Control of Microbial Growth pt 2

*ethanol
*isopropanol
*easy to obtain, inexpensive, rapid evaporation (limits contact time)

*high level
*intermediate level
*low level

all organisms except high levels of of bacterial spores or prions

*mycobacteria, most viruses and bacteria

*some viruses and bacteria

Ethylene oxide, glutaraidehyde, formaldehyde

phenolics and halogens

*alcohols, quaternary ammonium compounds

*phenol coefficeint test
*use-dilution test

*all chemical agents compared to phenol chemical agent affect on bacteria
(#'s demonstrate how many more times it is effective)

*Aldehydes are high level
*inactivate proteins by cross-linking with functional groups
*considered a sterilant

True
*Aldehyde

*Glutaraldehyde
*Formaldehyde

*protein denaturation
*crosslinking proteins functional groups

*Ethylene oxide
*Cholorine Dioxide
*Hydrogen Peroxide Vapor (HPV)

*Halogens
*Peroxygens
*Phenol (and derivitives)
*Biguanides

*Intermediate Disinfectant
*oxidizing agent

*chlorine and iodine

*intermediate disinfectant
*oxidizing agent
*Ozone O3
*H2O2
*peracetic acid

*phase and concentration

*intermediate disinfectant
*disrupts plasma membrane
*inactivates enzymes
*denatures proteins

*Phenolics
*Lysol
*Bisphenols
*Hexacholorphene
*Triclosan

*disrupts plasma membrane due to amphipathic nature

Chlorhexidine

*low level disinfectant
*denatures proteins and dissove lipids
*ethanol and isopropanol

ethanol is used as the solvent instead of water in the low level disinfectant
*helps improve disinfectant properities of solute

60-90% range (no growth after 10 seconds)

*surface active agents
*considered mechanical removal of microbes

*soap (degerming)
*acid-anionic detergents (sanitizing)
*Quarternary ammonium compunds (cationic detergents) Bactericidal

*sanitizing (disrupt plasma membrane)

*bactericidal (denature proteins, disrupts plasma membrane)

*oligodynamic action (not fully understood)
*denatures proteins

*Ag, Hg, Cu

*acts as long acting antimicrobial

*Organic acids
*nitrite
*Antibiotics

*inhibit metabolism of microbes
*control molds and bacteria in foods and cosmetics

*sorbic acid
*benzoic acid
*calcium propionate

*prevents endospore germination

Nisin and Natamycin

Selective toxicity

*characterisitcs of the organisms
*concentration of the agent
*time of exposure

True

*Prions
*they are not alive (protien) so resistant to digestion

viruses with lipid envelope
*possess no machienary to repair damage to envelope, contain no phospholipid protection

bleach and cyclohexidine

*gram neg have two membrane system than pos one mem

*thick cell wall helps with resilence to water environments (hypotonic solutions)

*alcohols
*glutaraldehyde

*disk-diffusion method
*disk diffusion assays

*bacterial growth (lawn) on agar surface
*(filter paper discs soaked in antibiotic material)
*evaluate zones of inhibition

*Mueller Hinton agar plate
*lawn of bacteria
*observe zones of inhibition (use standardized chart to evaluate sensitivity) and MIC values

minimum inhibitory concentration

*the effect of two drugs (together) is greater than the effect of either alone

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

Minimum inhibitory concentration
*lowest antibotic concentration that inhibits bacteria growth

*minimal bacteriocidal concentration
*the lowest concentration where 99.9% of bacteria are killed

*minimun dose per kg of body weight that stops growth

*maximum dose tolerated by the patient

*ratio of toxic dose to therapeutic dose

*higher=safer the drug