CH 13 The control of Microbial Growth

Removal of ALL microbial life

Removal of pathogens

removal of pathogens from living tissue

absence of infection or infectious agents

methods which prevent microbial contamination and infection

infection resulting in systemic inflammation

removal or reduction in microbes from an area

lower microbial count on eating utensils

kills microbes

Inhibiting, not killing, bacteria

Number of microbes, Enviroment (organic matter, temperature, biofilms), Time of Exposure, Microbial Characterisitics

Heat, Filtration, Cold, Desiccation, Osmotic Pressure, Radiation

Lowest tenperature at which all cells ina culture are killed in 10 mins

Time to kill all cells in a culture at a given temperature

Time to kill 90% of a population under specific conditions

Moist heat, Pasteurization, Dry heat- direct flaming, incineration, hot-air sterilization

denatures protiens. ex- autoclave- steam under pressure

reduces spoilage organisms and pathogens- equivalent treatments 63C for 30 min, 82.2 for 22 sec

kills by oxidation or denaturation; flaming, incineration, hor-air sterilization

removes microbes- ,2 um

inhibits microbial growth- refrigeration, deep freezing, and lyophilization

denatures protiens

prevents metabloism- does not nessarily kills organisms

causes plasmoylsis

damages DNA; two types- Ionizing (X-rays, gamma rays, electron beams) and Nonionizing (UV- causes thymine and cytosine dimers in DNA)

Concentration of disinfectant, organic matter, pH, time

toxicity, material compatibility (corrosiveness), residue, order, storage and stability, enviromental risk, surface tension

phenols/phenolics, halogens, alcohols, heavy metals and their compounds, surface-active agents, quarternary ammonium compounds, gaseous chemosterilizers, and chemical food preservation

Vegatative bacterial cells, myobacteria, spores, fungi, viruses

Ethylene oxide, glutaraldehyde, formaldehyde- work agaisnt all categories

Phenolics, halogens- work against everything else except spores

Alchols, quarternary ammonium compounds- work agaisnt vegatative cells, fungi, and some viruses

Phenol coefficient tes- compare to phenol; Ude-dilution test

Inactivate protiens by cross-linking with functional groups (OH, COOH, NH2), Sterilant (in high enough doses)

Glutaraldehyde, Formaldehyde

Protien denaturation and crosslinking

Ethylene oxide (kills fungus), Chlorine Dioxide, Hydrogen Peroxide Vapor (HPV; not same as Common HP)

Strong Oxidizer; Chlorine, Iodine, Bleach (hypochlorous acid)

Oxidizing Agents; Ozone O3. Hydrogen peroxide (h2o2), peracetic acid

disrupt plasma membranes, inactivates enzymes, denatures protiens

Phenolics, Lysol, Bisphenols, Hexachlorophene, Triclosan

Disupt plasma membrane; ex. Chlorhexdine

Ethanol, isopropanol

Dentaure protiens, dissolve lipids

mechanical removal of microbes

soup- degerming; acid-anionic detergents- sanitizing disrupt plasma membrane; Quartnery ammonium compounds- Bactericidal, denature protiens and disrupt plasma membrane

Oligodynamic action; dentaures protiens/inhibits growth; ex. Ag, Hg, Cu

Prion, Endospores of bacteria, Mycobacteria, Cysts of protozoa, Vegatative protozoa, Gram-negative bacteria, Fungi (including most fungal spores), Viruses without envelopes, Gram-positive bacteria, Viruses with lipid envelopes

Organic Acids, Nitrite, Antiboitics

Inhibit metabolism; ex. sorbic acid, benzoic acid, calcium propionate; control molds and bacteria in foods and cosmetics

prevents endospore germination

Nisin and Natamycin prevent spoilage of cheese

occurs when the effect of two drugs together is greater than the effect of either two alone

occurs when the effect of two drugs together is less than the effect of either alone

Lowest concentration at which 99.9% of bacteria are killed

lowest antibiotic concentration that inhibits bacterial growth

Minimum dose per kg of body weight that stops growth

Maximum dose tolerated by the patient

the ratio of the toxic dose to the therapeutic dose. The higher the value the safer the drug