micro practical

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gram stain
differential stain that distinguishes between bacteria based on the composition of their cell walls.
mordant
a chemical that fixes (makes permanent) the primary stain by combining with it to form an insoluble compound.
gram positive bacteria
have cell walls containing thick layers of peptidoglycan that are believed to help prevent decolorizing during the alcohol wash.
gram negative bacteria
have a much thinner layer of peptidoglycan and an outer membrane rich in lipids.
acid fast
differential stain that distinguishes between bacteria based on the presence of mycolic acid in the cell wall.
Ziehl-Neelsen
acid-fast stain that requires a five minute steaming during the primary staining in order to get the stain into the cells and fixed.
Kinyoun acid-fast stain
mixes a high concentration of phenol with the primary carbolfuschin dye
group a
Easily killed disinfectants includes most vegetative bacteria and enveloped viruses
group b
More difficult to kill Includes the TB bacterium and non-enveloped viruses
group c
very difficult to kill Includes most bacterial spores and the Hepatitis viruses
simple stains
are most useful for determining bacterial morphology
moist heat not under pressure
boiling and live steam where some spores and viruses will survive even several hours of boiling.
dry heat
Items to be sterilized are put into hot air ovens or are directly heated
moist heat under pressure
Accounts for over 90% of all medical and lab sterilization and kills both vegetative cells and spores
concentration of antibiotic, diffusion rate of antibiotic, density of bacteria growth, thickness and viscosity of the medium, temperature and duration of incubation
variables that can affect the test if bacteria is sensitive to an antibiotic
meullar-hinton medium
Clear medium that stays clear, Maintains a stable pH of 7.2,Contains no ingredients known to inhibit or otherwise affect bacterial growth, and contains no ingredients that interact with the antimicrobial agents.
differential medium
is a medium that allows us to differentiate between microorganisms based on the microorganism's biochemistry
color
After incubation of a differential medium, a change occurs in the ____ of either the medium or the colonies, allowing the differentiation of different microorganisms.
selective medium
is a medium that contains one or more components that suppress the growth of some microorganisms without affecting the growth of others
Mannitol fermenting organisms
what grows on a mannitol salt agar
acidic byproducts
On Mannitol-Salt agar, if the bacteria turns from purple to yellow, it's due to the ______ of bacterial growth.
7.5 %
Mannitol salt agar contains _____ sodium chloride
sodium chloride
prevents the growth of most microorganisms, and mannitol and neutral red
mannitol and neutral red
allow identification of mannitol fermenting organisms
alpha
hemolysis of incomplete clearing and greening of agar
beta
hemolysis of complete clearing (you can read sheet of paper through it)
gamma
no hemolysis reaction
bile esculin agar
Used primarily to differentiate Enterococcus from Streptococcus.
medium/agar
basic materials needed for growing/studying microorganisms, provides nutrients and water, and liquids are called broths and solids
inoculating loop
looped wire used to transfer bacteria from one media to another, inoculate media, or prepare slides and smears of bacteria
incubators
provide the proper environment for bacterial growth that is kept at an optimal temperature for growth and proper gas concentrations
bacinterators
used for heat sterilization of inoculation loops
stains
enable visualization of bacteria under microscopes and allows easier assessment of microscopic morphology
material data safety sheets (MSDS)
describe the dangers associated with any chemical with which you might work
antimicrobial agents
agents that kill microbes
disinfectant
an agent that kills microorganisms on an inanimate object. Spores may not be killed
antiseptic
an agent that renders microorganisms harmless by killing them and preventing their growth
sterilization
the destruction of all microorganisms, including spores
-cide
an agent that kills a class of microorganisms
-static
an agent that prevents the multiplication of a class of microorganisms
fomite
non-living, inanimate object that can serve to transfer microorganisms
heat
kills cells by denaturing proteins and nucleic acids and by breaking down cell membranes
heat sterilization
temperature and times are the two most important criteria in ___ ____
thermal death point
lowest temp required to sterilize a pure culture within a set time of 10 minutes
thermal death time
time required to sterilize a pure culture at a given temperature
moist under pressure, moist not under pressure, and dry
three types of heat methods
260 nm
ultraviolet light is highly germicidal at wavelengths of ___
filtration
effective means of sterilizing most liquids and gases
time, temp, pH, microorganisms
chemical methods rely on the factors of ___,___,___,___ for efficiency
solid media
used to isolate and separate bacteria from each other.
blood agar
a differential medium that differentiates the microorganisms based on the hemolysins they produce
phenylethyl alcohol agar
a selective medium that inhibits the growth of gram negative organisms, allowing isolation of only gram positive organisms
staphylococci
grape-like clusters that are present in the normal microflora of our skin, throat, upper respiratory, and the environment.
streptococci
long chains of cocci present in microflora of skin, and upper respiratory tract, and one case of intestinal tract
beta hemolysis, positive coagulase, golden yellow colonies, fermented MSA
(staphylococci) how does staph aureus differentiate from s.epi and s saprophyticus?
s. saprophyticus
staphylococcus that is resistant to novobiocin antibiotic
antibiotics
compounds produced by the metabolic reactions of bacteria and fungi to either kill or prevent the multiplication of other microbes
selective toxicity
antibiotic interferes with or disrupts a biochemical pathway or cellular organelle present in the microbe but not in the cells of the cell producing it
yes
are saphrophytic mycobacteria acid-fast?
no
does the presence of acid-fast organisms in a clinical specimen always suggest serious clinical disease?
infection or cancer
what kind of clinical situation would a direct smear report from the laboratory be urgent importance?
gram stain & acid fast
two types of differential stains
mordant
the function of iodine solution in gram stain is _____
turbidity & color change
what are some signs of growth in a liquid medium
streak dilution technique
diluting down the bacteria to show the growth of single colonies
coagulase
a bacterial enzyme that causes blood or plasma to coagulate
resistant to novobiocin
s. epi & s. sapro are distinquished from eachother because s. sapro is ___ ____
urine
from what specimen type would s. sapro most likely be isolated
blood enriched media, low O2, high CO2, and 35* C
what kind of culture media, atmospheric, and incubation conditions are best for cultivating streptococci
beta
what type of hemolysis is displayed by streptococci that are most pathogenic for human beings
crystal violet (1min) -> water -> iodine (1min) -> water--> decolorizer(10-20sec) -> water -> counterstain w/ safranin -> water -> blot water
gram stain process
carbolfuschin 5 mins -> water -> decolorize with acid-alcohol -> water -> counterstain kinyoun brilliant green( 30 sec) -> water -> blot water
acid fast staining process
sediment, pellicle, ring, turbid, flocculent
growths in broth media
circular, rhizoid, irregular, filamentous, spindle
shapes of bacteria
entire, undulate, lobate, curled, rhizoid, filamentous
margins of bacteria
flat, raised, convex, pulviniate, umbonate
elevations of bacteria
pinpoint, small, moderate, large
sizes of bacteria
smooth or rough
textures of bacteria
glistening or dull
appearance of bacteria
opaque, translucent, transparent
optical property of bacteria
filiform, echinulate, beaded, effuse, arborescent , rhizoid
growth on agar slants of bacteria
index case
the first identified case in a group of related cases of a particular communicable or heritable disease.
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