Microbiology Lab Flashcards

Terms Definitions
Define pyogenic.
Disease causing organisms.
What bacteria causes tuberculosis?
Mycobacterium tuberculosis
antigen-antibodies complexes form and precipitate. identity: curved line;non-identity: crossed lines;partial-identity: curved line with spur
cold-loving organisms (0-20 deg C)
List one disease associated with Staphylococcus aureus.
Why Standardization?
aviod variation; evaluate one varible
gram (+), catalase negative, chains, skin normal flora, divided into group A,B,C,D, Pneumococcus, or viridans
Classification by Arrangement: strepto
chains of cells
used in processing milk products, fruit juices, beer and wine.  Kills vegetative pathogens and some microbes involved in food spoilage.
What does ELISA short for?
Enzyme-Linked Immunosorbent Assay
Salmonella are related to __________ which are normally found in the large intestine.
E. coli
Differential media
contains an indicator to distinguish between different types of bacteria
the study of the causes, occurrence, transmission, distrubution, and prevention of disease
kills bacteria best is the alcohol pad
aseptic technique
practices used by microbiologists to exclude all organisms from contaminating media or contacting living tissues.
Dry heat methods
killing microorganisms by denaturing proteins and oxidation (burning) of vital structural and metabolic chemicals.
What were the unknown sputum observations and results?
Blue and negative.
What are the three major groups that make up the "Pyogenic Cocci"?
Eosin Methylene Blue Agar Plate
selective -- Gram-negative (growth)differential -- lactose fermentation (gold sheen-fermenter/pink-weak fermenter)
Salmonella and Shigella Agar Plate
selective -- Gram-negative (growth)differential -- lactose fermentation (pink) and sulfur reduction (black colonies)
pure culture
only that one specific species growing on a culture medium. Rare in nature, usually occurring during extreme environmental conditions.
Beta hemolysis
the complete destruction of red blood cells on a blood agar plate. Appears as a clear zone around colonies on a blood agar plate.
Direct Flaming
Dry heat method.  Passing tube or loop through flame
What is a Mycobaterium species that is part of the normal flora?
Mycobacterium smegmatis
Give three examples of normal residents in the skin.
Staphylococci (mainly S. epidermidis),
streptococci (α-hemolytic, nonhemolytic),
yeasts, and fungi.
prevalence rate
total # of cases/# of people in Pop.
negative (background) stain
a staining procedure that results in colorless (clear, unstained) bacteria against a dark stained background.
Working Distance
The distance between the slide and the objective lens when the specimen is in focus.
Where does Moraxella catarrhalis inhabit? What does this strain frequently cause?
Inhabits the mucosa.Causative agent of a lower respiratory disease.
Name one example of antibiotics.
Streptomycin = interferes with protein synthesis.
Standard Plate Count of Milk
most reliable to determine sanitary quality of milk, High numbers means there is a higher liklihood of disease transmission, but does not means pathogens are present
simple vs. compound microscope
- 1 lense (magnifying glass)-2 lenses or more
Transient Flora
Organisms which are only in or on the body for a short time and do not become established onthe body.  Do not cause diseases.
What is the positive control and why is it used?
Mycobacterium smegmatis
To confirm acid fast procedure and positive results
Normal or Resident Flora/Microbiota
Organisms which colonize the body in a symbiotic relationship that is commensalistic or mutalistic (Mutualism: a mutually beneficial relationship, both organisms are benefited.  Commensalism: one organism is benefited and the other is neither benefited nor harmed.)
What is the role of Mycobacterium smegmatis?
A combination of exfoliated (shed) epithelial cells, transudated skin oils, and moisture, and can accumulate under the foreskin of males and within the vulva of females. It has a characteristic strong odor.  Mycobacterium smegmatis is the characteristic bacterium involved in smegma production, and is generally thought to form smegma from epidermal secretions.
What is another mode of transmission?
Any oral direct contact with infected saliva (straws, pop bottle)
What is the role/purpose of substrate reagent in the ELISA assay?
The substrate reagent contains H2O2 and aminosalicylate. The horseradish peroxidase in the secondary antibody would react with this and indicate the oxidation of salicylate. If it salicylate is oxidized, you'd see brown, which also indicates positive for antibody.
Why necessary to have pure culture
-needed for Germ Theory and Koch's Postulates-identify unknown bacteria you need a pure culture-needed for identifying specific spoilage and pathogenic microorganisms-Pasteur needed to explain fermentation- need to test water for quality and safety-needed to determine the quality and safety of food and milk
What is another name for Chronic Fatigue Syndrome caused by EBV?
Yuppy or Generation X disease because of the major symptom of fatigue
different types of lenses in a compound light microscope
- ocular lens 10X (used on all!!)1)scanning: 4X --> total magnification 40X2)low power- 10X --> total 100X3)high power- 40X---> total 400X4) oil immersion- 100X --> total 1000X
What is a unique characteristic of mycobateria that causes testing problems?
It grows very slowly, 4-6 weeks to grow visible colonies.
What is the role/purpose of horseradish peroxidase in the ELISA assay?
This was used as an enzyme that is linked to the anti-IgG antibodies.
The enzyme would bind to a substrate, and if the anti-IgG antibody was present, you'd see a brown precipitate. 
If no anti-IgG antibody is present, then the substrate would have nothing to bind to, and you'd get no color.
Generally describe the ELISA test procdure?
Ab is produced in IR to Ag (drawn in blood serum)
Ag is added to well and coats.
Patients Ab is added and binds to Ag (not visible)
Secondary Ab with bound enzyme is added to well and is specific to EBV Ab (will not bind to Ag if EBV is not present)
PBS is a buffer solution used to wash/rinse unbound EBV Ab and Secondary Ab out of well.
Substrate with dye binds to Enzyme on Secondary Ab only if present.
What is the role/purpose of IgG antibody in the ELISA assay?
IgG antibody is there to act as a positive control.
Is the test used in lab a direct or an indirect ELISA test?  How did you know?
Indirect because we were looking to detect the presence of HIV antibodies.
like acidic pH
Like alkaline (high pH)
Endo Agar
selective -- Gram-negative (growth)differential -- lactose fermentation (gold sheen-fermenter/pink-weak fermenter)
Medically important: staph aureus, only one YELLOW on MSA plateMSA = differential and selective mediaStaph found in nose, skin and hairG+ and cocci (purple and berry shaped)non spore formers
What Mycobacterium species causes leprosy?
Mycobacterium leprae
an enzyme that degrades the peptidoglycan layer in cell walls causing cell lyses; 1st line of defense -- non-specific immune mechanism
MacConkey Agar Plate
selective -- Gram-negative (growth)differential -- lactose fermentation (pink)
the fine, microscopic, details of organisms, tissues and cells.
any inanimate object or substance capable of carrying infectious organisms (such as germs or parasites)
Steam heat under pressure.  Most reliable way of sterilization.  Standard pressure is 15 PSI, 121 deg C for 15 mins.  
Which group of organisms form opaque colonies that have a glossy appearance, are yellow to white in color, and are usually facultatively anaerobic?
Hektoen Enteric Agar Plate
selective -- Gram-negative (growth)differential -- lactose fermentation (yellow) and sulfur reduction (black colonies)
FC Agar
Sele: gram (-); Diffe: gram(-); positive: blue colonies.
oxidation of nitrogen in the ammonium ion to produce nitrite; nitrite is then oxidied into nitrate.
alpha hemolysis
incomplete destruction of red blood cells on a blood agar plate. Appears as brownish-green zone around a colony on a blood agar plate.
selective media
a microbiological growth media that contains chemicals that prevent the growth of unwanted bacteria, but allows for the growth of the wanted species of bacteria.
ex. EthanolUsed to lose color of primary stain and before counter stain
Classification by Arrangement: tetrad
groups of four cells
How can streptococci be identified?
Charastic antigens
Hemolytic reactions in blood agar.
What is another name for mononucleosis?
The kissing disease
Which group of microbes are the most common Gram - cocci of medical importance?
In the direct test what would you obtain from the patient to perform the test?
Mannitol Salt Agar Plate
selective -- micrococcus and staphylococcus (salt tolerance-growth)differential -- mannitol fermentation (yellow)
streak plate method
physically spreading out cells over the surface of solid media far enough so that individual cells can grow into pure colonies.
Classification by Arrangement: staphylo
grape like clusters of cells
Chromatic Abberations
Rainbows and halos that are seen around microscopic specimen when white like is used.
Give one example of synthetic drugs.
Sulfadiazine (sulfonamide) = Bacteriostatic
McFarland Standard
a way to determine cell density based on turbidity
Direct Agglutination
detcts O and H antigens of enteric bacilli;positive: clumping, for Shigella or Salmonella antiserum
counter stain
Used to stain other cells that were not colored and accepted by primary stainEx. safranin
What is the virus that causes mononucleosis?
Epstein Barr virus (EBV)
Give one example of a yeast species that can reside without harming and inside the human body but can eventually cause disease in individuals with lower defenses or those individuals on some kind of antibiotic? What is the general name given to these yeas
Candida albicansOpportunist pathogens
Drying Ovens
circulate hot air, 171 degrees C for 1 hour, or 160 degrees C for 2 hours.  Good for glass, metal, oil and powders.  Some materials, like paper and plastic cannot be sterilized this way without being destroyed.  
Resolution or Resolving Power
the shortest distance two objects can be apart and still be seen as separate (modern microscopes can distinguish between objects that are 0.2 micrometers apart). 
What is the lower respiratory tract?
Larynx, trachea, broncial tubes, and alveoli.
List the five characteristics, of the organisms that cause microbial infections, that provide a profile which is used by the medical microbiologist for preliminary identification?
SizeShape (rods or spheres)Gram Staining Reaction of individual cellsGrowth requirementsColony morphology
What are some normal flora of the RT?
Staphylococcus (Most common, causes sore throat - acute pharyngitis), Steptococcus, Neisseria, and Haemophilis.
These MO compete with pathogens and are considered antogonists.
What does mononucleosis occur in young people in the US and the rest of the world at a younger age?
Poor sanitation and inadequate hygiene leads to younger peoples infections
Younger people have immature IS, specifically the TC (cytotoxic) cells, that cannot cause severe tissue damage typical of mono symptoms.
Compare and contrast RID and Ouchterlony.
RID and Oucherlony are similar because they both use zones of equivalence and the use of precipitants.
RID uses a plate of agarose + antibodies with the use of wells, and the diffusion of antigen. The precipitin rings show zone of equivalence.  RID is a quantitative method that can be used to determine unknown antibody or antigen concentrations.
Ouchterlony uses test tubes where visible zone of equivalence is seen as precipitate in solution. It is a qualitative method to indicate presence of antigen or antibody. 
What is used to test for nitrate production, and what happens?
Trommsdorf's reagent, Sulfuric acid, Diphenylamine reagent; blue-black color change.
What is the negative control and what is it used for?
Bacillus cereus
A known acid fast negative MO, no myolic acid
Confirms acid fast procedure and negative results
What do the circular precipitin rings represent?
The rings represent the reaction of soluble antigen with the antibodies as the antigen diffuses away from the well into the agarose.
What was the procedure for RT bacteria isolation and identification?
Swab throat, streak for isolation of blood agar plate (BAP).
Incubate 18-24 hrs at 37 C
Select isolated different colonies, observe characteristics and hemolytic reaction.
Perform catalase test and alternative catalase test.
Gram stain and record observations.
Why is it called the kissing disease?
It is believed that kissing is the mode of transmission.
Why is acid fact staining test a unique test?
It is confirmatory and only a strong indicator. Since colonies are needed for confirmation testing acid fast staining is used as a quick diagnostic tool. Acid fast results with symptoms are sufficient for diagnosis.
It is also a differential staining method test.
Why do the ring sizes change until equilibrium is reached?
The antigen diffuses out of the well until it there is a zone of equivalence between antigens and antibodies. This is where the antigen and antibody ratio is roughly equal in concentration.
What is a quick test that can be used to differentiate between staphylococcus and streptococcus species?
Catalase Test (Lab 14 Gram positive coccus flow chart)
/ 94

Leave a Comment ({[ getComments().length ]})

Comments ({[ getComments().length ]})


{[ comment.comment ]}

View All {[ getComments().length ]} Comments
Ask a homework question - tutors are online