Chalter 9: Chemical Control of Microbes (Phenol and the rest of it)

What is the 4 point scheme for chemical methods of control?

1. Does it achieve sterilization

2. Use/forms

3. Mode of action

4. Special characteristics

What is the 4 point scheme of phenol?

1. Does it achieve sterilization: Does not kill endospores; effective against bacteria, viruses, fungi

2. Use/forms: Phenol: used only in certain limited cases, such as in drains,

   cesspools, and animal quarter

3. Mode of action

4. Special characteristics: Toxicity of many phenolics makes them dangerous to use as antiseptics; many phenols banned in consumer products in 2017, including triclosan

What is the 4 point scheme of chlorhexidine?

1. Does it achieve sterilization: Does not kill endospores (doesn’t sterilize); effective against bacteria, viruses, fungi; effective antiseptic

2. Use/forms: Chlorhexidine: mild, low toxicity, rapid action as an antiseptic. used in hand scrubs, prepping skin for surgery, as an obstetric antiseptic, as a mucous membrane irrigant

3. Mode of action

4. Special characteristics: Effect can be variable

What is the 4 point scheme of Alcohol?

1. Does it achieve sterilization: Does not kill endospores (doesn’t sterilize); effective against bacteria, viruses, fung

2. Use/forms: 2a. Ethyl alcohol or Ethanol

   2b. Isopropyl alcohol or isopropanol

   Routinely used as skin degerming agents (70% to 95% solutions). Up to 50% dilution is effective.

3. Mode of action

4. Special characteristics: Rate of evaporation decreases effectiveness

What is routinely used in skin degerming? What are two examples of it? Is a higher concentration of alcohol better or worse?

Alcohol

Different forms:

1) Ethyl alcohol or Ethanol

2) Isopropyl alcohol or isopropanol

Routinely used as skin degerming agents (70% to 95% solutions). Upto 50% dilution is effective. (can be an antiseptic)

• Lower concentration is better because alcohol requires water to be effective and denature things

What is the 4 point scheme of detergents?

1. Does it achieve sterilization: Cannot kill endospores. Effective against viruses, algae, fungi and Gm+ bacteria, low level of disinfection (are disinfectants)

2. Use/forms: Cationic detergents, such as quaternary ammonium compounds (“quats”): used to clean restaurant utensils, dairy equipment, equipment surfaces, restrooms

3. Mode of action

4. Special characteristics: Activity is greatly reduced in presence of organic matter

What is the 4 point scheme of heavy metal compounds?

1. Does it achieve sterilization: Cannot kill endospores. Effective against viruses, fungi and some bacteria (good antiseptics and preservatives)

2. Use/forms: 2a. Organic mercury tinctures are effective antiseptics; organic mercurials serve as preservatives in cosmetics, ophthalmic solutions

3. 2b. Silver nitrate solutions are used for topical germicides and ointments (used in nerborn baby eyes to prevent infection)

4. Mode of action

5. Special characteristics: Microbes can develop resistance, Toxicity and Allergic reactions

What is the final agent that we talked about in the lecture for chemical Control methods? What is the target microbes, forms, indicator for use, and limitations?

Acids and Alkalis

• Target: Some bacteria, fungi, viruses

• Forms: Organic acids in food production

• Use: Food, manufacturer, deodorant, deodorizer

• Limitations: Large changes in pH can be corrosive

Top hat Q: The use of iodine compounds to prepare the skin for surgery is known as

Antisepsis

Which of the following chemicals are considered sterilizing agents?

Chlorhexidine, hydrogen peroxide, alcohol, acetic acid, or none of these choices is correct

It isn’t an energy stresses is correct because it does not provide the specific concentration of hydrogen peroxide