Antibiotics Flashcards
What is the structure of Gram (+) bacteria?
Thick peptidoglycan layer, contains teichoic acid, no outer membrane, stains purple.
What is the structure of Gram (-) bacteria?
Thin peptidoglycan layer, outer membrane with lipopolysaccharides (LPS), contains porins, stains pink.
What are the five general properties of antimicrobial agents?
Solubility in body fluids, selective toxicity, stability and resistance to degradation, spectrum of activity, limited side effects.
Name three Gram (+) bacteria and the diseases they cause.
Staphylococcus aureus: skin infections.
Streptococcus pyogenes: strep throat.
Clostridium difficile: pseudomembranous colitis.
Name three Gram (-) bacteria and the diseases they cause.
Escherichia coli: UTIs.
Pseudomonas aeruginosa: hospital-acquired infections.
Neisseria gonorrhoeae: gonorrhea.
Name three atypical bacteria and the diseases they cause.
Mycoplasma pneumoniae: atypical pneumonia.
Chlamydia trachomatis: STIs.
Rickettsia spp.: Rocky Mountain spotted fever.
What is the spectrum of activity of antibiotics?
The range of pathogens an antibiotic can target (narrow vs. broad-spectrum).
What is selective toxicity in antibiotics?
The ability to target bacterial processes without harming host cells.
What are the five main targets of antimicrobial agents?
Cell wall synthesis: penicillins, cephalosporins.
Cell membrane: polymyxins.
Protein synthesis: tetracyclines, macrolides.
Nucleic acid synthesis: fluoroquinolones.
Folic acid synthesis: sulfonamides, trimethoprim.
How do beta-lactam antibiotics kill bacteria?
Inhibit transpeptidase enzymes, preventing peptidoglycan cross-linking, leading to bacterial lysis.
What are three mechanisms of beta-lactam resistance?
Beta-lactamases hydrolyze the beta-lactam ring.
Altered penicillin-binding proteins (PBPs).
Decreased permeability via porin mutations in Gram (-) bacteria.
What are examples of penicillins and their uses?
Penicillin G: narrow-spectrum, Gram (+), used for strep, C-diff, meningitis.
What are examples of cephalosporins and their uses?
Cephalexin: first-generation, Gram (+), used for skin infections and UTIs.
What are examples of carbapenems and their uses?
Imipenem: broad-spectrum, used for serious hospital-acquired infections, sepsis, and pneumonia.
What are examples of monobactams and their uses?
Aztreonam: Gram (-), used for UTIs, lower respiratory tract infections, and Gram (-) sepsis.