Midterm
Microbiology 222 with Lee at Brigham Young University
About this deck
By: Rachel Farnsworth
Created: 2011-12-03
Size: 303 flashcards
Views: 29
Created: 2011-12-03
Size: 303 flashcards
Views: 29
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj
Sign up (free) to study this.
who coined the word animacules?
Antonie van Leeuwenhoek
Leeuwenhoek years
1632-1723
who is the father of microbiology (specifically bacteriology and protozoology)?
Antonie van Leeuwenhoek
Parts of the light microscope
base
source of illumination
condenser / iris diaphragm
stage and stage opening
objectives
coarse adjustment
fine adjustment
ocular lens
lamp
produces visible light to illuminate the specimen
condenser
collects light and directs it through the stage opening (converges or focuses the rays of light to a single point)
iris diaphragm
regulates the amount of light available to the objective lens
factors that affect microscope function
resolving power
numerical aperture
magnification
working distance
resolving power
the ability of a microscope to differentiate two closely spaced objects as being distinct from one another
resolving power of a light microscope
.2 micrometers
how to calculate resolving power
resolving power = wavelength of light / (2 x numerical aperture)
with wavelength of visible light (500 nm), the resolving power is .2 micrometers
what happens to resolving power as the magnification of the objective lens increases?
increases
use of a shorter wavelength of light increases...
resolving power
resolving power depends upon
wavelength and numerical aperture
and also magnification i guess
numerical aperture
the ability of a lens in a light microscope to gather light
how to calculate numerical aperture
numerical aperture = i sin
i is the refractive index of air
sin is 1/2 the angle of light entering the microscope lens
what is the numerical aperture of the oil immersion lens?
1.25
what happens to light rays as they travel through media like glass and air?
they are bent or refracted
refractive index
indicates the amount of bending of light rays
refractive index of cedar wood oil
1.56
what does immersion oil do?
minimizes refraction producing a more clearer image with more detail
total magnification
product of the magnification of the ocular lens (10x) and the objective lens
total magnification of the low power objective
100x
total magnification of the high power objective
400x
total magnification of the oil immersion objective
1000x
working distance
the distance from the end of the objective lens to the top of the slide when the specimen is in focus
higher magnification means
shorter working distance
parfocal
a specimen in focus under the low power objectives should be nearly in focus under the oil immersion objective as well
Leica DM6000 B
automated microscope
has a powered stage, automatically returns slide to specific coordinates, and there can be multiple coordinates
bacillus megaterium
gram positive bacillus in chains
produces endospores
streptococcus pyogenes
gram positive cocci in chains
group A strep
causative agent of streptococcal pharyngitis
strep throat agent
staphylococcus aureus
gram positive cocci in clumps "bunch of grapes"
responsible for pyogenic (pus forming) infections
escherichia coli
gram negative, short bacilli
member of the resident flora of the GI tract
some produce toxins and are pathogenic (0157h7)
what objective is best to see images?
oil immersion
three locations where bacteria are found
fomites
living surfaces
dust particles in the air
fomite examples
drinking glasses
silverware
plates
tissues, towers, combs, brushes, doorknobs, buttons, countertops, clothing, tables, floors
examples of living surfaces
humans- skin, mucous membranes, GI tract
normal flora
normal flora
microorganisms comprise part of the normal flora found in the human body
some members of the normal flora are opportunistic pathogens and can cause disease if conditions are favorable
ways bacteria can spread
aerosols
food born infections
water borne infections
aerosols
droplet airborne infections
can transmit diseases like TB and the common cold
food borne infections
food handlers can transmit disease organisms like hep A and salmonella
contaminated utensils (silverware, glasses, dishes)
improperly cooked/processed foods- botulism!
water borne infections
inadequate water filtration
inadequate waste water treatment
contamination of drinking water after treatment (leaking pipes)
communal bathing
what are some bacteria that cause water borne diseases?
vibrio cholerae- cholera
campylobacter jejuni- acute gastroenteritis
salmonella - salmonellosis, typhoid fever
shigella- shigellosis
e coli- acute gastroenteritis
what are some viruses that cause water-borne diseases?
hep A virus- infections hepatitis
norwalk virus- acute gastroenteritis
poliovirus- poliomyelitis
what are some protozoa that cause water-borne diseases?
giardia iamblia- giardiasis
schistosoma- schistosomiasis
entamoeba histolytica- amebic dysentery
what are some toxin producers that cause water-borne diseases?
gonyaulax - paralytic shellfish poisoning
gambierdiscus- fish poisoning
two major categories of human infections spread by fomites to humans
skin/mucous membrane infections
gastrointestinal infections
is human skin sterile?
no
the majority of microorganisms are...
non pathogenic
do not cause disease
asepsis
a condition free of viable organisms
aseptic techniques
avoid contamination of established cultures
avoid contamination of the environment with cultures that are being manipulated
autoclave or steam sterilization
uses steam under pressure
sterilization of culture media, reagents, and lab tools
dry heat
uses an oven to generate hot dry air
sterilization of glassware and moisture sensitive preparations
filter sterilization
uses a membrane to trap microorganisms
sterilization of heat sensitive liquids
flame sterilization
uses an open flame to incinerate microorganisms
sterilization of tools like inoculating loops and needles
liquid media
broth in tubes and flasks
nutrient broth
solid media
contains agar as a solidifying agent
agar medium in Petri dishes
agar slants and deeps in tubes
nutrient broth/agar
peptone
beef extract
distilled water
agar
pure culture
a culture where only one type of cell is present
pure culture techniques
the ability to grow bacteria and other microorganisms as pure cultures requires skill in aseptic transfer techniques
inoculating loop
used to transfer a culture of microorganisms to an agar medium in a petri dish, to an agar slant, or to another liquid medium
inoculating needle
used to transfer a culture by stabbing to a semisolid medium like motility agar
sterilization of the inoculating loop or needle
hold it in the flame until red hot
cool for a few seconds
flaming an open culture tube
flame the mouth of the culture tube before and after transfer
helps prevent contamination from dust in the air
growth in a broth is detected by
cloudiness in the medium
growth on a slant is seen as
a film of material on the agar surface
growth in an agar deep is detected by
some cloudiness in the agar at the stab line
bacteria are
small and colorless
coloring agents or dyes are applied to bacterial smears to
provide contrast and make the bacterial cells more visible
who was the first to discover the staining technique?
Leeuwenhoek (1600s)
used Saffron to stain muscle fibers so that he could observe them under a microscope
who developed the first synthetic dye?
William Perkins
1856
Who developed the gram stain?
Hans Christian Gram, 1884
worked in a morgue, wanted to enable bacteria to be seen more readily in stained sections of lung tissue
simple stain
requires only a single stain to be applied
a bacterial stain is most commonly
a basic dye
what do simple stains show?
cell morphology and arrangement
do not distinguish between different types of bacteria
a stain or dye is composed of
a colored portion (chromophore) and an opposite charged particle
basic dye
consists of a positive chromophore and a negative ion
acidic dye
consists of a negative chromophore and a positive ion
charge of bacteria
negative on the outside, so they have an electrostatic attraction to basic dyes (positive chromophore)
basic dyes
crystal violet, safranin, methylene blue, carbolfuchsin
heat fixation
once the smear has dried the slide must be heat fixed
heat fixation rapidly kills the cells with minimal distortion and attaches the cells to the slide
what does the gram stain do?
divides bacteria into two primary groups based on cell walls tructure
gram positive bacteria
retain the primary dye crystal violet and stain purple
contain a cell membrane and a thick layer of peptidoglycan
more sensitive to antimicrobial actions (penicilin, detergent, basic dye)
teichoic acids in cell wall (help with cell wall development)
acidic charge on cell surface
gram negative bacteria
decolorized by acetone or alcohol and are stained pink by the counterstain safranin
thin layer of peptidoglycan
two membranes (cell membrane, outer layer of LPS)
outer membrane- contains endotoxin
more resistant to antimicrobials
thicker wall overall
how does the gram stain help in diagnosis of disease?
preliminary clinical identification of many pathogens
rule out other possible causes of infection
how to know if you have a UTI with gram stain
if a gram stain of urine shows more than 100,000 coliforms of e. coli per mL, you have a UTI
what is found in gram stains that indicates meningitis?
neisseria meningitidis in spinal fluid
what is found in gram stains that indicates gonorrhea?
n. gonorrhoeae in a urethral exudate
primary stain of gram stain
flood with crystal violet for a minute then rinse
dye settles into peptidoglycan of both types
gram positive retain it better because they have thicker peptidoglycan
mordant of gram stain
iodine
applied after primary stain
1 minute, then water
everything stays the same color
makes the crystal violet stay in the gram positive
decolorizer in the gram stain
alcohol and acetone
15 seconds
removes crystal violet from gram negative
alcohol shrinks pores of gram positive so the color isn't easily removed
counterstain of gram stain
safranin
1 minute, rinse
gram negatives are pink
why do we like the gram stain?
it is cheap, quick and offers evidence for presence of problem organisms
the gram reaction of bacteria isa a ___ characteristic
fixed
what type of bacteria do not stain uniformly with the gram stain?
mycobacterium
what do mycobacteria have on them?
waxy lipid covering called mycolic acid
mycolic acid
resists the entry of crystal violet into the cell and produces a gram-variable result
primary stain of acid fast
carbol fuchsin
use steam to force into cell wall!
mycolic acids in the cell wall hold the stain tight and keep acid alcohol from decolorizing the cell
decolorizing agent in acid fast
acid-alcohol
bacteria that retain the primary dye after decolorization are pink and referred to as acid fast
non acid fast cells like staph are decolorized when the acid alcohol is applied
counterstain of acid fast
methylene blue
stains non acid fast cells
diseases caused by mycobacterium
buruli ulcers
leprosy
tuberculosis
endospore
oval, metabolically inactive structure that is formed within a bacterial vegetative cell
endospore formation is not a method of
cell division
spores are highly resistant to
drying, freezing, UV light, high heat, boiling water, many chemicals and disinfectants
what helps endospores be more resistant and dormant?
calcium and dipicolinic acid
they are present in high concentrations
vegetative cells
metabolically active
more sensitive to drying, freezing, UV light, high heat, boiling water, chemicals, disinfectants
two genera of bacteria that produce endospores
bacillus - gram positive, AEROBIC rods
clostridium- gram positive, ANAEROBIC rods
location of endospores
the location of the spore in the vegetative cell does not change for a given bacterial cell
clostridium tetani have spores at the end of the cell
only one spore forms in a bacterial cell
sporogenesis
triggered by a reduction in carbon or nitrogen sources (unfavorable environment)
during sporogenesis, a multilayered spore wall is formed inside the original vegetative cell
sporangium
original vegetative cell
germination
the process that occurs when an endospore changes into a metabolically active vegetative cell
occurs when endospores are in a medium and physical environment that is favorable for growth
endospore stain procedure
smear flooded with malachite green (primary)
stain forced into spore with steam or heat
decolorizer is water
counterstain safranin applied
colors in endospore stain
sporangium- pink
spore- green
3 forms of anthrax
cutaneous, pulmonary, intestinal
anthrax spores can remain viable in soil for hundreds of years
Clostridium tetani
tetanus- lock jaw
spore producers give off toxins that cause potentially fatal paralysis
transmission occurs when spores accompany deep puncture wounds
spores are found in soil
clostridium difficile
antibiotic associated colitis
pseudomembraneous colitis
clostridium botulinum
infant botulism
most common type of botulism in the US
infants are at risk due to immature intestine and microbial flora
spores in honey, dust, and soil
spores give off a neurotoxin causing flaccid paralysis
capsule
an additional covering around the outside of the cell
capsules are usually composed of polysaccharide
observation of the capsule
requires a special stain technique to be visible
many bacteria produce capsules, but may not express them when grown in standard culture media
how do capsules enhance virulence?
interfere with phagocytosis by macrophages
promote infection by adhering to host cells
gram negative encapsulated bacteria are more resistant to the lethal action of complement (causes lysis of cells) and other serum factors
enhance resistance to lethal actions of heavy metals, dehydrating, and attack of bacterial viruses
Quellung test
capsular swelling in the presence of specific antibody
valuable lab test for the sero-identification of specific encapsulated bacteria
capsule stain procedure
mix culture with India ink and spread
stain with crystal violet
capsule is a clear bright halo
background i stained dark by india ink
true motility
directed motion of bacteria
energy is expended
brownian motion
random back and forth jiggling motion due to collisions of water molecules with the cells
cells don't go anywhere
flagella
long, whiplike structures that extend beyond the surface of the cell and glycocalyx and propel the cell through its environment
composed of flagellin
enough variation to classify into groups called serovars
atrichous
bacteria that lack flagella
monotrichous, polar flagella
bacteria that have a single flagellum
peritrichous
bacteria with flagella distributed around the cell surface
amphitrichous
bacteria with a single flagella at each end
lophotrichous
bacteria with a cluster of flagella at one end
chemotaxis
motile bacteria have the ability to flee from a harmful environment or move toward a favorable environment where food or light is available
chemoreceptors
detect positive chemical signals that trigger counterclockwise motion of the flagella so that bacteria swim in a straight line
if the signal is negative, flagella turn clockwise and bacteria will tumble
three methods to demonstrate motility
flagella stain
hanging drop preparation
culture
flagella stain
observe stained flagella
requires mordants to thicken flagella
hanging drop preparation
observe living bacteria
culture of flagella
stab inoculation of bacteria into motility agar medium in tubes (observe swarming that occurs during incubation)
micrococcus lutea
non motile
pseudomonas aeruginosa
motile, strict aerobe
proteus vulgaris
motile, facultative anaerobe
motility is seen as...
cloudiness in the agar, and as spreading growth at the surface of the agar
how does motility contribute to the pathogenesis of an organism?
facilitates attachment to host tissues
what is the first step in the identification of an unknown microorganism?
gram stain
next step in identifying an unknown?
isolate pure cultures (streak plate or tube dilution techniques, or selective and differential media)
characteristics that are helpful in identifying unknown bacteria
staining
morphoogy and cell arrangement
motility
pigment formation
oxygen requirements
bacillus subtilis
gram positive bacteria
bacilli in chains
staphylococcus aureus
gram positive bacteria
cocci in clumps
micrococcus lutea
cocci in clumps and groups of four
gram positive bacteria
escherichia coli
short bacilli
gram negative bacteria
klebsiella pneumonia
bacilli
gram negative bacteria
pure culture
contains only a single type of organism
can also exist in broth culture
colony
a group of bacteria growing in or on an agar medium
a pure colony
arises from a single bacterium thru cell division
streak plate technique
small inoculum of bacteria is streaked over the surface of agar
spatially dilutes the culture, cells are separated, descendents form colonies
each colony represents a pure culture
loop dilution technique
loopful of bacteria from a mixed culture is serially diluted into tubes of melted agar medium
reduces the number of cells and separates the cells so that isolated colonies are observed after incubation
selective media
favor the growth of distinct microorganisms, while inhibiting others
differential media
distinguish microorganisms that have a defined metabolic process from those that lack the process
uses of selective and differential media
selective and differential media are used to isolate specific microorganisms from mixed cultures
a culture medium can be both selective and differential
nutrient agar
nonselective
peptone, beef extract, agar, distilled water
supports the growth of a wide variety of microorganisms including bacteria and yeasts
MacConkey Agar
selective, differential
peptone, proteose peptone, lactose, bile salts, NaCl, agar, neutral red, crystal violet
bile salts inhibit gram positive, favor gram negative
gram negative turn red because they ferment lactose to acid
other bacteria are clear because they can't ferment lactose
phenylethanol agar
selective
casein, soybean meal, NaCl, phenylethyl alcohol, agar, sheep blood
used to select for the growth of gram positive cocci such as streptococci and staphylococci
generally gram negative bacteria don't grow on it
mannitol salt agar
selective and differential
proteose peptone, beef extract, d-mannitol, NaCl, agar, phenol red indicator
highly selective
used for isolation of STAPH
osmotolerant
growth of bacillus subtilis on different media
yes on nutrient agar
no on MacConkey
yes on phenylethanol
growth of s. aureus on media
yes on nutrient agar
no on MacConkey agar
yes on phenylethanol
growth of e. coli on media
yes on nutrient agar
yes on MacConkey
no on phenylethanol
minimum temperature
lowest temperature at which growth occurs
optimal temperature
enzyme reactions occur efficiently and reproduction proceeds at a maximal rate
maximum temperature
upper limit at which reproduction is possible
above this temperature protein denaturation, loss of enzyme activity, and cell death occur
psychrophiles
-5C to 20 C
optimum growth is 15 C
mesophiles
20 C to 45 C
optimum growth is 37 C
human pathogens grow optimally at 37 C
psychotrophs represent a special category of mesophiles that can also grow at 0 C, refrigerator temperature
thermophiles
45 C to 60 C
facultative thermophiles will grow at 37 C, but grow best at higher temperatures
obligate thermophiles will only grow at elevated temperatures
temp classification of pseudomonas fluorescens
psychrophile
temp class of e coli
mesophile
temp class of staph aureus
mesophile
temp class of bacillus stereothermophilus
thermophile
temp class of serratia marcescens
mesophile
pigment production
prodigiosin by serratia parcescens is temperature dependent
osmosis
movement of water from an area of higher water concentration to one of lower water concentration
osmotic pressure
pressure exerted by excess water in the cell, pressing the cell membrane against the cell wall
hypotonic
an environment external to the cell with lower solute concentration and higher water concnetration
hypertonic
an environment external to the cell with higher solute concentration and lower water concentration
plasmolysis
results when the cell membrane shrinks from the cell wall and the cell protoplast becomes dehydrated
in hypertonic solutions
non halophilic bacteria
sensitive to the effects of increasing salt concentrations outside the cell
includes coliform bacteria and psuedomonads (e coli and pseudomonas aeruginosa)
halotolerant or osmotolerant bacteria
survive NaCl concentrations of 7.5 to 10 percent
staph aureus
staph aureus as halotolerant
synthesize proline when grown in high salt
makes internal cytoplasm hypertonic to outer environment and water flows in
betaine and choline raise osmotic pressure
MSA to isolate it
grow on skin in high salt concnetration (skin infection risk)
extreme halophiles
require high salt concentrations for survival
halobacterium salinarium
halobacterium salinarium
extreme halophile
gram negative
non spore forming
bacillus
requires salt to stabilize cell wall and enzymes
uses potassium ions to survive, transports them into cells and keeps them in cytoplasm
water enters to prevent dehydration
food preservation
salts and sugar are added to foods to increase osmotic pressure and aid in food preservation
high concentrations of sugar in fruit preserves and drying of foods create hypertonic condtions that inhibit bacterial and fungal growth after processing
pH
measures the concentration of hydrogen ions in a solution
pH scale extends from 0 to 14
neutral is 7
less than 7 acidic
greater than 7 alkaline
influences growth of microorganisms
neutrophiles
most microorganisms grow well in a pH range of 6 to 9 and are termed neutrophiles
fungi can tolerate a wider range of pH than bacteria since they grow well in a pH range of 4 to 9
obligate acidophiles
only grow at the low pH of 2 to 3
when these cells are grown in a neutral pH environment, the cell membrane lyses and the cells die
hydrogen ions are necessary to stabilize the cell membranes of these cells
alkalinophiles
grow at a pH range of 10 to 12
examples of obligate acidophiles
euglena mutabilis
thermoplasma
how does helicobacter pylori neutralize the acidity of the stomach?
metabolism of urea
ulcer bacterium
strong acids and alkalis are
bactericidal
very low nad high pH...
interfere with enzyme activity, denature proteins, and block transport of substances into cells
sorbic and benzoic acids
organic acids used as preservatives in medicines and foods
pH and mouth
formation of dental caries depends on the production of acid by strep and lactobacilli
acid demineralizes tooth enamel and promotes caries formation
pH at tooth surface can be reduced to 5 or less
pH and stomach
HCl in the stomach inhibits many microorganisms like campylobacter that causes enteritis
many enteric pathogens are protected by food particles as they pass through the staomch and are not destroyed by stomach acid
enteric organisms like e. coli can produce intestinal infections in the small and large intestine
pH and human skin
human skin has a pH of 5 due to fatty acids release by sebaceous glands
low pH and dryness of the skin inhibits many microorganisms
osmotolerant bacteria like staphylococcus aureus survive in this pH and are an example of transient flora of the skin
pH and vagina
lactic acid bacteria is commonly found in the vagina, normal flora
maintain the acid pH of the reproductive tract by fermenting gloycogen found in the vaginal mucosa to acids
the normal pH of the vagina is about 3 to 4
acids produced by lactobacilli help suppress uropathogens such as e coli, klebsiella, proteus, and the yeast candida albicans
consequences of antibiotic treatment of the vagina
when lactobacilli are suppressed by antibiotics, the vaginal pH rises, and urinary pathogens can increase in innumber and cause infection
vinegar, acetic acid, douches are sometimes used to restore pH and to treat vaginal infections
Ignaz Semmelweis
established the importance of handwashing, reduced incidence of puerperal sepsis or childbed fever after childbirth
from autopsies to maternity ward
singlemost important thing we can do to keep from getting sick and spreading illness to others
hand washing
where are transient and resident flora found?
on skin, mucous membranes, mouth, pharynx, large intestine, urethra, vagina
transient flora
bacteria commonly found on skin
eliminated by handwashing for 30 seconds or killed by lysozyme in sweat, fatty acids in sebaceous, or low skin pH
staph aureus, g - coliforms, clostridia, aerobic spore forming bacilli in air water and soil
resident flora
more permanent bacteria
not easily removed by handwashing
diphtheroids such as corynebacterium, propionibacterium, s. epidermidis
components of milk
protein, lipids, carbohydrates, minerals, vitamins, pH near neutral
purpose of protein in milk
casein
digested by proteolytic bacteria
purpose of lipids in milk
digested by lipolytic bacteria
purpose of carbs in milk
lactose
fermented by a variety of bacteria
minerals in milk
calcium, phosphorous
vitamins in milk
vitamin D
pH in milk
near neutral, favors the growth of a variety of microorganisms
contamination of raw milk
due to bacteria on the cow udder, utensils used in milking, and dust and dirt exposed during handling, raw milk becomes contaminated by pathogens
neutral pH and nutrients from milk make it a good bacterial growth environment
common genera found in raw mlk
bacillus
streptococcus
lactobacillus
pathogens found in raw milk
m. tuberculosis (TB)
brucella (brucellosis)
s. typhi (typhoid feverE)
coliforms (e. coli)
coxiella burnetii (Q fever)
listeria monocytogenes (listeriosis)
pasteurization
72.5 c for 15 seconds
eliminates most disease causing organisms
thermoduric organisms survive pasteurization
thermoduric organisms
s. lactis and lactobacillus that ferment lactose to lactic acid to make milk sour
some spore formers in Bacillus that digest milk proteins
Raw milk standards
Grade A- can have 100,000 bacteria per mL prior to mixing
after mixing, can have up to 300,000 bacteria per mL
pasteurized milk standards
grade A pasteruzed-
no more than 20,000 bacteria per mL, no more than 10 coliforms per mL
bulk transport has 100 coliforms per mL
standard plate count
determines the number of bacteria in milk and milk products
used to evaluate the number of organisms/mL in good/poor quality milk
milk samples diluted then plated, then incubated and counted
purpose of glass beads in standard plate count
sterile, easy, quick, no flaming, spread cells evenly, every cell. grows into colonies
glycolysis
process of energy release in cells that involves the anaerobic breakdown of glucose to pyruvic acid or lactic acid
two stage pathway leading to ATP formation and pyruvic acid
first stage of glycolysis
glucose + NAD --> diphosphoglyceric acid and NADH
preparation phase
second stage of glycolysis
ATP production phase
pairs of high energy phosphorous atoms removed from sugars and added to ADP = ATP
2 net ATP
remaining is pyruvic acid
fermentation
NADH transfers hydrogen to pyruvic acid = lactic acid
involves redox of organic compounds where there are no added e- acceptors
anaerobic
no e transport phosphorylation
oxidation of NADH to NAD, continue in glycolysis
which bacteria ferment sugars?
enterobacteriaceae
homolactic fermentation
strep and lactobacilli
produce primarily lactic acid from pyruvic acid
heterolactic
strep and lactobacilli
produce lactic acid, ethanol, co2
methyl red test
measures the production of mixed acids by fermentation of glucose
4x as much acid is produced so pH is reduced below 4.4
formic acid is split into hydrogen gas and carbon dioxide gas because of formic hydrogenylase
which bacteria produce mixed acids by pyruvic acid fermentation? (methyl red indication)
enteric bacteria
escherichia, salmonella, proteus, shigella, yersinia
mixed acids produced in methyl red test
lactic acid, acetic acid, succinic acid, formic acid
voges proskauer test
measures the production of the neutral end product acetoin by glucose fermentation
pH drops as pyruvic acid is produced by sugar glycolysis, then rises as there are more neutral products
bacteria that ferment pyruvic acid to neutral end products (acetoin and butanediol in V P test)
Enterobacter
serratia, klebsiella
nonfermenters
aerobic, non spore forming bacilli
non saccharolytic
do not use carbs or metabolize carbs in oxidizing fashion
non fermenter examples
alcaligenes faecalis (non saccharolytic)
pseudomonas aeruginosa (sugar in oxidative fashion)
pseudomonas aeruginosa
changes glucose to pyruvic acid by a pathway that doesn't use the 3 carbon compound
weak acids produced that don't change indicators
pyruvic acid oxidized in krebs and e transport = CO2 and water
phenol red test
yellow color in tube means acid production
yellow color and gas = acid and gas production
red color in tube = no fermentation
chemical control
control increase in numbers of microbes
kill microorganisms or stop their growth
bacteriostatic agents
stop multiplication of bacteria
no killing
bactericidal agents
kill bacteria
disinfectants
used to kill on nonliving surfaces
kill microorganisms present in spills
antiseptics
used on body
less toxic than disinfectants, inhibotry to microorganisms
like neosporin
categories of chemical antimicrobials
phenols
halogens
alcohols
quats
phenols
phenol, cresols, orthophenylphenol, hexachlorophene, lysol
denature proteins, break down cell membrane, nutrients leak out, cell dies
halogens
potent oxidizing agents
povidone iodine and chlorine
povidone iodine
kill microorganisms on skin before surgery
iodine combines with tyrosine to denature proteins
chlorine
drinking water, swimming pools
combines with water = hypochlorous acid (strong oxidizing agent)
alcohols
dissolve lipids in cell membranes and denature proteins
absolute alcohol not effective- presence of water required
70-80%
quats
hydrophobic chains with charged group
positive charged quats = cationic (more effective against bacteria and gram positive)
negatively charged quats = anionic
cationic combines with negative phospholipids in membrane and break it down
examples of quats
alkylmethylbenzylammonium chloride, benzalkonium chloride, cetylpyridinium chloride (mouthwash)
what is a dangerous antibacterial in the home?
triclosan- endocrine disruptor, contamination of enviironment, carcinogen possibility, pregnancy problems
is the zone of inhibition size an indicator of effectiveness of an antimicrogial?
no, not directly because some chemicals diffuse slowly into agar
does not distinguish between bactericidal and bacteriostatic agents
the magnification of the oil immersion objective is
100 x
what is the lower limit of resolution with the light microscope?
.2 um
in microbiology, aerosols are
droplet infections and a way in which airborne infections are spread
inanimate environmental surfaces include
tables and floors
in order to sterilize heat sensitive liquid media, one should
run the liquid through a filter
nutrient broth contains
peptone and beef extract
microbial growth in nutrient broth is detected by
cloudiness in the broth
a pure culture is defined as having
progeny from one isolated cell
the streak plate technique will produce pure colonies because it results in
special dilution
safranin stains cells
redish pink
which of the following is used for a simple stain of a bacterial cell?
a basic dye
the mordant used in a gram stain is
iodine
which of the following microorganisms is a gram positive rod?
bacillus subtilis
what dye does mycolic acid typically bind?
carbolfuchsin with heat
which of the following genera is acid-fast?
mycobacterium
two of the chemicals resposible for endospore resistance are
calcium and dipicolinic acid
a false statement concerning endospores is
endospore formation is a method of cell division
a capsule is composed of
polysaccharides
the blank is used for the serological identification of specific encapsulated bacteria
quellung test
random back and forth jiggling is called
brownian movement
a cluster of flagella on each end of the bacterium is defined as
amphotrichous arrangement
the gram stain procedure follows which sequence?
crystal violet, iodine, acetone, safranin
bacteria in the genus mycobacterium are best stained using which procedure?
acid fast stain
a packet of 8 to 16 cells is described as
not tetrad, strep, or staph so idk?
the rate of cell growth for a pschrophile is greatest at
the optimal temperature
human pathogens grow optimally at what temperature?
37 C
as a microorganism grows in a liquid culture, the turbidity of the broth should
increase
plasmolysis is due to
dehydration and cells in a hypertonic solution
proline and choline are valuable to staphylococci because they
accumulate and raise osmotic pressure
microbes hep promote dental caries by producing
acids
microorganisms that are not permanent on the skin are termed as
transient flora
generally, a brief thirty second period of scrubbing removes transient organisms from the skin
true
which of the following is not a thermoduric organism?
escherichia
strep and bacillus are thermoduric
grade A pasteruzied milk should not contain more than
20,00 0 organisms
homolactic fermentation produces
lactic acid
the methyl red test measures
production of mixed acids by fermentation of glucose
which of the following is not a class of antimicrobial agents?
salts
which of the following acts as a strong oxidizing agent?
halogens
an antimicrobial substance produced by living organisms that either kills or inhibits other microbes is
an antibiotic
a risk associated with aminoglycoside antibiotics is
toxicity
what is the wavelength of light most strongly absorbbed by DNA?
260 nm
the most common pyrimidine dimer is the
thymine dimerp
hotoreactivation is prevented by
covering the irradiated plates with aluminum foil
hemolytic reactions can be observed using
agar containing blood
which of the following skin infections are caused by staph aureus
boils and impetigo
staph aureus
coagulase positive, ferments mannitol, and produces colonies with a yellow halo on MSA plates
the dextran covering surrounding bacteria on the teeth is termed
glycocalyx
the snyder test measures acid production by oral blank that produce dental caries
lactobacilli
About this deck
By: Rachel Farnsworth
Created: 2011-12-03
Size: 303 flashcards
Views: 29
Created: 2011-12-03
Size: 303 flashcards
Views: 29
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj