Micro of the Upper GI Part I Flashcards
What are four ways to think about how microorganisms cause disease?
- Toxin production
- Host immune response
- Microbial proliferation and invasion
- Cancer
How does toxin production lead to disease?
Bacteria release toxin that causes illness
How does the host immune response lead to disease?
It’s the response of the host to the microbe that causes illness
How does microbial proliferation and invasion lead to disease?
Growth and spread of microbes that cause damage that is significant in illness.
How do microbes use promote cancer?
Microbe promotes uncontrolled proliferation of cells and host organisms
What are the GI system defenses in general?
Epithelium, Mucus, Peristalsis
What are the GI system defenses in the mouth?
Saliva (lysozyme, IgA, etc.), normal flora
What are the GI system defenses in the stomach?
Acid, normal flora, ?
What are the GI system defenses in the Intestine?
Peyer’s patches, Normal flora
What is the normal flora?
Par to the microbiome - the ecological community of commensal, symbiotic and pathogenic microorganisms that share our bodies
What are Peyer’s patches?
Small masses of lymphatic tissue found throughout the ileum region of the small intestine.
When do we have “clean” mouths without flora?
In babies before teeth erupt.
What is known about the normal flora in the Upper GI tract (esophagus, stomach, duodenum, jejunum, and upper ileum)?
Normally contains sparse microflora
- Bacterial concentrations is less than 10^4 organisms/ml of intestinal secretions
- Four phyla in stomach: Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes
- May still be important
What is known about the normal flora in the large intestine?
- Microbe rich, “microbiome” studied here
- Anaerobes
- Gram-negative rods (proteobacteria, etc.)
- Enterococcus, gram-psotivie cocci, facultative anaerobes can survive wide range of stressors and environmental conditions
- Spirochetes
What are the main parts of a tooth?
- Enamel
- Dentin
- Pulp
- Cementum
- Periodontal membrane
- Nerve and blood supply
- Crown
- Root
What is the infection of a Dental Carie? What can it cause?
Infectious disease that causes tooth decay. Can lead to pain, tooth loss, spread of infection.
What are risk factors for Dental Caries?
- High-sugar diet
- Poor oral hygiene
- Reduced amount of saliva
- Smoking
- Periodontal disease
What is the incidence of Dental Caries worldwide?
Common
How are Dental Caries a health disparities issue?
AI/AN children have the highest prevalence of early childhood caries among any population group in the United States.
What is the prevalence of untreated decayed teeth in people without a high school education and low income people?
- Double the incidence in people without a high school education
- Much higher incidence in low income people, higher incidence in medium income people, lowest incidence in high income people
What is the mechanism behind Dental Caries?
Fermentable sugars + Acid producing bacteria —(add pH)—> Demineralization
What is the treatment for Dental Caries?
- Do not want to let caries grow
- Can involve whole tooth and cause infection
- Drill out decayed area of tooth and put in a filling
What is Periodontal Disease?
Infectious disease destroying supporting structures of teeth (you loose teeth from this condition)
How much of the population does periodontal disease effect?
Affects more than 30% of the population worldwide
What is the mild common form of periodontal disease? What does it involve?
Gingivitis. Involves the gums.
What are the symptoms of Gingivitis?
- Irritation
- Redness
- Swelling
- Inflammation
What can happen to teeth in periodontitis?
Localized loss of attachment
What is Periodontitis defined as?
Infection of underlying tissues and bones (under teeth)
What conditions is having periodontitis associated with?
- Heart attack
- Stroke
- Lung disease
- Premature birth or having a baby with low birth weight, in women
- Diabetes
By what mechanism are microorganisms causing disease in gingivitis and periodontitis?
Host immune response
What is essential for all dental diseases?
Plaque - a biofilm
What is a biofilm?
Two or more species of bacterial microcolonies that are enclosed in a glycocalyx
What are the components of a biofilm?
- Glycocalyx is composed of polysaccharides and constitutes up to 50-95% of the biofilm
- Other components of the biofilm include proteins and DNA
- Can be hundreds of species in a biofilm
How is a biofilm formed?
- Week adherence of cells to a surface
- Stronger adherence, likely co-adhesion mediated
- Multiplication of cells
- Polysaccharide formation
- Changing of microbial composition over time
Why would a bacteria want to live in a biofilm?
- Adherence
- Protection from immune system
- Protection from antibiotics
- Symbiotic (but also anti-symbiotic) relationships
- Local conditions of pH, etc., in a normally inhospitable environment
Is all plaque bad?
It can maybe be neutral…but when its regularly removed, it cannot trend toward a pathological community
What are environmental changes that cause caries?
Caries are a result of changes in the environment due to acid procession from the fermentation of dietary carbohydrates, which selects for acidogenic and acid-tolerating species such as mutants streptococci and lactobacilli.
What species of bacteria are acidogenic and acid-tolerating?
- mutans streptococci
- lactobacilli
How can disease be prevented with dental caries?
Disease could be prevented not only by targeting the putative pathogens directly, but also be interfering with the key environmental factors deriving the deleterious ecological shifts int he composition of plaque biofilms.
What type of organisms predominate in the mouth?
Anaerobic
What bacteria play important roles in protecting against dental caries and periodontitis? How do they do this?
Species of oral streptococci. Producing hydrogen peroxide which inhibits the growth of other oral bacteria.
What are the oral streptococci that protect the mouth?
S. sanguinis, S. oralis, S. gordonii, S. mitis
What is important about the Streptococcus mitis group?
It’s a nonpathogenic commensal organism
Other than streptococci, what other bacteria are normally present in the mouth?
- Gram + Lactobacilli are also prominent
- Also spirochetes
- Bacteria associated with pathogenic infection are also often present, but at lower amounts. (still considered “commensals”)
