Antibiotics Flashcards
Exam 4
List the antibiotics that work by inhibiting cell wall synthesis. Describe their MOA
- Penicillin, ampicillin, and amoxicillin
- Cephalosporins
- Carbapenems
- Vancomycin
ß-lactam ring attaches to the enzymes that cross-link peptidoglycans and prevent cell wall synthesis (Gram +)
Which of the cell wall synthesis inhibitors can penetrate the CNS?
Carbapenems
Which antibiotic is considered the “drug of last resort”? What is it used for?
Vancomycin
- Alternative to PCN resistant bacteria (MRSA)
Adverse reactions of vancomycin
Tissue irritation
Ototoxicity
Nephrotoxicity
“Red neck” syndrome
What are the 2 antibiotics that work by disrupting the cell membrane? What is their MOA?
- Polymyxin and Daptomycin
- Polypeptide antibiotics
- Act as detergents – bind to phospholipids
- Best action – Gram (-)
What is Daptomycin used to treat?
- Better for Gram (+)
- Skin infections, bacteremia
What is the triple antibiotic?
OTC Topical
- Polymyxin – cell membranes (Gram (-))
- Neomycin – bacterial protein synthesis
- Bacitracin – cell wall synthesis (Gram (+))
List the antibiotics that inhibit protein synthesis. What is their MOA?
Tetracycline
Macrolides (Erythromycin, Azithromycin)
Neomycin
- Attack bacterial cells without significantly damaging animal cells - wide spectrum
_______ have the widest spectrum of activity of any antibiotics
Tetracyclines
What is the main side effect of antibiotics that inhibit protein synthesis?
GI
What are the antibiotics that work by inhibiting nucleic acid synthesis? What is their MOA?
Rifamycin family - binds to bacterial RNA polymerase
Fluoroquinolones (Ciprofloxacin) - Inhibit DNA gyrase (bacterial)
What are fluoroquinolones used to treat?
- UTI, RTI
- Bone and joint infections
- ADR
- Excellent Gram (-) activity
What are the 2 antibiotics that work by inhibiting folic acid synthesis?
Sulfonamides, trimethoprim
What are the 2 ways antibiotics can function to inhibit folic acid synthesis?
- Competitive inhibition
- Incorporated into important molecules
What do folic acid synthesis inhibitors treat?
Pneumocystis, toxoplasmosis
What is the MOA of ketoconazol (imidazoles)?
Cream for cell membrane inhibition
What are the 2 antifungals?
Ketoconazole
Lamisil
What is Hydroxychloroquine used to treat? What kind of drug is it?
Malaria, antiprotozoan agent
What is Metronidazole (flagyl) used to treat?
Giardia, Trichomonas
What are the side effects of Metronidazole (flagyl)?
- Birth defects
- Cancer
- Black hairy tongue
What is Ivermectin used to treat?
- river blindness roundworm
- COVID-19?
What is Permethrin used to treat?
lice
What is the most common drug allergy?
penicillin
What is Niclosamide used to treat?
Tapeworms
What are the differences between gram positive and gram negative bacteria?
Gram positive – teichoic acid
Gram negative
- Additional outer membrane
- Contains lipopolysaccharide (LPS)
List the five general properties of antimicrobial agents
- Selective Toxicity
- Spectrum of Activity
- Modes of Action
- Side Effects
- Resistance of Microorganisms
What are the 5 MOA of antibiotics?
- Cell wall inhibitors
- Cell membrane disrupters
- Protein synthesis inhibitors
- Nucleic acid synthesis inhibitors
- Folic acid synthesis inhibitors
What is the prototype macrolide?
erythromycin
List the major adverse effects of the penicillins and the cephalosporins.
- Hypersensitivity - Most common drug allergy; can cross-react with similar antibiotics
- Allergic reactions - Anaphylactic shock (0.05%), Skin rash (<1%), Oral lesions, Hemolytic anemia, Interstitial nephritis, GI upset, Infusion pain
Identify key questions in deciding which antibiotic to use for which illness.
Questions
- Clinical findings?
- Microbiologic diagnosis?
- Narrow spectrum?
- Single versus combination
- Optimal dose for patient?
- Response to treatment?
- Adjunctive measures?
Selection
- Concomitant disease states?
- Prior adverse drug reactions?
- Impaired elimination or metabolism?
- Age
- Pregnancy status
- Genetics
Discuss the effects of premature termination of antibiotics.
Differentiate spectrum of activity and selective toxicity.
Spectrum of activity: how broad or narrow its target is
selective toxicity: describes the ability of a drug to harm a target microorganism without significantly harming the host organism
Describe mechanisms underlying the resistance of bacteria to beta-lactam antibiotics.
Bacteria develop resistance to beta-lactam antibiotics primarily through the production of enzymes called beta-lactamases, which break down the beta-lactam ring of the antibiotic, rendering it ineffective
Discuss how disruption of normal microflora may be problematic.
It throws off the delicate balance of beneficial bacteria in the body, allowing potentially harmful bacteria to overgrow and leading to various health issues
