Antibiotics Flashcards
What are examples of organisms that produce antibiotics?
bacteria: streptomyces, bacillus
moulds: penicillium, cephalosporium
What are the two different types of antibiotics?
bacteriostatic - prevents it from growing further
bacteriocidal - kills it altogether
How do antibiotics work?
They target cellular targets - cell walls, cell membranes, nucleic acid, protein synthesis
What are examples of antibiotics?
penicillins, cephalosporins
tetracyclines, streptomycin
trimethoprim
Which antibiotics inhibit cell wall synthesis? How do these work?
penicillins, cephalosporins
bind to ‘penicillin binding proteins’ -> inhibit cross linking of cell wall -> accumulation of precursor cell wall units -> cell lysis
Which antibiotics inhibit protein synthesis? How do these work?
erythromycin - ribosome is prevented from translocating
tetracyclines - tRNA is blocked, no protein synthesised
streptomycin
Which antibiotics inhibit synthesis of essential metabolites?
trimethoprim
Which antibiotic causes injury to plasma membrane?
polymyxin B
Which antibiotics inhibit nucleic acid replication and transcription? How do these work?
quinolones - inhibit DNA gyrase -> prevents supercoiling of bacterial chromosome -> prevents ‘packing’ of DNA into bacterial cell
What are antibiotics?
naturally occurring antimicrobials - metabolic products of bacteria and fungi, reduce competition for nutrients and space
definition = a chemical substance produced by one organism that is destructive to another
How is antibiotic resistance developed? What are the causes of this?
Misuse of antibiotic selects for resistance mutants
Causes: using outdated/weakened antibiotics,
using antibiotics for common cold or other inappropriate conditions,
using antibiotics in animal feed
failing to complete the prescribed regimen
using someone else’s leftover prescription
What are some resistance mechanisms to antibiotics?
blocking entry
inactivating enzymes
alteration of target molecule
efflux of antibiotic
