chapter 27 : antimicrobial therapy

antibiotics

compounds produced by one species of microbe that can kill or inhibit the growth of other microbes

selective toxicity

selectively kill or inhibit the pathogen but not the host

which of the following would provide the best target for a new antibacterial antibiotic 

ribosomes 

broad spectrum 

drugs are effective against many species 

narrow spectrum

drugs are effective against a few, or even a single, species

bactericidal

antibiotics kill target organisms

bacteriostatic 

antibiotics prevent the growth of organisms 

minimal inhibitory concentration MIC

lowest concentration of the drug that prevents growth

targets for selectivley toxic antibiotics

cell wall synthesis, cell membrane integrity, DNA synthesis, RNA synthesis, protein synthesis, metabolism

transpeptidases 

what the peptide side chains are cross-linked by 

the precursors are polymerized to the existing cell wall structure by

transglycosylases

the precursors are attatched to a species membrane lipid called ___ on the cytoplasmic side of the cell membrane

bactoprenol

penicillin 

beta-lactam ring structure. bind and inhibit the transpeptidase enzyme that cros-links peptidoglycan chains 

beta-lactamase enzyme

that cleaves the critical beta-;actam ring of beta-lactam antibiotics

carbapenems

extended-spectrum penicillins not affacteed by most beta-lactamase enzymes

antibiotics that target others steps in peptidoglycan synthesis

vancomycin, cycloserine, bacitrain (VCB)

What drugs poke holes in the cell membrane

gramicidin, polymyxin, and daptomycin (GDP)

who discovered penicillin and when

alexander flemming in 1928 and later purified by florey and chain 

How do beta-lactams (penicillin, cephalosporins, carbapenems) work

Bind transpeptidases → prevent peptidoglycan cross-linking.

Name antibiotics that inhibit DNA synthesis.

Sulfa drugs, Quinolones (ciprofloxacin), Metronidazole

Name RNA synthesis inhibitors

Rifampin, Actinomycin D.

30S ribosome inhibitors?

Aminoglycosides (streptomycin, gentamicin), Tetracyclines

What are the 3 main antibiotic resistance strategies

Keep drug out (destroy, decrease permeability, efflux pumps).
2. Prevent binding (mutations, modifying enzymes).
3. Dislodge bound antibiotic (ribosome protection

What are ESKAPE pathogens

Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter sp

What are persister cells

Dormant subpopulations tolerant to antibiotics, often found in biofilms

How is resistance acquired?

De novo mutations or horizontal gene transfer (conjugation, transformation, transduction

who purified penicillin

Howard Florey and Ernst Chain