CONTROLING MICROBIAL GROWTH: IN VITRO Flashcards
In vitro
Occurrences that happen outside the body
in vivo
Occurrences that happen inside the body
Factors that affect Microbial growth
1.Availability of nutrients
2. Moisture
3.Temperature
4.pH
5. Osmotic Pressure and salinity
6. Barometric pressure
7. Gaseous atmosphere
complete drying process
desiccation
example of Thermophiles
Pyrolobus fumarri
organism that live in >100 deg.
Hyperthemophiles or extremethermophiles
an archaeon organism that live in 113 deg. Celsius
Pyrolobus fumarri
organism that grow in normal body temperature
mesophiles
A group pf psychrophiles that has an optimum growth of 4 deg.
psychotrophs
prefer warm temperatures but can tolerate very cold temperature
psychoduric organisms
bread molds
psychotrops
example of psychoduric organisms
E. coli
thermophiles minimum growth temp.
25 deg.
thermophiles optimum growth temp.
50-60 deg
thermophiles maximum growth
113 deg.
mesophiles minimum growth
10 deg.
mesophiles optimum growth
20-40 deg.
mesophiles maximum growth temp
45 deg.
psychrophiles minimum growth
-5 deg.
psychrophiles optimum growth
10-20 deg.
maximum growth of psychrophiles
30 deg.
types of pH affecting microbial growth
Acidophiles
Alkaliphiles
hydrogen ion of the solution
pH
ph 2-5
acidophile
ph >8.5 and example:
Alkaliphiles, intestine Vibrio cholerae
pressure on the cell membrane outside and inside the cell: where, pressure is equal.
osmotic pressure
The movement of solvent from low solute to high solute.
osmosis
equal concentration of solutes inside and outside the cell
isotonic
no cell movement water
isotonic
concentration of the solute outside the cell is GREATER than than inside.
HYPERTONIC
HYPERTONIC
RBC CRENATION
PLASMOLYSIS (BACTERIAL CELL)
Concentration of the solute is LOWER outside than inside
hemolysis RBC
plasmoptysis (bacterial cell)
halophilic bacteria
vibrio cholerae
BAROMETERIC PRESSURE
piezophiles 14.7 psi
20-21 % Oxygen
78-79% Nitrogen
Obligate Aerobes
5% oxygen
microaerophiles
5-10% Carbon dioxide
Capnophiles
destruction of all microbes including cells, spores and viruses
sterilization
dry hear, steam, under pressure and radiation
physical methods
ethylene oxide gas, formaldehyde
chemical methods
elimination of all pathogens except bacterial spores from non living organism.
disinfection
methods of disinfection
-pasteurization
-disinfectants
-antiseptics
-sanitization
agents that kill organism (bactericida, sporicidal and fungicidal)
microbicidal
inhibits the reproduction of microorganisms, but not necessary killing them
microbistatic
process combines dehydration and freezing
lyophilization
presence of pathogen in blood or tissue
sepsis
absence of pathogen is
asepsis
prevention of an infection
antisepsis
a method to eliminate and exclude pathogen to prevent infection
aseptic technique
who developed aseptic technique?
John Lister
most common type of sterilization used in inanimate object
heat
two factors of heat
temperature and time
the lowest temperature that kills organism within a specified time
THERMAL DEPTH POINT (TDP)
the length of time necessary to sterilize a pure culture at a specified time
THERMAL DEPTH TIME(TDT)
effective sterilization of glassware, metals, oils and waxes.
dry heat methods: Oven Heating/ Baking
the most common method in treating infectious waste in infected animals
incineration
burning of contaminated materials to ashes (300- 400 deg.) hazardous materials (870-980)
incineration
used to control the spread of infectious disease
cremation
faster and more effective than dry heat
moist heat
methods of moist heat
-boiling
-autoclaving
-tyndalization
-inspissation
-pasteurization
destroy vegetative bacteria
boiling
stem pressure: destroy all microbial life
autoclaving
121.5 deg
15 psi
15-20 mins
sterilize media and instrument
132 deg.
30-60 mins.
infectious medical waste
pressure sensitive found in autoclave tapes
Geobacillus stearothermophilus
ampule purple to yellow
process not successful
fractional sterilization
Tyndalization
free circulation of steam at atmospheric pressure
Arnold sterilizer
thickened media through evaporation
inspissation
sterilize high proteins containing media (eg. Lowenstein-Jensen’s media and Loeffer’s serum media)
inspissation
sterilize dairy product and other beverages
pasteurization
types of pasteurization
Low temperature holding (LTH)
High temperature Short time (HTST)
Ultra High Temperature
classical method: batch method 63 deg. for 30 mins.
Low temperature holding (LTH)
flash pasteurization: 72 deg. for 15 see.
High temperature Short time (HTST)
140 deg. for 3 sec or <1 seconds
Ultra High Temperature
methods of choice for sterilization of antibiotic solutions, vaccines, toxic chemicals,radioisotopes, vaccines and carbohydrates.
Filtration
2 types of filtration
depth filters
membrane filters
filters for fibrous granular materials (asbestos)
depth filters
polycarbonate: cellulose acetate
liquid: cellulose acetate
Air : Hepa filter
membrane filters
cold sterilization: shorter wavelength: high intensity energy (eg. gamma rays, Xrays)
Ionizing radiation
Ionizing radiation inidcator
Bacillus pumilus
longer; lower energy
ono ionizing radiation