1. Chapter 20-Antimicrobial Agents
_______________:The use of drugs to treat a disease (not necessarily infectious)
Antimicrobial drugs: Interfere with the growth of microbes within a
host
Antibiotic: Substance produced by a microbe that, in small amounts, ____________ another microbe
Selective toxicity: A drug that kills harmful microbes without damaging the host

2. DISCOVERY and PURIFICATION of PENICILLIN
1928 – ___________ discovered penicillin, produced by Penicillium.
1940 – Howard Florey and Ernst Chain performed first clinical trials of penicillin.
Naturally occurring antimicrobials
Metabolic products of bacteria and fungi
_________: Streptomyces sp., Bacillus sp.
_________: Penicillium sp., Cephalosporium sp.
Figure 20.1

3. The Action of Antimicrobial Drugs
Broad-spectrum
Affect wide range of G+ and G- bacteria
Disadvantage is disruption of ___________
Ex. Tetracycline
Narrow-spectrum
Affect small, __________ range of bacteria
Gram positive only or gram negative only
Ex. Penicillin G affects G+ but not G- bacteria

4. TYPES OF ANTIMICROBIAL ACTION
Drugs may kill or inhibit bacterial growth
1._________________________ the growth of
microorganisms
Bacteriostatic drugs rely on host immunity to
eliminate pathogen
2._________________________ microorganisms
Bacteriocidal drugs are
useful in situations when
host defenses
cannot be relied upon to
control pathogen

5. Adverse Effects of Antimicrobial Drugs
____________ REACTIONS
Allergies to penicillin
Allergies often life threatening
TOXIC EFFECTS
Ex.: Aplastic anemia
Body cannot make RBC or WBC
SUPPRESSION of _______________
Antibiotic associated colitis
Toxic organisms given opportunity to establish themselves
ANTIMICROBIAL ________________
Microorganisms have innate or adaptive resistance to antibiotics

6. Major Action Modes of Anti_______________ Drugs

7. ANTI_____________ ANTIBIOTICS
MODE of ACTION: Interference with essential processes of Mycobacterium tuberculosis
1. _________ (NIH) – inhibits synthesis of _______ acid
2. Ethambutol – inhibits incorporation of mycolic acid into
the cell wall
MODE of ACTION: Blocks _______________
1. Rifampin

8. Anti-___________ Drugs
amantadine and rimantadine
Mode of action: block the ______________ of
influenza virus after it
enters cell
Reduces severity and duration of disease
Zidovudine ____ and _____________
Mode of action: blocks nucleic acid synthesis

9. ANTI_______________ DRUGS
Mode of action:
Inhibition of ergosterol synthesis
Amphotericin B
Produced by Streptomyces species
Treatment of ____________ fungal diseases
Toxic to kidneys
___________________
Treatment of athlete’s foot and vaginal yeast infections
Ketoconazole
Less toxic than miconazole
Topical application for cutaneous mycoses
Figure 20.15

10. Anti-____________ Drugs
Chloroquine
Inhibits DNA synthesis
Plasmodium species - __________
Metronidazole
Damages DNA
___________ sp., Trichomonas sp.

11. Anti-________________ Drugs
Niclosamide
Prevents ATP generation
_______________
Praziquantel
Alters _________ permeability
Flatworms
Mebendazole
Interferes with ________________________
Effective against tapeworms and roundworms
Used in livestock industry

12. KIRBY BAUER ANTIMICROBIAL SUSCEPTIBILITY TESTING:
Figure 20.17

13. FOUR MAIN MECHANISMS of ANTIBIOTIC __________________________
Resistance genes are often on plasmids or transposons that can be transferred between bacteria.

14. Antibiotic ______________
Misuse of antibiotics selects for resistance
Misuse includes:
Using ___________________ antibiotics
Using antibiotics for the common cold and other _________________ conditions
Use of antibiotics in ________________
Failure to complete the prescribed regimen
Using someone else's leftover prescription

15. Antimicrobial Resistance
Staphylococcus aureus
Common cause of __________________ infections
Becoming increasingly resistant
In past 50 years most strains acquired resistance to penicillin
Due to acquisition of ____________ genes
Until recently most infections could be treated with methicillin (penicillinase resistant penicillin)
Many strains have become resistant
MRSA  methicillin resistant
MRSA strains are becoming resistant to vancomycin