Microbio Exam 3 chapter 11

What is the specific terminology of microbial controls?

Sterilization

Disinfection

Antisepsis

Degerming

Sanitization

What is Sterilization?

Removes all microbial life (including endospores & viruses)

What is disinfection?

Removes pathogens on objects (non-living)

What happens in antisepsis?

Removes pathogens on living tissue

What is degerming?

Mechanical removal (example: Alcohol swab before injection) 

What is sanitization?

Reduces microbes to safe public levels 

What is Sterilization?

Everything dead (most extreme)

What is Disinfection?

Kills most pathogens (not all)  

What is different antisepsis then disinfection?

Like disinfection but safe for skin 

Identify the types/parts (not specific organisms) of microorganisms that are most resistant and least resistant to control measures. 

• Prions  

• Endospores  

• Protozoan cysts  

• Parasites  

• Gram-negative bacteria  

• Gram-positive bacteria  

• Fungi  

• Viruses  

• Vegetative bacterial cells

Define -cidal

Kills microbes  

What is an example of cidal?

bactericidal, fungicidal  

What is the action of -cidal?

microbes stay dead 

Define -static

Inhibits growth (temporary)  

What is an example of -static?

Bacteriostatic 

What is the action of -static?

microbes grow again  

What are the mode of action for physical and chemical agents?

• Damaging cell membranes  

• Damaging proteins  

• Damaging DNA/nucleic acids  

What is an example of moist heat?

Autoclave

What is the MOA of moist heat?

• Denatures proteins  

• Destroys cell membranes and cell walls  

What are the results of moist heat?

Sterilization (kills endospores)  

What is the example of dry heat?

incineration, dry oven 

What is the MOA of dry heat?

• Denatures proteins  

• Destroys cell membranes and cell walls 

What is the results from dry heat?

Complete destruction of microbes  

What is the example of cold temperatures?

Refrigeration, freezing  

What is the MOA of cold temperatures?

Slow metabolism and microbial growth 

What is the result of cold temperature?

preservation (not killing)   

What is an example of desiccation?

Drying

What is the MOA of desiccation?

Removes water = inhibits metabolism  

What is an example of lyophilization?

Freeze-drying

What is the MOA of lyophilization?

Combines freezing + desiccation  

What is the results of lyophilization?

Preserves microbes  

What is an example of ionizing radiation?

Gamma rays, X-rays

What is the MOA of ionizing radiation?

Break DNA strands  

What are the results of ionizing radiation?

Sterilization (deep penetration)  

What is an example of Non-ionizing Radiation?

UV light 

What is the MOA of Non-ionizing Radiation?

Damages DNA (thymine dimers)  

What is the result of Non-ionizing Radiation?

Disinfection of surfaces (low penetration)   

What is an example of filtration?

• HEPA: >0.3um  

• Membrane: >0.22um  

What is the MOA of filtration?

Physically removes microbes 

Define what thermal death point (TDP) is

Lowest temp to kill all microbes in 10 min  

Define what thermal death time (TDT) is

Time required to kill all microbes  

Define what decimal reduction time (DRT) is

Time to kill 90%

What are the desirable characteristics of a chemical control agent?

• Fast acting  

• Effective at low concentration  

• Broad spectrum  

• Low toxicity  

• Stable  

• Penetrating  

• Noncorrosive  

• Affordable 

What is an example for Phenolics?

• Lysol  

• Pine-Sol 

What is the MOA for Phenolics?

• Denature Proteins  

• Destroy cell membrane  

• Damage cell walls 

What is an example of Bisphenols?

Hexachlorophene 

What is the MOA of Bisphenols?

Disrupt plasma membrane  

What is an example of Biguanides?

Chlorhexidine 

What is the MOA for Biguanides? 

Disrupt plasma membrane 

Notes: Commonly used on skin and mucous membranes

What is an example of halogens?

• Chlorine = Hypochlorite (bleach)  

• Iodine = Iodophores (Betadine)  

What is the MOA for halogens?

Denature proteins  

What is an example for alcohols?

• Ethanol  

• Isopropanol  

What is the MOA for alcohols?

• Denature proteins  

• Dissolve lipids (membrane damage)  

What must be require for alcohol to be effective?

Water

What is an example of Hydrogen peroxide (Oxidizing agents)?

• 3% hydrogen peroxide  

• 35% hydrogen peroxide

What is the MOA of Hydrogen peroxide (Oxidizing agents)?

• Produce free radicals = damage proteins and  DNA  

• Release oxygen (O2), which helps kill microbes  

What is an example for heavy metals?

• Silver (Ag)  

• Mercury (Hg) 

• Copper (Cu)

What is the MOA for heavy metals?

Denature proteins  

What is an example of Detergents & soaps?

Benzalkonium chloride (a quaternary ammonium compound)

What is the MOA for Detergents & soaps?

• Disrupt plasma membranes  

• Interfere with proteins  

What is an example of aldehydes?

• Glutaraldehyde  

• Formaldehyde 

What is the MOA of Aldehydes?

• Denature proteins  

• Damage DNA 

What is an example of gases?

Ethylene oxide  

What is the MOA for gases?

• Denature proteins  

• Disrupt DNA  

Define denaturing proteins

proteins lose structure and function  

Define dissolving lipids

Disrupt the cell membrane  

What are the limitations of alcohols?

• Require water to be effective (best at ~70%, not 100%) 

• Not sporicidal = do NOT kill endospores  

• Limited effectiveness against some non-enveloped viruses  

• Evaporate quickly = short contact time  

• Reduced effectiveness in presence of organic matter (dirt, blood)  

Which test are used for chemical effectiveness?

1. Use-dilution test

2. Minimum inhibitory concentration (MIC)

3. Disk diffusion (Kirby-Bauer)

What does the Use-dilution test, test for?

tests killing (disinfection) 

What does the Minimum inhibitory concentration (MIC) test for?

Test inhibition, not killing  

What does the disk diffusion (kirby-bauer) test for?

Tests effectiveness visually  

What is the most resistance?

prions and endospores

What is the least resistance?

Enveloped virus