Chapter 15: Antimicrobial Drugs • Chemotherapy The use of drugs to treat a disease • Antimicrobial drugs Interfere with the growth of microbes within a host • Antibiotic Inhibits “bacterial” growth; usually produced by bacteria or fungi • Selective toxicity Kills harmful microbes without damaging the host
22
Embed
Chapter 15: Antimicrobial Drugs ChemotherapyThe use of drugs to treat a disease Antimicrobial drugsInterfere with the growth of microbes within a host.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Chapter 15: Antimicrobial Drugs• Chemotherapy The use of drugs to treat a
disease
• Antimicrobial drugs Interfere with the growth of microbes within a host
• Antibiotic Inhibits “bacterial” growth; usually produced by bacteria or fungi
• Selective toxicity Kills harmful microbes without damaging the host
• Broad-spectrum antibiotic
• Superinfection
• Bactericidal antibiotic
• Bacteriostatic antibiotic
• 1928 – Fleming discovered penicillin;produced by Penicillium (a fungus).
• 1940 – First clinical trials of penicillin.
Figure 20.1
The First Antibiotic
Table 20.2
Antimicrobials and Modes of Action• Prevents cell wall synthesis
• Prevents protein synthesis
• Plasma membrane attack
• Prevents nucleic acid synthesis
• Disrupts biochemical pathways
• Penicillin
• Natural penicillins
• Narrow spectrum
• Use for Staphylococci, Streptococci, Spirochetes
• Vulnerable to penicillinases (beta lactamases)
Antibacterial Antibiotics: Inhibitors of Cell Wall Synthesis
Figure 20.8
Some bacteria can disrupt the functioning of penicillin
Penicillins
Figure 20.6
• Semisynthetic penicillins
• Penicillinase-resistant penicillins
• First was methicillin
• Extended-spectrum penicillins
• Effective against many Gram negatives
• Some effective against Pseudomonas aeruginosa
• Penicillins + -lactamase inhibitors
• Cephalosporins:
• more effective against gram-negatives than natural penicillins
Figure 20.9
Vancomycin:• Used against antibiotic resistant S. aureus (i.e. MRSA)
• VRE have emerged
Antiviral DrugsNucleoside and Nucleotide Analogs
Figure 20.16a
Antiviral DrugsNucleoside and Nucleotide Analogs
Figure 20.16b, c
• Protease inhibitors
• Entry and Uncoating inhibitors
• Viral release inhibitors
• i.e. Tamiflu
• Interferons, prevent spread of viruses to new cells
• Common treatment for Hepatitis C infection
Antiviral Drugs
Kirby-Bauer (Disk-Diffusion) Test• Antibiotic soaked disks are placed on cultured plate
• Zone of inhibition is measured and compared to table with known results
E test• Antibiotic gradient strip is placed on cultured plate
• Minimal inhibitory concentration (MIC) is determined
E Test
Figure 20.18
Broth Dilution Test• Can distinguish between MIC and MBC (minimal