microbio chapter 21 (all other bacteria) Flashcards
Chlamydia characteristics
- does not have cell wall of peptidoglycan
- cannot grow on its own it needs a host
- grows and multiplies only within vesicle in a host
- typical host: eye or cervical cells
Developmental forms of Chlamydia
- elementary bodies
- reticulate bodies
What kind of disease is Chlamydia
It is a sexually transmitted disease that can also cause blindness
- mother can also pass on to child during vaginal birth
Development of chlamydia cells
- bacteria cell attaches to receptor on a host cell
- EB enters cell via endocytosis on a vesicle
- EB converts to RB inside of vesicle (10hrs)
- RB divides rapidle, many RB’s in same vesicle
- most RBs convert back to EB (21 hrs)
- EB’s are released from host cell (40 hrs)
Chlamydia trachomatis
- has a limited host range (one strain infects mice all others infect humans)
- infects conjuctiva and various mucous membranes
- most common STD in US
- can lead to trachomas
Trachoma
- ocular disease that is the leading cause of nontraumatic blindness in humans
- infection typically occurs during childbirth
Diagnosis of chlamydia
bacteria inside cells from cite of infection or trachoma
Treatment of chlamydia
antibodies for genital and ocular infection
- surgical correction for trachoma deformities
Prevention of chlamydia
sexual abstinence and prompt use of antibacterial agents for blindness
Spirochetes
corkscrewed bacteria with axial filament
Borrelia
- a spirochete
- causes lyme disease
- bacteria is transmitted to humans via tick bite
Tick life cycle
- uninfected eggs become larvae
- larvae feed on animals and become infected with Borrelia and drop off animals after feeding
- Borrelia multiplies in larvae multiply
- In winter, larvae become 8 legged nymphs
- lymph’s feed on humans or animals and introduce Borrelia
- lymphs develop into ticks
- Ticks feed on deer and mate, females can lay uninfected eggs and process repeats
Lyme disease 3 phases
- expanding red bulls eye at infection site
- neurological symptoms and cardiac dysfunction
- severe arthritis that can last years as a result of our body’s immune response
- out body produces antibodies including IgE that can begin to accumulate in our joints
- this leads to degranulation and swelling and damage to our joints
Antibodies in Lyme Disease
- antibiotics do not help because they cannot do anything to accumulated antibodies in joints
- antibiotics can be useful in used in first stage ( does not work otherwise because symptoms of lyme disease are a result of out own immune respone)
- anti-inflammatories are a better option but they expose our immune system more
Why are antibiotics ineffective in treating Lyme disease?
Because the antibiotics cannot access accumulated antibodies and the symptoms of Lyme disease are caused by our own immune response to the bacteria
Prevention of lyme disease
less time in woody areas
immune response of lyme disease
- causes increase in accumulated antibodies because B-cells cannot bind to bacteria as it is in a host cell
- causes an increase in cytotoxic T-cell binding to MHC1 because cytotoxic T-cells can attack cells with bacteria in them
Vibrios
- Vibrios cholerae
- causes cholera which is a disease that causes dehydration
Vibrio cholerae
- causes cholera
- Gram -
- most common to infect humans
- humans are contaminated by contaminated food and water
- common in shellfish or river systems
- rice water soil
- 50% mortality rate in unprepared communities
- otherwise manageable by IV
Cholera toxin
- most important virulence factor
- A-B toxin
Cholera toxin process
- cholera toxin binds to membrane of epethilial cells with binding component
- A component of toxin goes into cell
- A component activates adenylyl cyclase
- adenylyl cyclase makes cAMP
- cAMP stimulates cell to secrete ions
- water follows ions out to dilute ion concentration
- body can lose up to 20L/day
- causes diarrhea if it occurs in our intestines
Diagnosis of cholera
characteristic diarrhea
treatment of cholera
fluid and electrolyte replacement
- antimicrobial drugs are lost in watery stool
Prevention of cholera
adequate sewage and water treatment can limit spread
Helicobacter pylori
- slightly helical, motile
- colonizes stomach of its hosts
- casues gastritis and most peptic ulcers
- produces numerous virulence factors that enable it to colonize in stomach
- can withstand stomach acid if it does the right things
How can Helicobacter pylori live in acidic environment of stomach
- proteins that inhibt acid production
- flagella that allow burrowing into cells
- more neutral pH of inner cells - enzymes that inhibit phagocytic killing and trigger inflammation
- enzymes that break down urease to ammonia that neutralizes stomach
What is the significance of enzymes that break down urease into ammonia?
- ammonia is harmful to epithelial cells and causes open cell damage
- ammonia has a higher pH which causes our mucous membrane layer to break down
pH neutralization for Helicobacter pylori
- ammonia has a high pH
- stomach has a low pH
- this neutralizes the environment for bacteria to grow
End result of proteins made by H. pylori
Inflammation and lack of protection from stomach acid allow pepsin to overwhelm stomach and duodenal membranes
What is Pepsin and in which bacteria is it found?
- found in H. pylori
- it is a digestive enzyme that can overwhelm stomach and duodenal membrane due to lack of protection of stomach acid when H. pylori is present
process of H. pylori
- bacteria utilize their flagella to burrow into mucous layer
- toxins and inflammation cause the layer of mucus to become thin
- Thin layer of mucus allows less protection of our cells
- mucus membrane can be further broken down by ammonia made by H. pylori
- gastric acid can reach our cells and kill them, acid can get to our tissues
- H. pylori can make their way into damaged tissue and create ulcers
- increasing the risk of stomach cancer
Diagnosis/presence
- can be demonstrated by a positive urease test
- biochemical tests proved definitive identification
Prevention
- good hygiens
- adequate sewage treatment
- proper food handling
