Antibiotics (Exam V) Flashcards
What color do gram + bacteria stain with? Why is this?
- Purple-Blue (Techoic acid stains to the peptidoglycan)
What makes up the cell wall in bacteria?
In which bacteria is this cell wall much bigger?
- Peptidoglycan
- Gram+ bacteria
What color do gram - bacteria stain with?
What characteristics do gram- bacteria have?
- Reddish-orange
- Second outer membrane on top of a thinner cell wall
- Gram - bacteria have lipopolysaccharides in their outer membrane.
What occurs if too many gram - bacteria are killed off too quickly?
Why is this?
- Endotoxic Shock Syndrome
- Massive release of lipopolysaccharides that are converted into endotoxin.
What shape do gram + bacteria often have?
What about gram - bacteria?
- Gram + = spherical (cocci)
- Gram - = rods (everything else)
Differentiate bactericidal & bacteriostatic.
Bactericidal = kills bacteria
Bacteriostatic = prevents replication/growth
What is the most broad spectrum antibiotic class?
Why are these safer for humans?
- Ribosome Protein Synthesis Inhibitors
- Inhibit ribosomes 50S & 30S that humans don’t have.
What types of ribosomes do bacteria have?
- 50S & 30S (& 70S)
What types of ribosomes do humans have?
- 40S, 60S, & 80S
What structure is highlighted in red below?
β-lactam ring
How do β-lactam containing ABX’s inhibit cell wall synthesis?
- The β-lactam ring binds & blocks the enzymes that cross link the peptidoglycans that form the wall.
What drug is indicated by 1 on the figure below?
Penicillin
What drug is indicated by 2 on the figure below?
Cephalosporin
What type of bacteria do cell wall inhibitors work best on?
Gram +
What type of bacteria do cell membrane disruptors work best on?
Gram -
What is the most common drug allergy that exists?
- Penicillin allergy (urticaria, redness, etc.)
What are carbapenems useful for?
What are they the drug of choice for?
- β-lactamase bacteria & when CNS penetration is needed.
- Enterobacter (drug of choice)
What drug is good for penicillin resistant gram + bacteria (MRSA)?
How does it work?
- Vancomycin
- Binds to amino acids & prevents cross-linking of peptidoglycans.
What adverse reactions can occur from vancomycin?
- “Red-neck” Syndrome - neck flushing from histamine release
- Ototoxicity
- Nephrotoxicity
- Chills/fever
How do cell membrane disruptors work?
- Act as detergents essentially. Bind to phospholipids in membrane & create pores.
Can Polymixin be used systemically to treat infections? Why or why not?
- Last resort for resistant gram - strains
- Very neuro & nephro toxic
What drug classes are protein synthesis inhibitors?
- Tetracyclines
- Macrolides
- Aminoglycosides
- etc.
What kind of structure do tetracyclines have?
Are they bacteriostatic or bactericidal?
- 4-ring structure
- Bacteriostatic
What is the biggest side effect of tetracyclines when used with adults?
Why is this?
- N/V/D & gastric upset.
- Very broad spectrum & can destroy normal intestinal microbiota
Why are tetracyclines not given to children?
- Abnormal bone development
Name the two macrolides discussed in lecture. What advantage does one have over the other?
- Erythromycin
- Azithromycin (short course, 4-5 days)
What drug, discussed in lecture, binds to bacterial RNA polymerase?
- Rifamycin
How do Fluoroquinolones work?
What characteristics do these drugs have?
- Inhibition of DNA gyrase
- Excellent gram - activity
- Good gram + activity
Which drugs are bacterial DNA/RNA synthesis inhibitors?
- Rifamycin
- Fluoroquinolones (Cipro, Levaquin, & floxins)
Which drugs are inhibitors of folic acid synthesis?
- Sulfonamides
- Trimethoprim
What is the mechanism of action of bacterial folic acid synthesis inhibitors?
- Prevent conversion of PABA into DHF (dihydrofolic acid) → → folic acid.
What are sulfonamides often used for?
What are they often used with?
- Pneumocystitis & toxoplasmosis
- Often paired with Trimethoprim
What antifungals need to be known?
- Imidazole
- Amphotericin
- Lamisil
What three antiprotozoan agents need to be known?
- Quinine
- Hydroxychloroquine
- Metronidazole (Flagyl)
What is metronidazole used for?
Giardia & trichomoniasis
What are the side effects of metronidazole?
- Black “hairy” tongue (can last a year)
- Birth defects
- Cancer
What drug is used to treat river blindness roundworm?
- Ivermectin
How does bacterial antibiotic resistance develop?
Describe extrachromosomal mutation.
- Chromosomal mutation
- Extrachromosomal mutation (f-plasmid forms f-pilli with another bacteria thus transferring its resistance.
How does premature termination of antibiotics propagate antibiotic resistance?
- Highly resistant bacteria take longer to be killed by antibiotic so if stopped early then the highly resistant ones are the only ones left that can reproduce.
What can be used for a horrible C-diff infection to restore normal intestinal flora?
- Fecal Transplant.
