Microbiology Chapter 5

Front 1

Describe detergents

Back 1

amphipathic compounds with two parts

- A non-polar (a long hydrocarbon chain) that attaches to grease
- A polar part that is attracted to water

Front 2

Describe detergent types

Back 2

Anionic detergents = The active part has a negative charge

- Include soaps
- Are effective cleansers, but have little antibacterial effects

2. Cationic detergents = The active part has a positive charge

- Example: Quaternary Ammonium Compounds
- Benzalkonium chloride, Zephiran

- Have great antibacterial effects in the absence of contaminating organic matter
- Used as antiseptics, and disinfectants
- Act by disrupting membranes mainly

Front 3

Describe Phenol

Back 3

Act by disrupting membranes and denaturing proteins

• Phenol was the first widely used antiseptic and disinfectant
- The father of antiseptic surgery was Joseph Lister
- Its use is now limited because of its odor and skin irritation

Front 4

Describe Phenolics

Back 4

Act by disrupting membranes and denaturing proteins
Cresols - active ingredient in Lysol
Halogenated phenols - work even in presence of organic contaminating matter
Triclosan-broad spectrum antibacterial/antifungal agent. Blocks lipid synthesis

Front 5

Describe Alcohols

Back 5

dissolve membrane lipids and denatures proteins

Front 6

Describe halogens

Back 6

act as oxidizing agents; may denature protein
5: Fluorine, Bromine, Chlorine, Iodine, Astatine

Front 7

Describe alkylating agents

Back 7

alkylating proteins and NA's
Formaldehyde.37% solution=formalin
-used for germicide, inactivate viruses for vaccines

Gluteraldehyde. 2% solution=CIDEX
-liquid sterilient

Ethylene oxide - highly penetrating gaseous sterilant

Front 8

Describe Heavy Metals

Back 8

denature proteins. extremely small amounts can be lethal (oligodynamic action)

organic mercuric compounds - mercurochrome

silver nitrate - drops used for baby's eyes to fight Neisseria gonorrhoeae

Copper Sulfate - to control algal growth

Front 9

Describe Organic Acids

Back 9

low pH denatures proteins
Propionic acid = antimicrobial in bread, cheese
Lactic acid = antimicrobial in yogurt, pickled foods
Benzoic acid = Antimicrobial in margarine, relishes
Acetic acid = vinegar

Front 10

Antibiotic producers are divided into these groups:

Back 10

Actinomycetes - Streptomyces
Molds - Penicillium
Bacteria other than Actinomycetes- Bacillus

Front 11

This antibiotic can affect Gram + and Gram -

Back 11

tetracycline

Front 12

This is used against Mycobacterium tuberculosis

Back 12

isoniazid

Front 13

Describe penicillins

Back 13

- beta-lactam antibiotics
- Inhibit the transpeptidation reaction
- Natural penicillins
- Include Penicillin G
- Effective mainly against Gram-positive bacteria

Front 14

Describe semisynthetic penicillins

Back 14

Effective against Gram-negative bacteria
- Example: Ampicillin

- Resistant to penicillinases
- Example: Methicillin
- Unfortunately, MRSA strains have appeared!

Front 15

Describe cephalosporins

Back 15

beta-lactam antibiotics

- Inhibit the transpeptidation reaction

- Divided into four “generations” depending on their effectiveness against Gram-negative bacteria

- The later generations are generally more effective against Gram-negative bacteria and less susceptible to destruction by beta-lactamases

Front 16

Describe Vancomycin

Back 16

Vancomycin
- NOT BETA-lactam antibiotics
- Inhibits transport of the cell wall precursors by the carrier
- Effective against enterococci, but alas VRE strains have evolved!
- The only drug that is effective against MRSA

BUT NOW THERE IS VRSA

Front 17

Describe polymyxins

Back 17

have a cationic detergent mode of action

generally more effective against Gram -

Front 18

Describe streptomycin

Back 18

inhibits protein synthesis at the 30S subunit

Front 19

Describe tetracycline

Back 19

inhibits protein synthesis at the 30S subunit

Front 20

Describe erythromycin

Back 20

inhibits protein synthesis at the 50S subunit

Front 21

Describe chloramphenicol

Back 21

inhibits protein synthesis at the 50S subunit

Front 22

This is the steps for the future of drug discovery:

Back 22

1) genomics - use genome data to ID new targets
2) rational drug design - design drugs to interact at the active site of an enzyme
3) nanotubes - use of small cyclic peptides that form tubes within membranes
4) combinatorial chemistry - create and test random variations of a molecule

Front 23

Describe the anti-fungal antibiotics

Back 23

Inhibition of cell membrane synthesis:
Azoles
Terbinafine
Tolnaftate

Disruption of cell membrane:
Amphotericin B
Nystatin

Inhibition of NA synthesis:
5-fluorocytosine

Inhibition of microtubule assembly:
Griseofulvin

Inhibition of cell wall synthesis:
Caspofungin