Bacterial Pathogenesis Final Part 2 Flashcards
What is the microbiota?
- hundreds of organisms that colonize a host
- bacteria are the most abundant, then fungi and archaea
Is there a a single healthy adult human microbiota?
No
What is the difference in the microbiota of c-section babies vs natural birth babies?
C-section: disrupted transmission of maternal bacteroides, high level of colonization by opportunistic pathogens (enterococcus, enterbacter)
What is the difference between resident and transient microbiota?
Resident: life-long
Transient: just passing through, can’t stay because of competition, or elimination by immune system
What are the types of relationships between bacteria and host?
Mutualism, commensalism, parasitism
What is microbial antagonism?
The inhibition of one bacterial organism by another
What are some nutritional benefits of bacteria?
Synthesize vitamin K, converts steroids into the active form or a form that can be absorbed by the host, break down food that is normally indigestible
Where is the microbiota located?
Any body part exposed to the environment (mostly skin, resp, GI tract, urogenital tract)
What are common bacteria found on the skin?
Propionibacterium acnes, staphylococcus aureus, staphylococcus epidermidis
What bacteria are commonly found in the oral cavity?
Streptococcus mutants
What bacteria are commonly found in the GI tract?
Helicobacter pylori, clostridium difficile
Why is the skin a good place for bacteria to grow?
Acidic, salty, dry. Sebum contains lipids, amino acids, lactic acid and is used as nutrients
Is Propionibacterium acne’s gram pos or neg? Is it aerobic or anaerobic? Where does it live? How does it cause inflammation?
- gram pos
- aerotolerant anaerobe
- lives at the base of a hair follicle
- fermentation products lead to skin inflammation
What phylum does staph belong to?
Firmicutes
Is S. aureus found in all people? How about S. epidermis? What kind of infections do they cause?
S. Aureus: some people, can cause skin infections, pneumonia or sepsis
S. Epidermis: all people, forms a biofilm and can cause catheter infections and introduced into blood
What do Streptococcus mutants synthesize? What promotes this?
Dextran, sucrose
What is the purpose of glucan binding proteins?
Dextran binds and forms a biofilm
Which parts of the respiratory tract are sterile?
The sinuses and lower resp tract
Where is most of the bacteria in the GI tract?
The large intestine
What kind of bacteria live in the stomach? How do they move?
Fermentitive bacteria live in gastric epithelium mucus; spiral flagella propels into the stomach lining
What are the virulence factors of H. Pylori?
- flagella
- urease: gastric mucosal injury and gastric acid neutralization
- LPS: adheres to host
- T4SS: injects effectors
- exotoxins/enzymes: gastric mucosal injury
What is an endospore?
Some of the bacteria go from vegetative state into a resting state, to protect the genome until there are more favourable conditions
What are the virulence factors for C. Diff?
- Bile-tolerance
- flagella
- cell-wall proteins
- Cathelicidin resistance
- O-nitrosylation
What bacteria is in the vagina?
Lactobacillus
What is a biofilm?
Bacteria stuck to a surface and enmeshed by slimy EPS matrix
What is EPS made out of?
Polysaccharides, proteins, DNA
How many species are biofilms made out of?
Sometimes 1, sometimes more than 1
What are the requirements for biofilm formation?
- flagella
- be able to attach to a solid substrate
- be able to move on the substrate
- have cell density signals
How are biofilms resistant to treatment?
- EPS forms a mesh barrier
- the inside cells are hard to access by drugs and immune cells
- inside cells have no access to nutrients so they are resistant to antibiotics
- the inside cells persist and repopulate
What are the infections caused by P. Aeruginosa?
Skin infections in burn patients and lung infections in cystic fibrosis patients
