LAB 10 Flashcards
For Rapid’E coli agar what color does it turn if GAL Galactosidase is present?
Blue-green
For Rapid’E coli agar what color does it turn if GLUC Glucuronidase is present?
Pink
*ecoli has both = purple
Eosin Methylene blue turns what color if coliforms are present?
Pink - dark purple
Eosin Methylene blue turns what color if rapid lactose fermenters are present?
Metallic green colonies
Eosin methylene blue turns what color if no coliforms are present?
Orange-red
MacConkey agar turns what color if coliforms are present?
Pink
McConkey agar turns what color if coliforms are not present?
Tan
Hektoen Enteric Agar turns what color if any of the 3 sugars were fermented?
Yellow-pinkish-orange
Hektoen Enteric Agar turns what color if no coliforms are present?
Blue-green
Hektoen Enteric Agar turns what color if sulfur reduction occurred?
Black
S. aureus may be normal flora of?
Human nares and skin
E. Faecalis may be found in?
Gastrointestinal tract
Pyogenic causing abscesses and can invade tissues to cause systematic diseases like acute endocarditis, necrolytic pneumonia and toxic shock syndrome
Staphylococcus aureus
It May be normal flora in the vaginal tract and is associated with urinary tract infections
Staphylococcus saprophyticus
Common member of skin flora but it may be associated with nosocomial infections of the blood
Staphylococcus epidermidis
Species that can cause bloodstream infections and be resistant to antibiotics such as vancomycin and resistant enterococcus
Enterococcus
What are 2 metabolic products of cellular respiration
Reactive oxygen species and superoxide radicals
Organisms like staphylococcus that live in oxygen-rich environments must be able to break down?
Products of cellular respiration
Hydrogen peroxide h2o2 is an example of
reactive oxygen species
The enzyme that breaks down hydrogen peroxide into water and oxygen
Catalase
Staphyloccus species are _____positive
Catalase
Performed by placing a loopful of bacteria into a drop of hydrogen peroxide and watching for the formation of oxygen bubbles
Catalase test
In the catalase test, if we see bubbles, it means? No bubbles?
Bubbles = species is staphyloccus
no bubbles = not staphyloccus - catalse negative
After a unknown bacterium is presumed Staphylococcus, what other methods can determine the species?
Mannitol salt
Hemolysin
Coagulase
Mannitol Salt contains
Sugar mannitol and 7.5% salt
What 2 species of staphylococcus can ferment mannitol (sugar), and what color will it turn?
S. Aureus & S. saprophyticus - YELLOW
What species of staphylococcus cannot ferment mannitol (sugar), and what color will it turn?
S. epidermidis - RED
What does Hemolysin do?
Breaks down red blood cells similar to a-toxin of black widow. Causes local necrosis
If a species of staph is positive for hemolysin what will it show? Negative? and which species
S. Aureus positive - beta (complete) hemolysis
S. epidermidis & S saprophyticus negative - gamma hemolysis
Study of diseases in a population
*how, when, where, what, who are involved in source of spread
Epidemiology
Occurrence of a disease in a population
Outbreak
Point source
everyone affected got it from a common source ie. food poisoning
Propagated
Diseases spread between people or animals. The number of cases builds over time
Case index or patient 0
A person who was originally infected
Diseases that occur in a particular community at higher than expected rates
Epidemic
an epidemic that spreads to more than 1 continent, infecting a large number of susceptible individuals
Pandemic
A disease that is spread between people. This causes a propagated outbreak
Communicable
a disease that is spread by vector (lymes disease)
Noncommunicable
a disease spread from an animal to a person (rabies)
Zoonosis
non-specific immunity, present at birth, no memory
Innate
developed as a result of exposure to a specific organism
Acquired
Resistance of a group to the invasion or spread of an infectious organism
Herd
Occur naturally in some bacteria to protect them from viral infections
Restriction enzymes
What do restriction enzymes do
recognize specific nucleotide sequences within DNA strands, bind to recognized sites, and cut DNA between those based, creating different-sized fragments
When multiple restriction enzymes are used a unique pattern of DNA fragments called
DNA fingerprint - which can be used to identify an unknown microorganism
To determine the number and size of DNA fragments, they must be
Separated by agarose gel electrophoresis
a porous material that provides a semi-solid medium for DNA to move through
agarose gel
Agarose gel also contains a chemical compound called? and does?
GelGreen - binds to DNA & will fluoresce under UV radiation
Gram-positive cocci include
Staphylococcus aureus & Enterococcus gecalis
Staphylococcus aureus causes
abscesses and has the ability to invade cause systemic diseases such as acute endocarditis, necrolytic pneumonia, and toxic shock syndrome
Ex. MRSA
Enterococcus fecalis is a common cause of
bloodstream infections as well as being resistant to antibiotics
ex. VRE
Staphlyococcus are
gram ( ) Cocci
Catalase ——-
how will they show on the catalase test?
Gram POSITIVE cocci and catalase positive so they will bubble in
on the catalase test they will bubble showing they have the enzyme catalase to break down toxic oxygen materials
What is the enzyme used by aerobic and facultative bacteria that breaks down toxic oxygen material
Catalase
*anaerobic and microaerophilic bacteria do not have this and cannot live in oxygen
S. Aureus
Mannitol salt?
Hemolysin?
Coagulase?
Halotolerant?
S. Aureus
Mannitol salt - POSITIVE - YELLOW
Hemolysin - POSITIVE - Complete clearing B helolysis
Coagulase - POSITIVE- clumps/clot
Halotolerant - POSITIVE
S. saprophyticus
Mannitol salt?
Hemolysin?
Coagulase?
Halotolerant?
S. saprophyticus
Mannitol salt - POSITIVE - YELLOW
Hemolysin - NEGATIVE
Coagulase - NEGATIVE
Halotolerant - POSITIVE
S. Epidermidis
Mannitol salt ?
Hemolysin?
Coagulase?
Halotolerant?
Mannitol salt - NEGATIVE - RED
Hemolysin - NEGATIVE - gamma
Coagulase - NEGATIVE
Halotolerant - POSITIVE
The catalase tests help determine between what 2 bacteria?
Positive - staphylococci
Negative - Enterococcus
If Staphylococcus aureus is identified, what other important test should be done?
Coagulase
When scientists have a good idea of how much disease is occurring for a geographical area
epidemic rate of disease
Propogated epidemics are
infections that spread from one person to another because the disease is communicable
Define and differentiate point source and propagated epidemic?
Point source -persons are exposed over a brief time to the same source, such as a single meal or an event.
Propagated epidemic - when the infection spreads from one person to another, e.g. through the air, via a vector, via contaminated food or water, or during unprotected sexual intercourse.
What is a microorganism that causes a pandemic?
virus
DNA generally exists as
2 long strands of complementary nucleotides
IN eukaryotes how does DNA appear?
How does it appear in Viruses?
Eukaryotes - double helix circular form
Viruses - single or double, circular or linear
DNA can be cut with enzymes called?
and are useful for?
Restriction enzymes
to protect against a viral infection by destroying the DNA
What is agarose gel electrophoresis used for
to separate negatively charged DNA fragments using an electric current
