-
What are biosafety levels
- BSL 1 = Not known to consistently cause disease in healthy individuals.
- BSL 2 = Associated with human disease. Acquired by percutaneous injury, ingestion, exposure to mucous membrane.
- BSL 3 = Disease may have serious or lethal consequences. Potential for aerosol transmission.
- BSL 4 = High risk of life threatening disease. Aerosol-transmitted infection.
-
total magnification
Ocular x objective
-
numerical aperture
ability of a lens to capture light from a specimen to make an image
-
ocular lens
- is the eye piece (ocular)
- is 10x
-
objective lens
- is the milk tits of microscope
- 4X
- 10X
- 100X
- 1000X
- To figure total magnification, multiply the 10X of ocular lens X pwr of objective lens
-
resolution
refers to the amount of detail you can see in an image
-
limit of resolution
minimum distance btwn 2 objects such that the two objects still appear separate and distinct
-
equation to figure limit of resolution
where the top is wavelength
-
condenser lens
- lens below the objective lens
- concentrates the light and makes illumination of specimen more uniform
-
Alkaline stain (dye) vs acid stain
- Alkaline stain has positive charge to it
- Acid stain has neg charge
*understand most bacteria are neg charge, so usually use alkaline stain
-
What chemicals have positive charge (is an alkaline dye)
- Crystal violent
- Saframine
- malakye green
Some cells stain purple, others will stain pink
-
simple stain vs differential stain
- simple stain simply tells you general shape and size
- differential stain lets you differentiate btwn bacteria
-
order of chemicals used in gram stain
- crystal violet ~
- iodine ~ mordant, fixes stain into something
- alcohol ~ decolorizer, washes out purple color in gram neg.
- safranine ~ counter stain, gram neg
-
disinfectant vs. antiseptic
- disinfectant kills organisms on objects
- antiseptic less harsh, kills organisms on living tissue
-
Antimicrobials
- Chemical that cures disease
- selective toxicity:
- 2 types:
- synthetic, made by chemist (antimicrobials)
- antibiotics
-
Kirby-bauer test
- test on big plate
- test which antibiotic a microbe is most effected by
-
in Kirby-bauer test, what is zone of inhibition
- measure of susceptibility of a drug to an organism
- you'll check chart to read how suseptible
-
starch hydrolysis test
- medium contains starch
- inoculate germ on plate, allow to grow
- Next day you flood plate with iodine
- wherever there is starch, it turns black
- where it's white, microbe produces an enzyme that eats starch
-
carbohydrate fermentation tests in tubes
- if organism ferments carbohydrate, it produces acid
- yellow is positive test
- red to pink is negative test
-
urease test in tube
- some organisms can produce an enzyme that degrades urea
- if it's positive, it will produce pink/purple color
- no pink = urease neg
-
catalase test
- commonly done on slip, you add hydrogen peroxide
- if it bubbles, catalase pos
- no bubbles, catalase neg
-
oxidase test
- uses little square thing w four windows
- if oxidase positive, turns purple on paper
-
Nitrate reduction test
- done in tubes
- if red, positive
- if no red, neg
-
plated media used in class
- Tryptic soy agar (TSA)
- Blood agar (Bap)
- Eosin Methylene blue agar (EMB)
- MacConkey agar (MAC)
- Starch hydrolysis agar
- Bile Esculin agar (BEA)
-
Differential vs selective
- Selective: contains something that allows growth of some bacteria, but inhibits others
- Differential: allow differentiation of organisms
-
EMB and MAC
- Both are selective and differential
- allows growth of gram neg only
- differentiates lactose vs non-lactose fermenters
- on EMB, lactose fermenters turn pink or dark purple
- on MAC, lactose fermenters turn pink or red
-
gram pos bacillus
- bacillus species OR clostridium species
- BOTH PRODUCE SPORES
-
Bacillus species
- gram pos
- aerobic
- cat +
- starch +
- found in soil
-
Clostridium species
- gram pos bacillus
- anaerobic
- cat -
- starch -
- found in soil
-
gram pos cocci ex:
- Staph aureus
- staph epidermidis
- strep pyogenes
- --- on TSA, these are white
- enter faecalis
- -- on TSA, these are yellow
-
A yellow organism growing on TSA plate...
- is micrococcis ludeis
- is gram pos coccus
-
tests used on gram pos cocci
- MSA, BAP, BEA
- catalase test
- bacitracin sensitivity test
-
Beta, alpha and gamma hemolysis
- On BAP agar
- Beta hemolytic completely lyse RBC. if inhibited by bacitracin, is S. pyogenes
- Alpha hemolytic is partial, S. pneumonia
- Gamma is none. E. Faecalis
-
What grows on MSA
- STAPH!! only staph
- If yellow colonies, produces manital & is staph aureus
- salt inhibits growth of anything except staph
- if orgainism is pink, is another staph.
-
BEA
- sick greenish/yellowish color
- when something turns black on this medium, ID as Enterococcus faecalis
-
Gram neg bacilli
- Enterobacteriaceae bacilli (enteric)
- Pseudomonas aeruginosa (non enteric)
-
Enterobacteriaceae
- Gram neg bacilli
- oxidase neg
- ferment glucose
- nitrate reductase pos
-
Pseudomonas aeruginosa
- gram neg bacillus
- oxidase pos
- does not ferment glucose
- reduces nitrate to nitrogen gas
|
|
