Download Ex. 20 Antibiotic Disk Sensitivity

Antibiotics
 Naturally occurring compounds produced by bacteria
and or fungi, that kill or inhibit other microbes
 Many Antibiotics are produced by
 2 Genera of Bacteria
 Streptomyces
 Bacillus
 1 Fungal Genus
 Penicillium
Common Antibiotics
 Stretomycin –
Streptomyces
 Protein synthesis
 70S Ribosme
 Bacitracin -
Bacillus
 Cell Wall synthesis
 Penicillin -
Penicillium
 Cell Wall synthesis
Selective toxicity
 The antibiotic must harm the pathogen without
harming the host cell
 Antibiotics do this by:
 1. Attacking the 70S Ribosome (Protein synthesis)
 2. Attacking the Cell Wall
Kirby-Bauer Antibiotic Disk
Sensitivity Test
Kirby-Bauer Antibiotic Disk
Sensitivity Test
MIC
 Minimum Inhibitory Concentration
 Least amount of an antibiotic that will inhibit the
growth of a microbe
 MRSA
 Methicillin Resistant Staphylococcus aureus
 Vancomycin
 Last line of defense against MRSA – which has led to
 VRE
 Vancomycin Resistant Enterococci