x Micro, 4, Control of Microorganisms Flashcards
Bactericide
KILL all bacteria, nothing else
Germicide - kill germs
Virucides - kill virus
Bacteriostatic
- inhibit bacteria growth
- stops reproduction of bac.
- controls growth
- may not kill
Sterilization
- Eliminate ALL microorganisms
- KILL bac, vir, fung, spores
Methods of Sterilization
Heat, Chem, Radiation, Pressure, Filtration
Asepsis
free of all forms of microorganisms
Disinfection
destroying microorganisms on non living objects
Antisepsis
antimicrobial substance applied to living tissue/skin to reduce possibility of infection, sepsis or putrefaction.
Sanitation
promoting hygiene to prevent human contact with waster.
Antibiosis
biological interaction btwn 2 or more orgs that is detrimental to at least one
Drying
remove water cells, shrivel, die
foods can be dried by mixing them with salt or sugar.
Lyophilization
liquids are quick frozen, then subject to evacuation, which dries material (salted meats, sugared fruit)
TDP (Thermal Death Point)
lowest temp when microorgs killed in 10 min.
TDT (Thermal Death Time)
minimum amount of time to kill all microorgs at given temp.
DRT (Decimal Reduction Time)
amount of time to destroy 90% of microbial population.
Types of HEAT control methods
- DRY HEAT: kill by oxidizing proteins
- DENATURATION: 3D protein to 2D, breakdown
- MOIST HEAT: kill in boiling water, most killed in 2-3 min.
- AUTOCLAVE: high press, steam is superheated for sterilization
Types of PHYS control methods
- Pasteurization
- Radiation
- Filtration
Pasteurization
- lower bacterial count in milk, dairy
- does NOT sterilize
- kills orgs that cause listeriosis, tuberculosis, burcellosis, typhoid fever, diptheria
- DENATURES PROTEIN
Radiation
- damages DNA
- Ionizing radiation (xrays, gamma, electron beams)
- nonionizing radiation (UV)
- microwaves kill by heat, not very microbial
Filtration
- liquid passed thru screen filter our microorgs
- vacuum can be used to pull fluids through filter
- Osmotic Press leads to plasmolysis, cause loss of water from cell, contracting plasma membrane
CHEM methods of control
- not intended to sterilize
- reduce microorgs, remove pathogens
- best chem kills in shortest time w/out damaging material
Action of Microbial Agents
- alteration of membrane permeability (cause bigger ‘holes’ in membrane and weaken cell wall)
- damage to proteins (can’t survive without them)
- Damage to nucleic acid (no replication, mutations)
Halogens
- Oxidizing agents
- Iodine (betadine)
- Chlorine
Alchohols
- denature protein, dissolve lipid
- use against fungi and some enveloped viruses
- NO EFFECT on bac SPORES
- 70% ETOH most effective.
Phenol
- discovered by Joseph LISTER (Listerene) for disenfection
- damages cell membrane and inactivates enzymes of microorgs while denaturing protein
- Lysol (cresols)
- Hexachlorophene (bisphenols)
Heavy Metals
- denature protein
- Silver (Ag)
- Silver nitrate in eye of newborns again Neisseria gonorrhea
- Copper (Cu), shock swimming pools, fish tanks, reservoirs to reduce algae growth
- Zinc (Zn): Zinc Chloride in mouthwash, Zinc oxide antifungal in pants and for diaper rash
Aldehydes & Peroxides
Aldehydes: formaldehyde and glutaraldehyde, inactivate proteins by crosslinking functional groups of proteins. Formalin use for embalming
- Ethylene Oxide: gas to denature proteins
- Peroxide: hydrogen and benzoys peroxide
Soap / Detergents
- decrease surfac tension btwn microorg and surface
- Soaps: emulsify oily film on body, carry away oil, debris in de-germing action
- Cationic Detergents: Quaternary ammonium compounds. Dissolve cell membranes of microorgs
Phenol coefficient test (PC)
used to evaluate effectiveness or antiseptic or disinfectant
PC > 1 = chemi is more effective than phenol
PC < 1 = chem less effective than phenol
Antiviral
- inhibit viral growth, NOT KILL
- decrease viral load
- specific antiviral drug used for specific virus.
Antifungal
- meds used to treat fungal infec.
- work by identifying differences between human and fungal cells to kill organism without harming host.
Antiparasitic
treat parasite disease i.e. head lice, scabies, trich, vaginalis, nematodes, cestodes, trematodes, infections protozoa, amoebas
Who discovered PCN (Penicillin)?
Alexander Fleming, 1928
-bactericidal - KILL
Types of Abx
- Broad spectrum: wide range of bac (gm neg and pos)
- Narrow spectrum: specific type of bac
- Superinfection: secondary infection after primary infection is killed
Alcohols have NO effect on
- Bacterial Spores
- non enveloped viruses
The most effective wavelength for microorganisms
260nm
Shorter Wavelength =
higher energy
How do Abx work?
- inhibit cell wall synthesis
- Inhibit protein synthesis
- injure plasma membrane
Types of Abx
Bacteriostatic: slow growth of bac. by:
- inhibit DNA replication
- interfere with metabolism
- inhibit protein synthesis
Bactericidal: kill bacteria by
-prevents cell wall synthesis
Do Viruses have cell walls?
NO, that’s why abx that affect cell wall can not kill viruses.
Vancomycin
inhibit cell wall synthesis
Acyclovir
inhibit DNA or RNA synthesis
Tetracycline
inhibit protein synthesis
Sulfonamides
inhibit synthesis of metabolites
