Antimicrobials Flashcards
Isoniazid (INH)
Anti-biotic
Inhibits synthesis of mycolic acid
Prophylaxis for mycobacteirum infections
Cotrimoxazole (Bactrim)
Anti-biotic
Inhibits folate metabolism
Mixture of sulfonamide and trimethoprim
***cillins - Penicillin, Methicillin, Amoxicillin, Nafcillin
Inhibit cell wall synthesis by covalently/irreversibly binding and inactivating transpeptidases (act as suicide substrates)
Penicillin: Syphilis
Nafcillin: MSSA
What was the first orally available penicillin?
AmOxicillin
Gram + bacteria have what 2 things in their cell walls?
Peptidoglycans, lipoteichoic acids
Gram - bacteria have what in their cell walls?
LPS
What enzyme do bacteria synthesize to resist penicillin?
Penicillinase aka beta-lactamase (opens the beta-lactam ring in penicillin)
How does penicillin work?
Covalently/irreversibly binds transpeptidases (rqd for cell wall sythesis) and inactivates them
Augmentin
Antibiotic - inhibits penicillinase
Amoxicillin + clavulanic acid
Zosyn
Antibiotic
Piperacillin + tazobactam (inhibits pencillinase)
Intensive care setting and covers both Gram + and - organisms
Are penicillins more effective against Gram + or Gram - bacteria?
Gram +
Cephalosporins (Cef***) - Cefazolin, Cefoxitin, Ceftriaxone, Cefepime
Anti-biotic - inhibits cell wall synthesis by irreversibly binding to transpeptidases
More resistant to beta-lactamases, has less hypersensitivity rxns, and more Gram (-) coverage
1st gen: MSSA, PEK
2nd gen: MSSA, HENPECK
3rd gen: community-acquired pneumonia, meningitis
Gram (-) Bacteria - PEKHEN
Proteus, E coli, Klebsiella, Haemophilus, Enterobacter, Neisseria
Gram (+) Bacteria - CLEPSS
Clostridium, Listeria, Enterococcus, Pneumococcus, Staph, Strep
Vancomycin
Anti-biotic
Inhibits cell wall synthesis - binds D-alanine and prevents transpeptidase enzyme for cross-linking
MRSA
**floxacins/Fluoroquinolones - Cipro/Ciprofloxacin and Moxifloxacin
Antibiotic - inhibit DNA gyrase
Community-acquired pneumonia
Newer generation drugs have less _____ coverage and more ____ coverage.
Less Gram +, more Gram -
Rifampin/Rifamycin
Inhibits bacterial RNA polymerase; also mitochondrial RNA polymerase
TB
**cycline - Tetracycline
Antibiotic - inhibit protein synthesis
Bacteriostatic vs. bactericidal
Stop bacterial growth vs. kill bacteria
Narrow spectrum vs. broad spectrum
Narrow spectrum - covers one or a couple bugs
Broad spectrum - covers lots of bugs
What antibiotic can cause anaphylactic rxn due to allergies?
Penicillin
What cocktail is used for post-exposure prophylaxis for HIV?
2+1 HAART (same one used for treatment of HIV patients)
Where do aerobic bacteria tend to live in the body?
Airway, lungs (oxygen-rich)
Where do anaerobic bacteria tend to live in the body?
GI tract, GU tract (oxygen-poor)
What is the drug of choice to treat syphilis? A. Cephalosporins B. Penicillin G C. Ciprofloxacin D. Bactrim E. Azithromycin
B
What type of infection is more likely to be drug resistant? Community-acquired or nosocomial?
Nosocomial (hospital-acquired) infection
How do bacteria become resistant to drugs?
- Degrade the drug (penicillinase)
- Change/mutate targets - altered penicillin binding proteins
- Up-regulate efflux pumps
- Alter membrane/decrease permeability
- Transfer resistance genes from other cells (plasmids)
- All of the above
All of the above
What organisms are most likely responsible for community acquired pneumonia? What is the treatment?
Strep pneumoniae or Staph aureus (MSSA)
Treat: Cephalosporins (3rd gen) + Azithromycin OR Moxifloxacin
What is synergy? Give example.
When certain combinations of antibiotics work better than the drugs alone.
Ex: Penicillins + Aminoglycosides (**mycins) - inhibit both cell wall synthesis and protein synthesis
What would be a reason for prescribing antibiotics to someone with a viral infection?
Prevent opportunistic infections - especially in elderly or immunocompromised
Why do bacteria synthesize coagulase?
converts fibrinogen –> fibrin, coats bacteria, prevents phagocytosis
Why do bacteria synthesize catalase?
converts toxic H2O2 –> H20, bacteria can multiply happily
Why do bacteria perform hemolysis?
Lyses blood & immune cells – more difficult to clear infection
Why do bacteria synthesize collagenase, hyaluronidase?
spread by digesting extracellular matrix
Why do bacteria synthesize toxins?
to get more nutrients, water, electrolytes, etc. from host cells
What types of drugs should you use to treat an ulcer?
- PPI - to raise pH and decrease acid secretion
- Antibiotics - to kill H pylori
- Bismuth - to coat and heal GI surface
Why does one have to stop taking aspirin before surgeries?
It’s a blood thinner
What are two drug-resistant infections?
MRSA - methicillin-resistant Staph aureus
VRE - Vancomycin-resistant enterococci
Quinupristin / Dalphopristin
Anti-biotics
Last resort treatment for VRE
Linezolid
Inhibits formation of ribosomes
Last resort treatment for Gram + bacteria,
VRE
**azole - Ketoconazole
Inhibitors of ergosterol synthesis
Anti-fungal
Amphotercin
Binds ergosterol so cell membrane leaks ions
Anti-fungal
Caspofungin
Inhibits glucan synthesis
Anti-fungal
What are three targets for anti-fungals?
- Ergosterol
- Glucan
- Chitin
What protozoa causes amebiasis (amoebic dysentery)
Entamoeba histolytica
What protozoa causes diarrhea and fever?
Giardia lamblia
Metronidazole (Flagyl)
Binds electron transport proteins, resulting in cell death
Only kills dividing cells, not cysts
Anti-protozoan, anti-biotic, anti-parasitic
Infections of GI, vagina, urethra
DO NOT TAKE WITH ALCOHOL –> vomiting
What parasite causes malaria? How is it propagated?
Plasmodium
Mosquito bites –> blood
Chloroquine
Binds heme
Anti-parasitic, malaria
Mebendazole
Inhibits microtubule formation and paralyzes worms
Anti-parasitic, helminthic worms
Does Mebendazole enter systemic circulation?
No - low toxicity
**mycin - Streptomycin, Azithromycin (Z-pack), Clindamycin, Erythromycin
Antibiotic - inhibits proteins synthesis
Clindamycin/Erythromycin - inhibit translocation
Azithromycin - community-acquired pneumonia, broad spectrum antibotic
Meropenem
Anti-biotic
Last resort treatment for Gram - bacteria
Artemisinin
Anti-parasitic
Drug resistant strains of malaria