2. Type of Microorganism
- Gram-negative bacteria are generally more
resistant than gram-positive bacteria to disinfectants and antiseptics.
- Pseudomonas and Burkholderia have porins in
the cell wall with characteristics that make them resistant to a
lot of chemicals and antibiotics. They can actually grow in some
disinfectants and antiseptics due to this resistance combined with
the ability to metabolize some unusual molecules.
- Mycobacteria, endospores, and protozoan cysts and
oocysts are very resistant to disinfectants and antiseptics.
- Nonenveloped viruses are generally more resistant
than enveloped viruses to disinfectants and antiseptics.
- Lipid envelope is a target for chemical injury
- Prions resist disinfection and autoclaving - an
hour soak in sodium hydroxide followed by an hour of autoclaving at
136º C is "fairly effective".
3. Physiological State
- Actively growing more susceptible.
- Endospores least susceptible.
- Organic material inhibits chemicals by binding them
and can insulate microorganisms against heat.