Microbiology Student Outline – Chemotherapy and Antibiotics

Chemotherapy and Antibiotics

Reading: Chapter 20

1. Introduction

A. Selective Toxicity

2. Chemotherapy

A. Definitions:

i. Chemotherapeutic Agents

ii. Antibiotics

iii. Spectrum of Microbial Activity

a. Narrow-spectrum Antibiotics

• Penicillin G

b. Broad-spectrum Antibiotics

• Superinfection

* Elimination of competition: Candida albicans

* also, Resistance to Drugs

iv. Bactericidal

v. Bacteriostatic

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Microbiology Student Outline – Chemotherapy and Antibiotics

B. Characteristics of a good chemothereputic agent

i. Selective Toxicity

ii. non-allergenic

iii. disease should not become readily resistant to the drug

iv. host should not destroy, neutralize, or excrete the drug

v. the drug must be able to reach the infection site.

3. Overview of Chemotheraputic Modes of Action (Pull out downloadable handout)

4. Inhibition of Cell Wall Synthesis

A. Penicillin (pp. 559 - 562)

• Antibiotics

• History & Alexander Fleming

i. Structure

ii. Mechanism

• Peptidoglycan

* N-acetylgucosamine

* N-acetylmuramic acid

• Transpeptidase

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Microbiology Student Outline – Chemotherapy and Antibiotics

iii. Draw Backs

a. Anaphylactic Reaction

b. Penicillinase

c. Resistance

• Methicillin

• MRSA (Methicillin -resistant Staphylococcus aureus)

• b-Lactamase Inhibitors (Pull out handout)

iv. Extended Spectrum Penicillins

• Semisynthetic Penicillins

a. Ampicillin

b. Amoxicillin

B. Monobactams

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Microbiology Student Outline – Chemotherapy and Antibiotics

C. Cephalosporins (pp. 561 - 563)

i. General Information

ii. Generations (Partial list, there are now fourth generation cephalosporins):

a. First Generation: Second Generaion: Third Generation:• Cefadroxil • Cefaclor • Cefixime• Cefazolin • Cefamandole • Cefoperazone• Cephalexin • Cefmetazole • Cefotaxime• Cephalothin • Cefonicid • Cefpodoxime• Cephapirin • Ceforanide • Ceftazidime• Cephradine • Cefotetan • Ceftizoxime

• Cefoxitin • Ceftriaxome• Cefprozil• Cefuroxime• Loracarbef

ii. Mechanism

iii. Side Effects

D. Bacitracin (p. 563)

i. General Information

ii. Mechanism

iii. Side Effects

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Microbiology Student Outline – Chemotherapy and Antibiotics

E. Vancomycin (p. 563)

i. General Information

ii. Mechanism

iii. VRE (Vancomycin-resitant Enterococci)

5. Mycobacterial Antibiotics (p. 463)

A. Mycobacteria Cell walls

i. Mycolic Acids

B. Isoniazid (INH)

i. Mycobacterium tuberculosis

C. Ethambutol

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Microbiology Student Outline – Chemotherapy and Antibiotics

6. Inhibitors of Protein Synthesis

A. Chloramphenicol (pp. 563 - 565)

i. General Information

ii. Mechanism

iii. Side Effects

B. Aminoglycosides (p. 565)

i. General Information

• Amino Group ( - NH2 )

ii. Mechanism

iii. Administration

iv. Side Effects

• Neomycin

Relative ototoxicity:

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Microbiology Student Outline – Chemotherapy and Antibiotics

neomycin > streptomycin > kanamycin > amikacin, gentamicin, tobramycin, netilmicin

C. Tetracyclines (p. 565)

i. General Information

ii. Mechanism

iii. Side Effects

iv. Heart Attacks

D. Macrolides (Erythromycin) (p. 566)

i. General Information

ii. Mechanism

iii. Side Effects

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Microbiology Student Outline – Chemotherapy and Antibiotics

iv. Resistance

E. Streptogramins

F. Oxazolildinones

7. Disruption of the Plasma (Cell) Membrane (p. 566)

A. Polymyxins

i. General Information

ii. Mechanism

iii. Side Effects

8. Inhibition of Nucleic Acid Synthesis (p. 567)

A. Rifampin

i. General Information

ii. Mechanism

iii. Side Effects

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Microbiology Student Outline – Chemotherapy and Antibiotics

9. Competitive Inhibition (pp. 567 - 568)

A. Sulfonamides

i. How they work

• Synergism

ii. Methods of Resistance

NH2 NH2

COOH SO2NH2

PABA Sulfonilamide

B. Trimethoprim

PABABlocked by Sulfonamides

Dihydrofolic AcidBlocked by Trimethoprim (Dihydroloate Reductase)

Tetrahydrofolic Acid

• Bactrim

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Microbiology Student Outline – Chemotherapy and Antibiotics

10. Antifungal Drugs (pp. 567 - 569)

A. Griseofulvin (p. 569)

i. General Information

ii. Mechanism

iii. Side Effects

?? B. Nystatin

i. General Information

• Intestinal Candidiasis

ii. Mechanism

J. Lincomycin - and Clindamycin i. General Information ii. Mechanism iii. Side Effects

11. Antiviral Drugs (pp. 567 - 571)

A. Nuceoside and Nucleotide Analogs

i. Acyclovirii. Gamcicloviriii. Ganciclovir

B. Protease Inhibitors

C. Integrase Inhibitors

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Microbiology Student Outline – Chemotherapy and Antibiotics

D. Fusion Inhibitors

12. Antiprotozoan Durgs (p. 571)

A. Quinine

B. Metronidazole (Flagyl)

13. Antihelminthic Drugs (p. 571)

14. Drug Resistance (p. 572 - 573)

A. How Bacterial may become resistant

B. Determinative Assays

i. Kirby-Bauer Susceptibility Test

• Antibiotic Disks

• Zone of Inhibition

ii. Tube Dilution Method

a. Minimum Inhibitory Concentration (MIC)

B. Antibiotic Resistance and Abuse (p. 575)

i. Acquired Resistance

ii. Hospitals

iii. Livestock Feeds

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