The Effect of Disinfectants on Bacteria

The purpose of a disinfectant is to destroy, neutralize, or inhibit the growth of bacteria on surfaces other than skin. Different disinfectants achieve this result in different ways.

Alcohols

• Alcohols make the lipids that are part of the outer protective cell membrane of each bacterium cell more soluble in water so that the cell membrane loses structural integrity and falls apart. As the cell membrane disintegrates, alcohol can enter the cell, denature proteins within each bacterium and disrupt many of the cell's vital functions.

Formaldehyde

• Formaldehyde alkylates (adds an alkyl group to) the amino and sulfhydral groups of proteins and ring nitrogen atoms of purine bases, altering RNA, DNA and protein synthesis.

Glutaraldehyde

• Glutaraldehyde alkylates sulfhydryl, hydroxyl, carboxyl and amino groups and cause synthesis disruptions like those for formaldehyde.

Peroxides

• Peroxides (such as hydrogen peroxide and benzoyl peroxide) generate destructive hydroxyl free radicals that attack membrane lipids, DNA, and other essential cell components. A naturally occurring vaginal bacteria called Lactobacillus jensenii produces hydrogen peroxide and helps inhibit the transmission of urinary tract infections.

Phenol

• Phenol penetrates and disrupts the cell wall and precipitates the cell proteins. Bacterial death follows inactivation of essential enzyme systems and leakage of essential metabolites out from the cell wall.