Identification, Disinfection Flashcards
-streaking culture technique
-serial dilutions culture technique
MacConkey Agar
-selective and differential media
-differentiates lactose utilizers
-red = lactose utilizers
-white = don’t utilize lactose
-selects against gram positive bacteria
how to tell if spores present
-refractile to gram stain – colorless hole in cell
motility test - wet mounts
-direct microscopic observations
-left negative
-right positive
motility test - motility culture media
-soft agar stab
-left nonmotile
-right motile
H, O, K antigens
-H antigens - flagella –> protein
-O antigens - LPS –> polysaccharides
-K antigens - capsule –> polysaccharides or protein
what serological test is used for initial screenings of colonies than may be Salmonella
-slide agglutination
what serological tests do you not need to isolate pathogen for and can use patient’s serum
-ELISA
-latex agglutination
-Western blotting
what is triple iron media used for
-differentiate enteric bacteria based on ability to ferment sugars, produce H2S, produce gas
Triple iron media
-non fermenter
-alkaline slant, alkaline deep
Triple iron media
-non lactose fermenter
-alkaline slant, acid deep
-acids produced can result in orange to yellow color
Triple iron media
-lactose and sucrose fermenters
-acid slant, acid deep
Triple iron media
- non lactose fermenters, H2S producer
-alkaline slant, H2S deep
what is protein degradation
-following hydrolysis of peptide bonds, amino acids are catabolized
deamination
deaminase
desulfurylation
sulfurylase
decarboxylation
decarboxylase
combined tests for biochemcial characteristics
-enterotube
-API20E system
what is a prerequisite prior to testing
isolation of homogenous culture
define decontamination
-cleaning to eliminate risk of infection
-reduction in pathogenic organisms
define disinfection
-elimination of most pathogenic organisms, including spores
define sterilization
-elimination of all living organisms
moist heat
-denaturing of proteins
-autoclave
dry heat
-limited to inanimate heat resistant objects
incineration
-fast, but expensive
-elimination of pathogen contaminated materials (bandages, carcasses, tissues)
ultraviolet radiation
-thymine dimer distorts DNA
-endonuclease cuts out region with thymine dimer
-repair synthesis by DNA polymerase
-DNA ligase seals new strand to old strand
ionizing radiation (ozone)
-x rays, gamma rays
-produce oxygen radical and OH radical from water
-disruption of covalent bonds
-sterilization of inanimate heat sensitive materials
liquid filtration
-average pore size 0.2 um
-bacteria average 0.5 um
-sterilize liquids that are heat sensitive
air filtration
-high efficiency particulate air filter
-99.999% of 0.12 um particles
alkylating chemical agents
-gaseous and liquids
-reactive with carboxyl, hydroxyl, sulfhydryl groups of proteins
-sterilize things sensitive to heat
sonication
-vibrating probe
-bubbles bombard cells and lyse them
define MEC
-minimum effective concentration of a germicide required to achieve advertised microbial activity
what is the gradient of microbial activity on bacteria of disinfectants
gram+ < gram- < acid fast < spore formers
alocohols
denature proteins and solubilize lipids
alkalines
-destroys cell wall and cell membranes
-used on inanimate objects
heavy metals
-poison enzyme activities by interacting with sulfhydryl groups of cysteine residues
oxidizing agents
-halogens – iodine, chlorine
-inactivate enzymes by converting functional SH groups to oxidized SS forms
surface active agents
-induce reaction of surface or interfacial tension
-wetting agents, detergents
-anionic – soaps, fatty acids with negative charge
cationic – quaternary ammonium compounds
phenolic compounds
-membrane disruption and protein denaturation
-phenol no longer used due to toxicity
-lysol
aldehydes
-glutaraldehyde
-ortho-phthalaldehyde
-formaldehyde
what do gross metabolic poisons do
alter permeability, irreversibly denature macromolecules
most commonly used disinfectant
bleach
