Essay 2- Antiseptics. Historic data, antiseptic agents

subheadings for this essay

What is antisepsis?

killing of microorganisms with chemical methods

Antiseptic: substance that slows down growth of microorganisms

• Commonly used in hospitals

• prevents surgical and procedural infections

What is asepsis?

Killing or preventing the growth of microorganisms on body surfaces using physical methods

• Serves as a prophylactic measure against infection

e.g. hand hygiene, sterile equioment, proper wound dressing

What is disinfection?

• Microbial eradication using chemical substances

• not all forms of microbes

• won’t destroy spores

• used in hospital surfaces, instruments, and non-living materials

• alcohol, hydrogen peroxide

What is sterilization?

Microbial eradication using physical methods

• entirely free of microbes

• autoclave, dry heat, UV

History

• Pre-antiseptic period: up to 80% of surgical patients died from infection after surgery

• Joseph Lister (1867):

  • Introduced chemical prophylaxis for wound infection

    • used phenol to disinfect wounds and dressings

  • Used dressings,

  • Reduced lethality from infections

• Early methods:

  • No disinfection of instruments, rooms, or hands

  • Wounds washed with boiled rainwater, wine, boiling oil, or alcohol

  • Use of drums/containers for sterilizing items

Lister’s Method & Drawbacks

• Wound dressing: 5% carbolic acid (phenol) solution was applied to disinfect the wounds.

• Disinfection: 2-3% solution for hands, surgical instruments, and the surgical field

• Air spraying: 2.5% solution of phenol

  • Reduce airborne pathogens

• Drawbacks:

  • Toxicity, poisoning when inhaled

  • Skin rashes, eczema

    • prolnged contact causes skin irritation

  • Tissue necrosis

    • over use = tissue damage

types of antisepsis

1. physical

2. mechanical

3. chemical

4. biological

5. mixed

6. superficial and deep

   • on body surface or injected in tissues

7. local and general

physical antisepsis

Physical

• Creating unfavourable conditions for the growth of bacteria

• UV- damage pathogen DNA

• drainage tubes

  • remove bodily fluids, a breeding ground for pathogens

• open air

  • exposing wounds to the air

  • dry them out

  • less hospitable environment for bacteria

  • Also O2 promotes healing

Mechanical Antisepsis:

Primary surgical wound treatment

• irrigation

• flushing out foreign bodies

• removing necrosis or hematomas

• ensures the wound heals cleanly, quickly and reduce the risk of infection.

Chemical Antisepsis:

Uses chemical agents to destroy or inhibit the growth of microorganisms.

Local or general action

local- applied to the wound

• alcohol

• iodine based solutions

General - absorbed in the blood stream

• oral or injectable antibiotics

Biological:

Use of serum, vaccines, antibiotics, antitoxins, immunoglobulins

help fight infections by stimulating the body’s natural defenses or directly combating microorganisms.

Mixed:

act on the actual infection and target the pathogens,

• stimulate the body’s immune response to fight the infection.

combination of action both on the bacterial cell and the macroorganism.

What are antiseptics?

• chemical substances

• applied to living tissue/skin

• to reduce the possibility of infection

Types of Antiseptics (by Mode of Action)

• Bactericidal: Kill microorganisms

• Bacteriostatic: Inhibit growth and metabolism

Complications of Antisepsis

• Intoxication

• Lesions

• Allergic reactions

• Dysbacteriosis (imbalance of normal flora)

Requirements for a Good Antiseptic

• Bactericidal or bacteriostatic

• Non-toxic to cells/tissues/organs

• Effective on live tissue

• Stable over time

• Affordable

• Doesn’t inhibit local defense

• Easy to store

Structures of Antiseptics

Inhibit bacterial folic acid synthesis

Halogens: iodine, iodine-alcohol, hibitane, chloramines

• release free halogens (strong oxidisers)

• destroy microbial proteins and enzymes

Oxygenators: hydrogen peroxide, potassium permanganate (KMnO₄), boric acid

• disrupts microbial cell walls

• oxidises their proteins

Organic compounds: alcohol, formalin, lysol

• Disrupt microbial cell membranes and proteins

Heavy metals: sublimate (mercury), silver nitrate

• interfere with enzyme activity

Dyes: methylene blue, rivanol, tripaflavine

• disrupting microbial metabolism or growth.

Sulfonamides

• Inhibit bacterial folic acid synthesis

Antibiotics

• Depending on the class, many ways of destroying it.

• (e.g., inhibition of cell wall synthesis, protein synthesis, DNA replication, etc.)