does penicillin G kill?
Numerous gram-positive and some gram-negative organisms
What is the most common cause of drug allergy?
*Penicillins
If a pt has a penicillin allergy, what should you ask them?
What their reaction to it was
Mild or anaphylaxis
What should you do for a pt who says they have had a mild reaction to penicillin, vs. a history of anaphylaxis?
Mild: consider cephalosporin
*Anaphylaxis: avoid administration of penicillin or cephalospirin
Possible timings of penicillin allergy
Immediate (reaction in 2-30 mins)
Accelerated (reaction in 1-72 hrs)
Late (reaction takes days or weeks to develop)
What symptoms occur with anaphylaxis?
Laryngeal edema
Bronchoconstriction
Severe hypotension
*Treatment of anaphylaxis
*Epinephrine
*Respiratory support (if needed)
How to prevent a penicillin allergy
Skin testing
Drug interactions of penicillin
Aminoglycosides (may still be given together but cant be mixed in same IV bag)
Penicillin V
Probenecid
Penicillinase-Resistant Penicillins in the US
Nafcillin
Oxacillin
Dicloxacillin
What does MRSA stand for?
Methicillin-resistant staphylococcus aureus
Another name for broad spectrum penicillins
Aminopenicillins
Examples of broad-spectrum penicillins
Ampicillin (Principen)
Amoxicillin
Adverse effects of broad spectrum penicillins
Rash
Diarrhea
How can broad spectrum penicillins be administered?
PO
IV
Another name for Extended spectrum penicillins
Antipseudomonal penicillins
Example of extended spectrum penicillin
Piperacillin
Key points about penicillins
Bacteriocidal
Low toxic unless you’re allergic
*Most widely used group of antibiotics
*Cephalosporins
Structure of cephalosporins
Beta-lactam ring (similar to penicillin structure)
Key points about cephalosporins
Bactericidal
Low toxicity
How are cephalospirins typically administered?
Parenterally
How to cephalosporins work?
Bind to penicillin-binding proteins (PBP’s), disrupt cell wall synthesis, and cause cell lysis
Explain the generations of Cephalosporins
5 generations
Gen 1 &2 are more mild
Get stronger as you get to gen 5
3, 4, 5th gen more resistant than 1st and 2nd
What is 1st generation of cephalosporins used for?
Prophylaxis against infection in surgical patients
What are second generation cephalosporins used for?
More activity against gram-negative bacteria (used in combinations)
What are 3rd generations cephalosporins used for?
Highly effective against gram-negative organisms
*Able to penetrate to CSF in effective concentrations
*B/c of this, used to treat meningitis
What are 4th generation cephlosporins used for?
Healthcare and hospital associate pneumonias
Including those resistant to Pseudomonas
What are 5th generation cephalosporins used to treat?
Infections associated with MRSA
Examples of 1st generation cephalosporins
Cephalexin (Keflex)
Cefazolin (Ancef)
Examples of 2nd generation cephalosporins
Cefoxitin (Mefoxin)
Cefaclor (Ceclor)
Examples of 3rd generation cephalosporins
Ceftazidime (Fortaz)
Cefotaxime (Claforan)
Example of fourth generation cephalosporin
Cefepime (Maxipime)
Example of 5th generation cephalosporin
Ceftaroline (Teflaro)
Drug interactions with cephalosporins
Probenecid
Alcohol
Drugs that promote bleeding
Calcium
Ceftriaxone
Adverse effects of cephalosporins
Allergy - hypersensitivity, rash
Bleeding
Thrombophlebitis
What are carbapenems?
Beta-lactam antibiotics that have an extremely broad antimicrobial spectrum
And are *Not active against MRSA
Prototype Carbapenem
Imipenem (Primaxin)
Other types of carbapenems
Meropenem (Merrem IV)
Ertapenem (Invanz)
What is Imipenem (Primaxin) used for?
Gram pos and neg bacteria
Most effective beta-lactam antibiotic for use against *anaerobic bacteria
Adverse effects of carbapenems
GI interactions
Rash
How does Vancomycin work?
Inhibits cell wall synthesis (much stronger antibiotic)
Uses of vancomycin
*Severe infections only
MRSA
Staphylococcus epidermidis
C. Diff
Administration of vancomycin
IV (must be given slowly over an hour)
And now can be given PO
Adverse effects of Vancomycin
*Renal failure
Ototoxicity
*Red man syndrome
Thrombophlebitis (common)
Thrombocytopenia (rare)
Allergy
S/S that occur when Vancomycin is given too quickly
Flushing
Tachycardia
Hypotension
Antibiotic used only for gram negative aerobic bacteria
Class: Monobactams
Drug: Aztreonam (Azactam)
Administration of Aztreonam (Azactam)
Must be given IV or IM
Antibiotic used for VAP (vent acquired pneumonia)
Class: lipoglycoproteins
Drug: Telavancin (Vibativ)
Administration of Vibativ
IV
Adverse effects of Vibativ
Prolong QT interval
