Bacteria Toxins Flashcards
Toxoid
Altered or inactivated toxin. Either by heat or chemical means. (Altered referred as toxoid.
Toxemia
In a condition called toxemia, toxins enter the blood stream and are carried to other parts of the body, including sites that may be far removed from the site of infection.
Antitoxin
The body protects itself with antitoxins, which are protective molecules called antibodies that bind to the toxin and neutralize them.
Exotoxin
Many organisms secrete exotoxins that are central to their pathogenicity in that they destroy host cells or interfere with host metabolism.
Exotoxins are of 3 principle types:
Cytotoxins, neurotoxins, enterotoxins.
Cytotoxins
Which kill host cells in general or affect their function.
Neurotoxins
Which specifically interfere with nerve cell function.
Enterotoxins
Which affect cells lining the gastrointestinal tract.
Cytotoxin
Hemolysis toxin
Diphtheria toxin:
Is an endotoxin secreted by corynebacterium that causes Diptheria.
The toxin causes the disease Diptheria in humans by gaining entry into the cell cytoplasm and inhibiting protein synthesis.
Toxins
Harmful substances made by some pathogenic bacteria species
- cause tissue injury/ trigger host immune response
- normally blood or lymph soluble; are systemically distributed.
Exotoxin
Synthesized and secreted by gram + or - bacteria; part of their normal growth and metabolism
Coded plasmids or phase DNA
Anthrax toxin
3 components:
Antigen
Lethal factor
Edema factor
Shiga toxin
Potent cytosol toxin made by Ecoli 025H7
Part A enters into cell
Endothelial cells/ cells that covers blood vessels.
Reacts with :Ribosomes
Stops: protein synthesis
shiga toxin
Hemolytic uremic syndrome
Tabac break up in the tiny blood vessels.
Result in: anemia, kidney failure accompanied by paralysis and nervous system injury signs.
Enterotoxins:
Alters functioning of the gastrointestinal cell lining, cause intestinal disterbances.
Colleria a Toxin
Botulism toxin
Toxin AB
B attaches to specific receptor on motor nerve endings.
A- enters inside, becomes an active peptidade enzyme that degraded a beside protein.
Bacteria Lag phase
- no appreciable change in cell number; extend from few hours to few days
- cells exhibits intense metabolic activity increased synthesis of proteins, cell wall component, phospholipids
- bacteria takes a long time to transfer the lactose- to breakdown lactose.
Log phase
- period of rapid growth at the exponential rate
- cells are metabolically active; cells divide at constant rate
Generation time- time it takes population doubling( 20 start after 20 min= 40 cells) is well maintained and is constant
- plot is straight line; cells in mid exponential phase are valuable for researchers.
- the most sensitive in this phase- are more susceptible to anti microbial drugs that interfere with metabolism, such as enthromycin and drugs that interfere with the formation of cell structures.
Chemostat and it’s important
Researchers and industrialists can continuously maintain a particular phase of microbial population growth by using a special culture devise called a chemostat
Chemostat
The cells in the log phase of growth ( that maintains cells in the log phase)
- in late valve ( fresh medium)
- outlet valve ( dead cells and used medium is removed)
Stationary phase
- growth rate slows; new cells produced at same rate the old cells die.
- limited growth conditions due to,
1. Consumption of essential nutrients
- Waste products accumulation at toxic level
- pH changes ( contributed by actively growing cells)
Energy and nutrients-
Death phase
- population enters this phase when cells dying exceeds number of new, viable cells
- progressive in some: alternatively called as the logarithmic decline phase
- continues until small proportion of the cells remain or population dies out entirely
- endospores are formed
Nutrient Uptake
Passive process
Active process
Passive process
- substance movement is from high indentation to region of low concentration.
- no expenditure of cellular energy.
Active process
- functions when bacteria are in low nutrient environment
- there is expenditure of cellular energy.
Exotoxin
- Cytotoxin: kills/ affects host cell functions;
Hemolysin toxin- binds to cholesterol epithelial cells - Diptheria toxin- that targets binds and inactivated a eukaryotic protein synthesis.
- Anthrax toxin- 3. Component toxin
Antigen
Lethal factor
Adela factor
How are fungi isolated
SAB is used for fungi isolation
High salt and sugar w/pH acidic ate favors fungi isolation innovates bacteria.
Capnophiles
Are organisms such as Neisseris Gonorrhea that grow best with a relatively high concentration of carbon Dioxide in addition to low oxygen levels.
Streptococcus pyrogens
Completely digests red blood cells, producing around its colonies clear zones termed beta hemolysis.
Thayer Martin media (TM)
Used to isolate and cultivate of gonorrah from clinical samples. Medium contains a contain of antimicribial agents.
SAB-sabouraud’s media
Used for fungi isolation high salt and sugar w/ low pH
Acidiciate
Favors fungus isolation innovates bacteria
Alpha hemolysis
Secretes by bacteria- incomplete destruction.
Beta hemolysis
Due to beta hemolysis lysime
Complete destruction of red blood cells
Gamma hemolysis
Streptoccus
No defect on the red blood cells
Bacteria growth curve
A graph that plots the numbers of organisms in a growing population over time is known as a growth curve.
Generation time
The time required for a bacterial cell to grow and divide is its generation time. Viewed another way generation time is also the time required for a population of cells to double in number.
Generation times vary among population and are dependent on chemical and physical conditions.
Chemostat
A chemostat maintains a culture in a particular phase, typically log phase.
Make it possible the study of microbial population growth at steady but low levels such as might be found in bio films.
In which step are pathogens are sensitive to drugs?
The most sensitive that the bacteria are
Tetanus toxin
Lock in of the diaphragm muscles at a constant state of relaxing.
Innovated release felicitous neurotransmitter.
No oxygen=death
Helicobacter pylori
Causes peptic ulcer
Perforation pearling of the GI system
Stomach- gastric ulcer
Virulence factors: proteins that innovates acid secretion
Adhesions that promotes or facilitates adhesive.
Pathogenesis: attached to stomach membrane
Attaches to membrane of stomach lining cells and multiplies
Mucus layer thins due to inflammation toxin secretion
Loss of mucus layer results in stomach lining vulnerable to perforation by gastric juice
Once compromised, bacteria invades underlying muscle tissues and blood vessels.
Cells are phagocytosed survived action of catalase and SOD
Risk: smokers, stress, alcohol, spicy food, family history of upsets
Transmission:oral fecal pathway
Shigella
Non motile
Rod shaped bacteria
- common undeveloped countries
Symptoms: fever, abdominal cramps, diarrhea and occasionally bloody stool
Diarrhea is self limiting: treatment is supportive care in most instances.
Secretes enterotoxin, transfers via: type 3 secretion
S. Dysteriae makes the shiga toxin enterotoxin
/ Diagnosis: presence of Shigella in patient stool.
Shigella steps
- Attaches to epithalial cells, induces uptake
- Triggers actin polymerization and rearrangement, enters adjacent cells
- Bacteria escapes/ spills into blood stream, phagocytosed and destroyed
Bacteremia is a complication under rare condition.
Shiga like Toxin
Made by S, dysenteriae
Potent cytotoxic; chromosomally coded AB toxin
Causes,
- stops translation, leads to host death
- hemolytic uremic syndrome
A part- endothelial cells that lines blood vessels particularly of kidneys- ribosomes- halts protein synthesis.
Injectosomes
20 different proteins integral proteins that makes up the injectomes
Central: hollow tube for the toxins
- propel the bacteria
- propels forward by injecting in….
salmonella
Causes typhoid fever and salmonellosis
Motile
Gr.(-) with peritrichous flagella
Bacteria present in all vertebrate reptiles intestine
- not part of human intestinal microflora
Infection: via food and water contaminated with carrier’s feces
Carrier remains a symptomatic
- tolerant to stomach acidic condition, attaches via intestine wall
Pass through intestinal cells into blood stream phagocytosed but avoids digestion
Released through intestinal cells into blood stream, phagocytosed but avoids digestion
Released later to reinfect spleen, liver, gall bladder.
Cholera
Caused by Vibri cholerae
Gram (-) bacteria with polar flagella
Causes rice water poop which is watery, colorless, odorless with specks of mucus
(That looks like rice grain)
Distributed worldwide; prefers warm, salty alkaline water but can survive in freshwater too.
In salt water forms biofilm community
Freshwater disintingrates
High infective dose
2 strains are important:associated with cholera pandemics
0139 Bengal strain
Other strains are associated with mild gastroenteritis
Virulence factor: cholera toxin and is secreted by the type3 secretory system
Simple diffusion
- small or lipid soluble substances easily moves down concentration gradient
- movement continues until equilibrium is reached
Facilitated diffusion
- used by molecules unable to diffuse or fails to dissolve across lipid bilayer
- use channel protein
Simple- no energy involved
F.D-facilitated by the intrigral protein
Is saterable carrier molecule filled up it will accept a new molecule
Active transport
Involves substances enemy from outside to inside
Group translocation
Cells picks substance even though they are in lower consultation outside.
- substance altered during transport; prevents from leaving cell
