Study Guide On Agents For Microbial Control

Name three categories of chemicals which are used as antimicrobials.

- Alcohols (70%... not 100%) - Oxidizing Agents (peroxide; ozone) -Gases (ethylene oxide)

Explain the difference between cleaning, disinfecting, sanitizing, and sterilizing. List two treatments that fall under each of these categories.

- Cleaning: "decontamination" reduction of pathogenic organisms to a level at which items are safe to handle w/o protective attire. (e.g. scrubbing with soap, important step to precede disinfection/sterilization) -Disinfecting/sanitizing: kills most targeted pathogens except spores (e.g. UV and pasteurization) -Sterilizing: kills spores & endospores, which are the hardest to penetrate (e.g. autoclaving & ionizing radiation)

Why might you choose a microbicidal treatment over a microbiostatic treatment or vice versa?

-A microbicidal treatment kills microbes, while microbiostatic inhibit the growth & the metabolism of a microbe. -You'd want to choose a microbiostatic treatment so that the slow growth of microbes will encourage the immune system to make antibodies rather than increasing the toxicity to cells & other organisms when treated w/ a microbial treatment.

Besides electromagnetic, chemical and high temperature treatments, name two other methods for inhibiting microbes.

1. drying/freezing 2. osmotic pressure

What should you consider when choosing an antimicrobial method?....when choosing a chemotherapeutic?

1. site 2. environmental conditions 3. time and concentration needed 4. susceptibility 5. Antibiotic considerations (administration, localization, clearance, expense, toxicity)

What are four things that may influence the effectiveness of an antimicrobial method?

1. susceptibility of microbes 2. pH 3. Temperature 4. time and concentration needed

Sporicides

Agents that kill bacterial and mold spores, can also be used during the process of terminal disinfection of embalming instruments and equipment.

Sanitize

To reduce the number of microbes to a safe level

Non Ionizing radiation

UV light, infrared, microwave, and radio waves (longer wavelength)

Bactericides (Disinfectants)

substances that kill bacteria

What strategies in the use of antimicrobials might reduce the chance of developing resistance?

treat them with three different antimicrobials at the same time to reduce the chance of developing resistance (e.g. hibiclens (mix of chlorine, phenolic, alcohol, and a little bit of detergent))

Virucides

Chemical agent have the capacity to or tending to destroy or inactivate viruses

Fungicides

Chemical agents capable of destroying, and/or inhibiting the growth of saprophytic or pathogenic fungi, including molds.

In general, what are the two mechanisms by which a chemical might inhibit growth of microbes.

Denature proteins and disrupt membranes

What characteristics of pathogens make them more or less resistant to disinfection?

Different groups of bacteria vary in their susceptibility: most resistant - prions - - most susceptible - enveloped viruses

Bacteriostatic

Inhibits bacterial growth

Autoclave

Piece of equipment used to sterilize articles by way of steam under pressure and/or dry heat

What is the difference between gamma rays, x-rays, UV light, visible light, and microwave as antimicrobial agents?

Gamma rays and x-rays are both ionizing radiations that can sterilize, as well as UV light (non-ionizing) which all cause damage to DNA molecules.

Why are gamma rays used to sterilize bandages and foods, rather than UV light?

Gamma rays are used to penetrate solids like bandages and foods, whereas UV light must come in direct contact to sterilize.

What is the difference between Pasteurization, autoclaving, and UHT treatments?

Pasteurization - rapid form sanitization (70*c for 20 sec) Autoclaving - sterilization in a pressure cooker like instrument (20 min) UHT - sterilization at ultra high temps (2 sec)

Ionizing radiation

gamma rays and x-rays (shorter wavelength)

Pasteurize

a process in which packaged and non-packaged foods are treated with mild heat, usually to less than 100 °C, to eliminate pathogens and extend shelf life