Chemical ways to remove microorganisms

Radiation

Damages DNA

• thymidine/pyrimidine dimers

• ionizing radiation (x rays, gamma rays, electron beams)

• nonionizing radiation (UV)

Alcohol

Denatures proteins

Dissolves lipids

What is alcohol great for?

Degerming

What percentage does alcohol need to be diluted to to be effective?

• 95-60% is more effective at lower exposure times

Alcohol is best against

Effective against vegetative cells (Bacteria)

• not great for spores or viruses without envelopes

Phenol

Disrupts plasma membrane

Phenols

phenol chemically modified to be more effective

• Lysol

Bisphenols

disrupt plasma membranes

• hexachlorophene

• triclosan

Biguanides

Disrupt plasma membranes

Chlorhexidine

• used for surgical scrub/pre-op

Aldehydes

Inactivate proteins by crosslinking with functional groups (-NH2, -OH, -COOH, -SH)

• glutaraldehyde, formaldehyde

Peroxigens

Great at disinfecting inanimate objects

• oxidizing agents

• hydrogen peroxide

Why is peroxigen not a great antiseptic?

it gets easily broken down to oxygen and water by enzymes in our bodies (catalase)

Halogens

Disrupts protein configuration by oxidation

• bleach

• chlorine

• iodine - also disrupts plasma membrane

Heavy metals

Denature proteins

• Ag, Hg, Cu

Heavy metal oligodynamic action

- low concentrations still exert antimicrobial activity