Exam 4 Flashcards
Where is the light source diaphragm on the microscope
On the bottom, where light comes from
Where is the condenser diaphragm on a microscope
Under the stage
Where is the reostat on a microscope
It’s below the power button on the right
describe an agar plate
good for surface area. pure cultures
what are agar slants used for
storing cultures
what are agar deep’s good for?
showing if the organism is motile
What are CFU’s?
Colony forming units
in a standard plate count, what are you reading?
the colony forming units (CFU’s)
Is Mannitol salts selective, differential, or both?
both
If there is growth in Mannitol salts, what does that mean the organism can survive in?
in salt, (its a halodore)
when the pH goes down in Mannitol salts, what color will it turn?
yellow
Why would Mannitol salts turn yellow?
The mannitol fermented
Is MaConkey agar selective, differential, or both?
both
If bacteria grows in MaConkey agar, is it gram (+) or (-)
(-)
What does the MaConkey agar plate test for?
If lactose fermentation occurs
What color will the MaConkey agar turn if it ferments?
red/pink
what does the starch hydrolysis test test for?
if the organism can eat starch
what does the starch hydrolysis test use?
starch + iodine
if the starch hydrolysis plate clears up and has no color, what does that mean?
the bacteria CAN hydrolyze (eat starch)
is the starch hydrolysis plate differential, selective, or both?
differential
what does an oxidase test look for?
cytochrome C
what color will show is cytochrome C is present in the oxidase test? meaning it is oxidase positive
Blue
in a catalase test, what do you add?
hydrogen peroxide
is bubbles result in the catalase test, what does that mean?
it is catalase positive
the oxidase and catalase tests are both what kind of tests?
complex
mannitol salts test is selective for what
halodures (KEEP STUDYING!!!!)
mannitol salts test is differential for what?
mannitol fermentation
macConkey test is selective for what?
gram (-) growth
macConkey test is differential for what?
lactose fermentation
What test is tested on a blood plate?
hemolysis
if the blood agar turns green, what does that tell you? (2 things)
its Alpha (a) and it is incomplete hemolysis
if the blood agar turns clear, what does that tell you? (2 things)
complete lysis occured in the red cells of media, its Beta (b)
If the blood agar has no change, what does that tell you?
it’s gamma, no hemolysis
what do coloforms look like when they grow?
metallic green
When measuring a zone of inhibition, how is it measured?
in milimeters
do you want susceptibility in antibiotics?
yes
does alcohol kill spores?
no
what do gram stains the properties of?
the cell wall
what are the steps to a heat fix? (7 steps)
1) prepare the smear (loopful of water on slide, place bacteria and smear, let dry)
2) heat fix (over bunson burner x 3)
3) crystal violet (1 min)
4) Iodine (1 min)
5) alcohol (
what does heat fixing do to the bacteria? (3)
1) kills bacteria
2) adheres bacteria to slide
3) denatures proteins in membrane, making bacteria porous so state can penetrate
is gram positive or negative stained purple?
positive
what is epidemiology the study of?
where and when diseases occur and how they’re transmitted within populations
define incidence
the # of new cases of a disease in a given area or population during a given period of time
define prevalence
amount over time
define endemic
a natural occurrence in the area
define sporadic
occurring at irregular intervals
define epidemic
when a disease occurs more often than normal for an area
how far (over land) is an epidemic before it becomes a pandemic?
epidemics refer to 1 continent, not country
what is a pandemic
disease that spreads over more than 1 continent
what are 2 types of nosocomial infections?
exogenous
endogenous
latrogenic
what is an exogenous infection?
caused by pathogens acquired from healthcare environment
what is an endogenous infection?
they arise from normal microbiota in patient and become pathogenic because of factors in the health care setting
what are latrogenic infections
a direct result from a medical procedure. (use of catheters, surgery)
What is LD
lethal dose
what is ID
infectious dose
what are 3 contact transmission examples in infectious disease
direct, indirect, droplet
examples of direct transmission
handshaking, kissing, sexual intercourse