Zimmer: Microbiology of the Upper GI Flashcards
What are Peyer’s Patches?
Small masses of lymphatic tissue found throughout the ileum region of the small intestine
How many bacteria are in the mouth?
FEW! Until the teeth erupt
What is the normal flora of the esophagus, stomach and small intestine?
Spare–less than 10^4 organisms/ ml of inestinal secretions
How many phyla are found in the stomach?
Four:
Proteobacteria
Firmicutes
Actinobacteria
Bacteroidetes
What is the normal flora of the large intestine?
Microbe rich, “microbiome”!
Anaerobes
Gram-negative rods
Enterococcus – can survive wide range of stressors and enviromental conditions
Spirochetes
What is caries?
infectious disease that causes tooth decay>
Pain, tooth loss, spread of infection
What are RFs for caries?
high-sugar diet, poor oral hygiene, reduced amount of saliva, smoking, periodontal disease
How does caries happen?
Microbial proliferation in the right environment!
Fermentable sugars + acid producing bacteria in a LOW pH–> demineralization
What is the treatment for dental caries?
Drill out decayed area of tooth and put in filling
What is periodontal disease?
Gingivitis (irritation, redness, swelling of gums)
Infectious disease that destroys supporting structures of teeh
What is periodontitis?
Infection of underlying tissues and bones–> localized loss of attachment
Periodontitis can be associated w/:
Heart attack
Stroke
Lung disease
Premature birth or having a baby with low birth weight, in women
What increases the risk of periodontal disease?
Diabetes
What is the MOA of gingivitis and periodontitis?
host immune response causes illness!
What is essential for dental diseases?
plaque/biofilm
What does a biofilm consist of?
two or more species of bacterial microcolonies enclosed in glycocalyx
Proteins
DNA
What is glycocalyx?
polysaccharides
50-95% of biofilm
How is a biofilm formed?
weak adherence of cells to a surface>
stronger adhesion (co adhesion mediated)>
multiplication of cells>
polysaccharide formation>
change in microbial composition over time
Why do bacteria like to life in a biofilm?
Adherence
Protection from the immune system
Protection from antibiotics
Symbiotic (but also anti-symbiotic) relationships
Local conditions of pH, etc, in a normally inhospitable environment
Is plaque bad?
Not if it’s removed regularly, but if not it can trend towards a pathological community
(low pH, sugar rich diet, low saliva flow)
What bugs are associated with good plaque vs. bad plaque?
Bad plaque = s. mutans, lactobacilli
What microbes are normally present in the mouth?
Anerobic organisms
What species play an important role in protecting against dental caries and periodontitis and produce hydrogen peroxide inhibiting growth of other bacteria?
Oral Streptococci
S. sanguinis
S. mitis
- gram positive lactobacilli are also prominent as well as spirochetes
- bacteria associated w/ infection are present but are commensals
Microbes that cause caries are often locate in plaques on tooth surfaces between the crevices of teeth and are usually gram….
POSITIVE
Microbes that cause peridontal disease do their destruction…..
What type of bacteria are they?
BELOW the gum line in the subgingival space
Gram NEGATIVE
Why is it complicated to identify the BAD oral streptococci that can cause peridontal disease?
many oral streptococci are naturally transformable and readily exchange DNA with one another so it makes it harder to conduct a 16s rRNA analysis
What is s. Mutans?
Gram + cocci cat - facultative anaerobic alpha hemolytic opt resistant
What is the difference between a toxin and a VR?
VF: Properties (i.e., gene products) enabling a microorganism to ESTABLISH ITSELF on or within a host and enhance its potential to cause disease. Virulence factors include BACTERIAL TOXIN
Toxin: Microbial toxins PROMOTE INFECTION and disease by directly damaging host tissues and by disabling the immune system.
What are the VF of mutans streptococci?
- Adhesin like surface proteins (AgI/II family) that bind to receptors in the pellicle
- Gtfs (extracellular glucosyltransferases) constituents of the pellicle, synthesize GLUCANS in situ from sucrase. Glucans provide additional S. mutans binding sites
What streptococci represent most of the normal mouth bacteria?
s. mitis
What streptococci represent most of the bacteria involved in tooth decay?
Mutans
What are keystone/red group pathogens?
Not present in large numbers, but the ratio of these bacteria to others is what allows them to be identified
Low-abundance microbes that can orchestrate destructive periodontal inflammation by remodeling a normally symbiotic microbiota into a dysbiotic state”
What are three keystone pathogens?
treponema denticola = spirochete
tannerella forsythia= anaerobic gram negative
Porphyromonas gingivalis**
What gram - rod relates to the severity of a periodontal disease?
Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans
porphyromonas gingivalis
gram - bacillus anaerobic assaccharolytic black pigmented colonies on blood agar bacitracin resistant
P. gingivalis
Capnocytophaga gingivalis
Prevotella denticola
are all….
Microbes involved in periodontal disease
How do you prevent caries and periodontal disease?
- Less sugar in diet – less chance of existing biofilm becoming more pathogenic
- Brush and floss frequently – removes plaque, less chance of harboring bacteria that trigger inflammatory responses
- Fluoride
for remineralization to counteract the effects of demineralization under low pH conditions
Inhibits bacterial glycolysis and pH maintenance enzymes - Increased Saliva flow – sugar free gum
Introduces components of host response
Increases buffering capacity and removes sugars
Return biofilm pH more quickly to resting levels
Is gingivitis reversible?
Yes
What is the treatment for gingivitis?
prevention!
good cleaning and oral care
What is the tx for periodontitis?
Thoroughly clean all surfaces and pockets around teeth to prevent bone damage or prevent further bone damage
How do you treat a milder case of periodontitis?
- Scaling to remove tartar and bacteria
- Root planing: discourage further bacterial growth
- Antibiotics
- Topical is typical
- Oral antibiotic may be necessary in cases of persistent periodontitis despite conventional treatment, when bacteria remain in tissues
What antibiotics may be used to treat a mild case of periodontitis?
amoxicillin
metronidazole
How do you treat severe cases of periodontitis?
Centers around surgical treatments to fix permanent damage:
Flap surgery
Soft tissue grafts
Bone grafts where underlying bone structure is affected
New techniques on the horizon
What disease MC occurs in babies, elderly, immunocompromised?
candida albicans (oral candidiasis)
What disease MC occurs in HIV +
EBV (hairy leukoplakia)
What disease MC is a copmlication of severe tooth infection/periodontal disease?
Bacterial: alpha-hemolytic streptococci, staphylococci and bacteroides groups
Ludwig’s angina
What is the difference between thrush and diptheria/strep throat?
Corynebacterium diptheriae- diptheria
s. pyogenes- strep throat
What is ludwig’s angina?
Skin infection on floor of the mouth, usually results from UNTREATED DENTAL INFECTIONS.
Swelling of infected area may block the airway or prevent swallowing of saliva.
A pt presents w/ breathing difficulty, confusion, fever, neck pain, neck swelling, NECK REDNESS. What does he have?
Ludwig’s angina
How does candida albicans usually grow?
Yeast-like fungus
Grows as yeast/filamentous cells
Can form spores under right conditoins
A pt present w/ creamy white lesions on the tongue and inner cheeks.
Candidiasis
What form of candidiasis is dangerous?
esophageal
How do you diagnose candidiasiss
sxs
can scrape on microscope slide to look for HYPHAE
How do you treat candidiasis?
antifungal
*usuallly topical like clotrimazole or nystatine (swish and swallow)
How do you treat unresponsive cases of candidiasis?
systemic antifungal
FLUCANOZOLE
If someone has candidiasis taht WONT go away how do you treat them?
IV administration of amphotericin B
What can lead to invasive candidiasis?
Untreated candidiasis infections
Candida albicans
fungus hypae forms bacilli non-spore forming non motile
Where does c. albicans usually present?
TONgue!
Where does s. pyogenes usually present?
back of throat
Where does c. diptheriae usually present?
pseudomembarne
What causes leukoplakia?
“white plaque”
smoking/chewing tobacco, other irritations
NOT microorganism
What causes hairy leukoplakia?
EBV in a pt that is almost always HIV +
If a pt presents w/ a fuzzy white patch on the side of their tongue that CANNOT be scraped away.
Hairy leukoplakia
EBV
Herpesviridae DS Linear DNA env HHV- 4
What is the major player in stomach infections?
helicobacter pylori
How is helicobacter pylori normally transmitted?
fecal oral transmission (50% adults are infected)
helicobacter pylori
Bacteria gram - flagellated helix shaped rod microaerophilic catalase and oxidase +
Does H. Pylori always cause infections?
No! only sometimes
50% of adults are infected, but in the third world almost all are
Yet estimated that H. pylori-positive patients have only a 10 to 20% lifetime risk of developing ulcer disease and a 1 to 2% risk of developing distal gastric cancer
Why are pts infected w/ h. pylori usually assymptomatic?
Strains of H. pylori are more or less virulent (pathogen genetics)
Individuals respond immunologically in different ways (host response/host genetics)
Gastric microbiome (a recent concept)**
What can a h. pylori infection cause?
Asymptomatic gastritis that can lead to:
symptomatic gastritis
ulcer
carcinoma
lymphoma
How does h. pylori cause disease?
Toxin production
Host immune response
What causes these sxs?
Gnawing or burning ache in upper abdomen. May become either worse or better with eating
Nausea
Vomiting
A feeling of fullness in your upper abdomen after eating
Gastritis!
Inflammation of the gastric mucosa (transient/chronic)
A pt presents w/ BURNING ABDOMINAL PAIN…
they also have:
Worse when stomach is empty
Flare at night
Often temporarily relieved by eating foods that buffer stomach acid
Disappear and then return for a few days or weeks
Gastric ulcer
Sore that develops on the inside stomach lining
*Felt anywhere from navel to breastbone
How do h. pylori cause disease?
VacA
Adhesins
TFSS and CagA
How do h. pylori survive in the stomach?
Inhibit phagocytic uptake
Inhibit adaptive immune response
Evade killing by reactive oxygen species and nitric oxide
Evade recognition by pattern recognition receptors
How does being able to produce urease help h. pylori to survive in the stomach?
raises the local pH from 2 to about 6 creating some transient buffering
What allows h. pylori to enter the low pH layer?
flagella based motility
What keeps most of the h. pylori swimming in the higher pH zone immediately on top of the epithelial cells?
CHEMOTAXIS based on pH gradient and motility
Why is it important that h. pylori has a subset of cells that adhere to the epithelial cells?
- Adherence allows some cells to avoid mechanical clearance
- Promote invasion and persistence
- Activity of adhesins contributes to inflammation
What are the two main VFs of h. pylori?
VacAa
Cag pathogenicity island= Cag A
What is VacA?
Pore forming cytotoxin that allows leakage of Ca from epithelial celll
What is CagA?
Type 4 secretion system (TFSS) is a NEEDLE through which CagA travels into the host cytosol and affects the proliferative activities, adhesion, and cytoskeletal organization of epithelial cells. The entire system is also highly proinflammatory
How do you cause an ulcer?
- Attract inflammatory cells
- Inflammatory cells cannot kill easily
- Host damages itself by continual, ineffective immune response!
How do you diagnose h. pylori?
Endoscopy + culture
Breath Test
Stool test
Blood test
How do you treat h. pylori?
A week of ‘TRIPLE THERAPY’
clarithromycin + amoxicillin to REMOVE h. pylori
PPI to aid in HEALING of ulcer
What is the gold standard diagnostic technique for h. pylori?
Endoscopy
Guided biopsy>
rapid urease testing, histology, culture
very expensive!
How does a rapid urease test detect h. pylori?
Detects the urease enzyme of h. pylori
How does a breath test detect h. pylori?
Detects radioactive CO2
Good for dx and can confirm cure
Requires a skilled technician
How does a blood test detect h. pylori?
h. pylori Antibodies
* initial diagnosis only, can’t confirm cure
How does a stool ag test detect h. pylori?
Differentiate btwn active and latent infection (serology can only detect exposure)
Why is a stool antigen test great?
easy
good for diagnosis
good for confirming a cure
What cancer are associated w/ h. pylori?
MALT lymphoma
Gastric carcinoma
What is MALT?
Mucosa associated lymphohid tissue caused by LONG TERM INFLAMMATION>
indigestion, heartburn/stomach pain
MALT is a tumor of…
B cells
What is part of the tx strategy for MALT?
antibiotics
What is Gastric carcinoma?
long term inflammation>
indigestion, heartburn>
cancer of the stomach lining (epithelial cells)
H. pylori is a RF in what percentage of gastric carcinoma?
65-80%
