Week 3 Flashcards
Chapter 2,3 and 26
Epidemiology
the study of how a specific agent survives and spreads through a community
Disease Transmission
the actual way the infectious agent spreads
Examples of Disease Transmission
- handshake
- kiss
- cough
- biological vectors (ex: mosquito)
Portal of Entry
Entrance-way through which a specific microbe is able to invade a host
Examples of Portals of Entry
- Gastrointestinal tract
- Respiratory tract
- Conjunctiva
- Skin
- Urogenital Tract (STD)
- Pregnancy and birth
Reservoir of Infection
Any object, living or non-living, that allows a microbe to grow, reproduce, and maintain its ability to remain infective
ex: makeup, nose-drops, eye-drops
Fomites
a non-living object capable of allowing a microbe to survive but not reproduce
- an inanimate object that can serve as a vehicle for the spread of disease
- proper and consistent hand washing controls fomite transmission
Examples of Fomites
- test tubes
- books
- pens
- cell phones
- stethoscope
- syringes
- call buttons
- bed linens
- toilet seats
- door knobs
- diner plate
- forks, spoons, knives
Hand Washing
the single most important method of controlling microbes in a clinical setting
-every person alive is a host to about 100 trillion bacterial cells
>outnumber human cells
Isolation Streak Plate
Utilized to separate individual bacteria from mixtures
- most widely used method of obtaining a pure culture
- samples from patients and the environment are mixtures of different bacteria
Goal of The Isolation Streak Plate
Goal of a streak plate is to thin out the number of bacteria on a plate to get isolated colonies
- all members of the colony are genetically identical and arose from a single bacterial cell
- isolated colonies are needed for all tests and procedures
Pure Cultures are needed to:
- carry out biochemical testing for identification purposes
- determine antibiotic sensitivity
- determining nutritional and growth requirements
- study the organism and the disease it causes
- develop vaccines
Spread-plate method
- sample is pipetted onto surface of agar plate
- sample is spread evenly over surface of agar using sterile glass spreader
- Incubation
- Typical spread-plate results (surface colonies)
Pour-plate method
- sample is pipetted into sterile plate
- sterile medium is added and mixed well with inoculum
- Incubation
- Typical pour-plate results (subsurface colonies, surface colonies)
Robert Koch
He and his team developed many of the techniques used to isolate bacteria in pure cultures
Agar
substance derived from seaweed
- melts at 100 Degrees Celsius
- remains liquid above 45 Degrees Celsius
- solidifies completely at 40 Degrees Celsius
-Agar provides a solid surface to grow bacteria–> isolated colonies
Colony
clump of bacteria growing on a solid surface
- every cell in the colony arose from a single cell
- every cell in the colony is genetically identical
Media
-Synthetic growth media is used in laboratories to culture (grow) bacteria
Media must provide the nutrients an organism needs to grow:
-a nitrogen source (peptones or amino acids)
-Carbohydrates
-minerals (sulfur, phosphorous)
-buffers to maintain pH
-vitamins may also be added
Forms of Media
- Agar Plate
- Agar Deep Tube
- Broth
- Agar Slant
Tryptic Soy Media
Contains: -Dextrose (carbohydrate) -Tryptone (milk casein) -Soybean Protein -Salt Media is available in both broth and agar forms
Making Media
- Powdered media dissolved in distilled water
- Media is dispensed into tubes or bottles
- Autoclave to sterilize
Making Media: Autoclave
Used to Sterilize
- Temperature: 121 Degrees Celsius
- 15 lbs of pressure per square inch
- 15 minutes- kills vegetative bacteria, fungi, viruses and endospores (spores)
Tools + Equipment: Incubator
holds a constant temperature, used to grow bacterial cultures
Tools + Equipment: Incinerator
device used to sterilize inoculating tools (needle, loop)
