The Control of Microbial Growth

 

 

Microbial Characteristics And Microbial Control

 

1. Temperature

 

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.

4. Environment

  • Organic material inhibits chemicals by binding them and can insulate microorganisms against heat.