CHAPTER 3: Lesson 10: Culture Methods Flashcards
A population of bacteria grown in the laboratory.
culture
This contains only one single type
pure culture
It contains two or more different bacteria
mixed culture
If a bacterial culture is left in the same media for too long, the cells use up the available nutrients, excrete toxic metabolites, and eventually the entire population will die. Thus bacterial cultures must be periodically ____________, to new media to keep the bacterial population growing
subcultured
This is used to obtain a pure culture of an
infectious agent, and also for studies leading to the identification of the pathogen.
subculturing
This means using practices and procedures to prevent contamination from pathogens.
Aseptic technique
It involves applying the strictest rules to
minimize the risk of infection.
Aseptic Technique
Culture methods
- Streak plate method
- Lawn culture
- Stroke Culture
- Stab culture
- Pour plate culture
- Shake culture
- Liquid cultures
The most effective way to isolate a single type of
bacteria from a source that contains many.
Streak plate method
Method used by diluting the individual cells by
spreading them over the surface of an agar plate using a platinum or inoculating
loop of 2–4 mm diameter.
Streak Plate Method
Size of a platinum or inoculating
loop used in streak plate method.
2–4 mm diameter
The piles of bacterial cells
observed after an incubation period.
colonies
In the Streak Plate Method, the inoculated culture plate is incubated at _________ overnight
for demonstration of colonies.
37°C
In the Streak Plate Method, this growth occurs at the primary inoculum.
confluent growth
Also called as carpet culture
Lawn culture
this method is used for Antibiotic susceptibility testing by disk diffusion method
Lawn culture
This method is used for Bacteriophage typing.
Lawn culture
This is used for preparation of bacterial antigens and vaccines.
Lawn Culture
This culture are prepared by flooding the surface of the plate with a liquid culture or suspension of the bacterium, pipetting off the excess
inoculum and incubating the plate
Lawn culture
It provides a uniform growth of the
bacterium.
lawn culture
It provides a pure growth of bacteria for carrying
out slide agglutination and other diagnostic tests.
Stroke culture
It is carried out in tubes usually
containing slanted nutrient agar slopes.
Stroke Culture
This method is used for mainly for demonstration of gelatin
liquefaction.
Stab culture
This method is used for demonstration of oxygen requirement of the bacterium under
study.
Stab Culture
This Method is used for the maintenance of stock cultures.
Stab Culture
This method is used to study motility of bacteria in
semisolid agar.
Stab Culture
This is used to determine approximate
number of viable organisms in liquids, such as water or urine.
Pour plate culture
It is used to
quantitate bacteria in urine cultures and also to estimate the viable bacterial
count in a suspension.
Pour Plate Culture
This method is carried out in tubes, each containing 15 mL of
molten agar.
Pour Plate Culture
Pour Plate Culture is carried out in tubes, each containing _______ of
________.
15 mL
molten agar
The molten agar in tubes in the Pour Plate Culture is left to cool in a water bath at _____.
45°C
In the Pour Plate Culture, after
overnight incubation of these Petri dishes at ______, colonies are found to be
distributed throughout the depth of the medium, which can be counted using
a _________.
37°C
colony counter
A deep culture of agar or gelatin through which the inoculum is
evenly distributed by shaking before the medium is solidified.
Shake culture
This method is used
chiefly for the demonstration of anaerobic colonies.
Shake Culture
It is made by melting nutrient agar in a test tube.
Shake Culture
This method is used for blood culture and for sterility.
Liquid cultures
This method is used for dilution in the medium,
Liquid Culture
This method is used for or large yields culture.
Liquid Culture
It does not provide a pure culture from mixed inocula—the major disadvantage, nor
identify a bacteria.
liquid cultures
Incubation of cultures at this temperature is standard practice in the
culture of bacteria pathogenic to man.
37°C
Brucella abortus and capnophilic streptococci, require extra of this element in the air in which they are grown.
CO2 or carbon dioxide
These organisms grow better in air supplemented with 5 to 10
percent CO2.
pneumococcus and gonococcus
pneumococcus and gonococcus grow better in air supplemented with how many percent of CO2?
5-10%
For cultivation of aerobes the incubation is done in an incubator under normal atmospheric condition.
Aerobic Culture
It require incubation without oxygen and differ in their
requirement and sensitivity to oxygen.
Anaerobic bacteria
It will not grow from small
inocula unless oxygen is absent and the Eh of the medium is low.
Obligate anaerobes
METHODS OF ISOLATING PURE CULTURES
- Surface plating
- Use of selective, enrichment or indicator media
- Selective treatment of the specimen before culture
- Use of selective growth conditions
- Separation of motile from non-motile bacteria can be effected using Cragie’s tube
- Animal inoculation
- Filters
a method routinely employed in clinical bacteriology and enables
the isolation of distinct colonies which may be picked out, if necessary for further
purification and study
Surface plating
widely used for the isolation of
pathogens from specimens such as feces, with varied flora
Enrichment, selective and indicator media
_________ such as ________ for the diphtheria
bacillus, have been devised so that, the majority of organisms likely to be associated
with those for which the media are used will not grow, and the isolation of pure
cultures is thus facilitated
Selective media
tellurite media
Selective media such as tellurite media for this kind of bacteria, have been devised so that, the majority of organisms likely to be associated
with those for which the media are used will not grow, and the isolation of pure
cultures is thus facilitated.
diphtheria
bacillus
This media favor the multiplication of particular species as a step towards their isolation in
pure culture.
Enrichment media
Example of Enrichment Media
selenite broth
Enrichment media such as selenite broth is for what type of sp?
Salmonella
sp
This media contain ingredients that change in appearance with particular
organisms and so assist their isolation.
Indicator media
Indicator media, such as Willis and Hobbs medium is for what specie?
Clostridium sp
Example of Indicator Media
Willis and Hobbs medium
Willis and Hobbs medium is an example of what media?
Indicator Media
Used to separate spores from vegetative bacilli but does not guarantee that
spores will germinate under subsequent cultural conditions.
Heating at 65°C for 30 minutes or at higher temperatures for shorter periods
This method is useful for the isolation of tetanus bacilli from dust and
similar source.
Selective treatment of the specimen before culture
Heating at 65°C for 30 minutes or at higher temperatures for shorter periods.
Selective treatment of the specimen before culture
This method is the standard
practice for the isolation of tubercle bacilli from sputum and other clinical specimens,
by treatment with alkali, acid or other substances to which most commensals are
susceptible but tubercle bacilli are resistant.
Pretreatment of specimens with appropriate bactericidal substances
Separation of bacteria with different temperature optima
Use of selective growth conditions
The temperature
and atmosphere chosen for a culture automatically preclude the growth of many bacteria.
Separation of bacteria with different temperature optima
Incubation temperature used for most medically important bacteria, is too warm
for some air contaminants, which subsequently appear as colonies when plates are
kept at room temperature.
37°C
Some pathogens are selectively favoured by growth at what temperature?
above 37ºC
What bacteria grow at 60ºC?
thermophilic bacteria
Only thermophilic bacteria grow at what temperature?
60ºC
Obligate aerobes and
anaerobes may be separated by cultivation under aerobic or anaerobic conditions.
Cultivation under aerobic or anaerobic conditions
_________ will not grow in air and most __________ grow less
vigorously under anaerobic than under aerobic conditions
Strict anaerobes
facultative anaerobes
This consists of a tube of semisolid agar, with a narrow tube open at both
ends placed in the center of the medium in such a way that it projects above the level of the agar.
Separation of motile from non-motile bacteria can be effected using Cragie’s tube:
Separation of motile from non-motile bacteria can be effected using what?
Cragie’s tube
This also serves the same purpose, inoculation being performed in one
limb and the subculture taken from the other.
U-tube
This method can also be used to obtain
phase variants in Salmonella species.
U-tube
U-tube can also be used to obtain
phase variants in what spp?
Salmonella spp
Pathogenic bacteria may be isolated from mixtures by inoculation into
appropriate animals due to the fact that laboratory animals are highly susceptible to
certain organisms.
Animal inoculation
example of animal that is highly susceptible to
certain organisms line pneumococcus
mouse
Mouse is highly susceptible to
certain organisms like what?
Pneumococcus
Animal inoculation
- Pnemococcus
- Anthrax bacilli
- Tubercle bacillus
If a mixture of organisms containing the pneumococcus, e.g. in sputum, is inoculated subcutaneously into a mouse, the animal dies because of what?
pneumococcal septicemia
If a mixture of organisms containing the pneumococcus, e.g.
in sputum, is inoculated subcutaneously into a mouse, the animal dies of
pneumococcal septicemia in how many hours?
12 to 48 hrs
Pnemococcus can be obtained in
pure culture from the ________.
heart blood
It can be distinguished from other aerobic
sporulating bacilli by inoculation into mice or guinea pigs.
Anthrax bacilli
It produces a
fatal septicemia and may be cultured pure from the heart blood.
Anthrax bacilli
Anthrax bacilli can be distinguished from other aerobic
sporulating bacilli by inoculation into what animals?
mice or guinea pigs
Anthrax bacilli produce a
_________.
fatal septicemia
Anthrax bacilli produce a
fatal septicemia and may be cultured pure from where?
heart blood
This can be isolated from
contaminating organisms by inoculation of an infected specimen into a guinea pig.
.
Tubercle bacillus:
Tubercle bacillus can be isolated from contaminating organisms by inoculation of an infected specimen into a what animal?
guinea pig
Bacteria of differing sizes may be separated by the use of these.
Filters
These are widely used for separating viruses from bacteria.
Filters
