Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
Gram Stain
|
- Determines if Gram + or Gram - based on cell wall composition
|
|
Process of Gram Stain
|
01: Add crystal violet
02: Add iodine: all will be purple, Iodine acts as a mordant to set stain 03: Decolorize with alcohol, rinse immediately with water 04: Add safranin Results: Gram + cocci = purple Gram - rods = red (pink) |
|
4 Possible Outcomes of Gram Stain
|
Gram +: Cells retain crystal violent stain- PURPLE; cell wall thick layer of peptidoglycan
Gram -: cell walls do not retain crystal violet because of thin cell wall = PINK Gram Non-reactive: Do not stain or stain poorly (ex. myobacteria -- TB) Gram Variable: Stain unevenly |
|
Salmonella
|
- can live in intestines of animals asymptomatically
- outbreak in eggs, recall of PB |
|
Intensive Agriculture
|
- agricultural production characterized by high inputs of capital, labour, or heavy usage of pesticides or chemical fertilizers
|
|
Intensive Animal Farming
|
- large animals raised on limited land
- require large amounts of food, water, and medical inputs (keep animals healthy in cramped and stressed conditions -- lowers immune systems) - Factory Farming: large indoor confined livestock operations |
|
Contaminated Food: Culprits and Symptoms?
|
- Bacteria, parasites, viruses
- Symptoms range mild to serious: age dependent, type of bacteria, dose, etc. - Harmful bacteria most common cause from raw meat, fruits, and vegetables |
|
What happens in the body after microbes that produce illness are swallowed?
|
01: Incubation Period: bacteria migrates to primary site of infection --> intestines
02: Colonize intestinal wall and release toxins 03: Some are invasive and may penetrate other organs Symptoms depend on type of microbe, usually great overlap: diarrhea, abdominal cramps, nausea |
|
Escheria Coli
|
- more than 700 serotypes identified
- serotypes distinguished by their O and H Ags on bodies and flagella - most do not cause disease in humans - Most serotypes responsible for symptoms from contaminated food are those that produce the Shiga toxin |
|
Shiga Toxin (Stx)
|
Causes harmful E. Coli in humans
Virtually identical to that produced in Shigella dysenteria type 1 One of most potent toxins known to man Likely was transferred by a bacteriophage to otherwise harmless E. coli bacteria |
|
E. coli O157:H7 Disease Symptoms
|
- severe bloody diarrhea
- abdominal cramps - symptoms 2-8 days post ingestion - most likely occur in kids < 5 yrs and elderly (weaker immune systems) - no evidence ABs effective - complication: hemolytic uremic syndrome -- toxin destroys RBCs and damages kidneys, 3-5% mortality |
|
How do humans become infected with E. coli?
|
- oral-fecal transmission
- can live intestines of healthy cattle - toxin requires highly specific receptors on cell surface in order to attach and enter cell - cattle, swine, and deer do not have these receptors and can harbor the toxigenic bacteria asymptomatically and shed them in their feces - meat contaminated during slaughter and butchering, orgs mixed into beef when ground into burger - bacteria also present on cow's udders or on equipment that may get into raw milk (unpasteurized) |
|
Modes of Transmission
|
- undercooked hamburger
- lettuce, spinach - non-pasteurized milk and juices - salami - drinking or swimming in sewage contaminated water |
|
Washing of Leaves (Spinach)
|
Place in vats of lightly chlorinated water, then another washing of more chlorinated water, and then the last wash is a rinse to remove smell of chlorine
Chlorinated water kills 90-99% microbes 12/36 failed to meet chlorination standards past 6 yrs |
|
Biological Role of Pilus
|
Function: Attachment structure
Purpose: exchange genetic info with other bacteria |
|
Structure of E. coli/ Salmonella
|
- Facultative Gram - Rods
- Lipopolysaccharide O side chainsy - Capsule: protects against phagocytosis, is hydrophilic so repels hydrophobic surface of phagocytic cell and also prev AB binding - Pilus, Flagella - Enteric: found in gut Please see slide! |
|
Facultative vs. Obligate Anaerobe
|
Facultative can survive in both presence and absence of O2
Obligate can only survive in presence of O2 |
|
Endotoxins
|
Lipopolysaccharide (LPS) or lipoligosaccharidte
Found outer membrane of various Gram - bacteria Important component in ability to cause disease Activity depends on lipid A component of LPS which is released at cell lysis. |
|
Lipid A
|
Part of LPS that determines of activity of endotoxin
Released at cell lysis Causes many symptoms of Gram - bacterial infections: - complement activation - release of cytokines - fever - shock |
|
Cytokines
|
proteins that act as signals for infection
recruits other immune cells to fight at site of infection and triggers WBCs to release more cytokines |