1.05 & 1.06 GI Microbio Flashcards
What are the two major bacterial phyla dominant in human gut microbiota?
Firmicutes and bacteroides
Major gram negative residents of the GI tract?
Bacteroidetes
Major gram positive residents of the GI tract?
Firmicutes
Lactobacillus and clostridium belong to what major bacterial group?
Firmicutes
What happens to the diversity of gut microbiota as you move down the GI tract ?
It gets more diverse
The gut microbiome can protect from invaders by sometimes producing what antibiotics?
Colicin and bacteriocin
How do resident gut microbes held in digestion?
Ferment non-digestible polysaccrides, produce SCFA, affect lipid storage, absorption of vitamins (K)
What is the role of the gut micorbome and the immune system?
Initial residents “train” future residents via expression of TLR influencing oral tolerance and even a role in allergies
What two bacterial groups are implicated in serious infections following perforations?
Bacteroides and Peptostreptococcus
Before delivery, the vagina becomes enriched with what bacterial species that pass onto neonates?
Lactobacillus
At what age does the gut microbiome stabilize once influenced by diet, environments and genetics?
3
What can disrupt immune system development and is associated with higher rates of asthma, obesity, diabetes?
Caesarean delivery and not breastfeeding (maternal antibiotic overuse)
Why is breast milk beneficial?
Molecules that mother can metabolize for them ,SCFA promote satiety, lipid/sugar metabolism produces better health
An adult like microbiome in an infant is associated with?
Childhood obesity
What neurological disorders is the microbiome implicated in?
Autism, depression, MS
Gram positive rod, endospores
Clostridium difficile
Most common nosocomial cause of diarrhea in the US?
C. Difficile
Causative agent of pseudomembranous colitis?
C. Diff
C diff requires what enterotoxin necessary for its pathogenesis targeting epithelial cells?
TcdA + TcdB
(A-B Toxin)
What will you see in a colonoscopy of patients with pseudomembranous colitis?
Raised yellow plaques and coalescing pseudomembranes
What is an extremely effective treatment for persistent diarrhea due to a C diff infection (and the protocol for multiple recurrences)?
Fecal microbiota transplant
What is the go to diagnostic detection of for C diff infection?
ELISA or Westernblot of diarrhea (although PCR more Sn)
Typical antibiotic treatment for c diff?
Metronidazole or Vanc
Gram negative bacillus “spiral” shaped motile
H. Pylori
What are the H pylori virulence factors?
Mucinase (penetrates mucus layer), Urease (ammonia cloud), CagA (pathogenicity)*
H pylori can cause gastric inflammation that can lead to what pathologies?
Chronic gastritis, duodenal stomach ulcers, stomach cancer
What is the potential downside of treating an H pylori infection?
Increased risk of GERD and asthma
What is unique about H pylori that explains its route of transmission?
Humans are the only reservoir so fecal-oral or oral-oral transmission
What is interesting about the age of the patient when first colonized by h pylori?
The older someone is when first colonized the greater the likelihood of ulcers
What H pylori virulence factor is associated with gastric inflammation and gastric cancer?
CagA
What does CagA do?
Interacts with MAPK cascade when phosphorylated modifying the host cell shape and cell cycle
What happens to the gastrin production in person colonized by H pylori?
Increased production to increase acidity ( decreased pH)
Where does H pylori grow?
Mucosal layer
(breaks down tight junction and lose epithelial cells that can lead to inflammation and ulceration)
What is the most significant contributed to non-drug cases of gastritis, gastric ulcers, and idiopathic duodenal ulceration?
H pylori
H pylori colonized individuals less likely to have… (note more studies needed)
GERD, esophageal Carcinoma, Barrett’s esophagus, less diarrhea, asthma
What is the quickest and most common way to diagnose an H pylori colonization?
Urea breath test
Treatment for asymptomatic patient who test positive for H pylori?
None
Treatment for asymptomatic patient with H pylori but FH of gastric cancer?
Treat!
Combo antibiotic (amoxicillin and clarithromycin) + PPI
What is the difference a probiotic and a prebiotic ?
Pro = live organism
Pre = non-digestable oligosaccharide
Concerns about probiotics?
Not regulated, no manufacturing standards, not required to show efficacy
What is a synbiotic?
Prebiotic and probiotic combo
Current research synbiotic trial resrecah is promising as it has found that it may reduce risks of:
Lower Serious infections (sepsis), lower respiratory tract infections
