Intro to Microbio Flashcards
(43 cards)
What decreased the death rate in the 20th century?
Implementation of public health departments - most people were getting sick from people throwing their garbage on the streets and allowing animals to decompose on the streets.
So public sanitation and vaccines.
What are the relative size of the different infectious agents?
- virus is the smallest and simplest, non-living infections
- bacteria are the smaller independently living cells
- virus
Which genus of bacteria is predominately food in various location of the body?
skin - propionibacteria
mouth - lots of streptococci
oropharynx - neisseria
stomach and small bowl = helicobacter pylori
colon - bacterioides
nose - staphylococcus
nasopharynx - pneumococci
vagina (during childbirth years) - lactobacillus
vagina (prepub and post menopause) - c. albicans and diphtheroids
What’s symbiotic?
benefits the host - like gut bacteria that participate in digestion
What are commensals?
neutral relationship to the host (oral streptococci)
What is parasitic?
harm to host (tape worms)
What is a resident?
an established niche at a particular body site (bacteria found in the particular body site)
What are transients?
acquired from the environment and establish themselves briefly (inhibited by resident bacteria or by host immune system) -> inhibited by commensals relationship
What is a carrier state?
a potentially pathogenic organism becomes a resident (streptococcus mutant)
What are opportunistic infections?
when microbes invade a normally sterile location (urinary tract, bladder, abdominal cavity, accessory sinuses) or an area where there are reduced host defenses. Also can occur when an immunologic response opens the way for invasion by flora.
What is the exclusionary effect?
Competition between normal flora and potential invaders. Normal flora can overpower invaders most of the time. When antibiotics take out the normal flora, you lose the competitive advantage.
What is priming the immune system?
presence of microbiota is important for the development for our immune system.
What is differential media?
distinguishes between closely related species of bacteria based on characteristics on the media (color change, colony morphology)…what it looks like on the plate
ex) blood agar
What is selective media?
is used to isolate specific groups of bacteria
- an example of this is the notes media inhibits the growth of one type of bacteria and permits the other - selects for gm + bacteria
(so if you want all gram + bacteria, you put a chemical in that kills only gram neg.)
What is the cytopathic effective?
a test that checks for viral infections which exhibit morphological changes to the cells host tissues
What are immunological tests?
are tests that check for antibody against a virus in the blood. These include precipitation reaction tests (where the antibody and antigen form a precipitate) and hemagglutation (where red blood cells cross link if theres a reaction)
What is nuclei acid detection?
target DNA is bound to a membrane and complementary DNA primers attached to a color producing enzyme are reacted with a membrane. A positive test is indicated by a color producing enzyme or a product formed in the sample.
What are gram stains?
This stains ribonucleic proteins inside cells (Gm + is purple, Gm - is pink)
- crystal violet is the primary stain - everything gets stained purple at first, then the wash step removes the stain from gram negative because of their thing cell wall (stains gram + bacteria purple)
- safranin red is the counterstain (stains gram neg bacteria red)
What is acid fast staining?
this stains the mycolic acid (part of a special cell wall) of acid fast bacteria
- carbol fusión red stains acid fast bacteria red
- methylene blue stains non-acid fast bacteria blue
What are the basic shapes of bacteria?
spheres (cocci) rods (bacilli) - can be straight or bent spirals (spirilla) -vibro - comma shaped -spirochete - corkscrew
What are the common components and structures of all bacteria cells and how do they differ from eukaryotic cells.
all bacterial cells have:
- nucleiod-chromosal DNA
- cytosol (including polyribosomes, proteins ,carbs, inclusion bodies)
- densely packed with ribosomes
- cytoskeleton provides shape to the cell
- plasma membrane (made of phospholipids and proteins)
- cell wall
bacteria are different than eukaryotic cells because they don’t have organelles like mitochondria, nucleus, Golgi, ER
What are the structures found in SOME bacteria (like spores) and what are their functions?
- Flagella or flagellum - motility (gm + and gm -)
- fimbriae (pili) - small hairlike (fimbriae), thicker and longer than fimbriae may be used to transfer DNA (pili) for attachment (gm + and gm -)
- capsule (slime layer) - made of carbs, involved in immune system evasion, can be a nutrient source (gm + and gm-)
- outer membrane (gm -)
- spores (endospores) - help survive hard conditions (gm +)
- periplasm - space between membrane layers (gm -)
What’s the difference between Gm - and Gm ) bacterial cells walls?
Gm neg:
- two membranes and one layer of peptidoglycan (thin) in between
- impermeable outer membrane that has porins (allow diffusion of nutrients and excludes harmful stuff)
- periplasm space - between the two membrane layers and contains lots of important proteins and enzymes needed for survival
- LPS present on outer membrane - has 3 parts
1) O antigen polysaccharide side chain
2) core polysaccharide (similar between species)
3) lipid A (toxin) - if Bacteria is destroyed, these get released into hose and can cause sickness even after the bacteria is dead
Gm pos:
- has a thick (multilayered) peptidoglycan and teichoic acids ( a polymer of glycerol phosphate - function can be for attachment or secretion)
What are the peptidoglycan structural differences in gm +/- ?
- peptidoglycan is a glycan backbone made up of alternating sugars - NAG and NAM
- NAMS are interconnected by a tetrapeptide side chain linked to pentaglycine interbridge
- Gram - uses a DAP, instead of lysine, to connect these two sides
