Oral Flora I&II Flashcards
What is resident flora?
Consists of a relatively fixed number and types of microorganisms regularly found in a given area at a given age. If disturbed it promptly re-establishes itself. Rapidly acquired during and after birth. Changes continuously throughout life.
What is transient flora?
Consists of non-pathogenic or potentially pathogenic microorganisms that inhabit the skin or mucous membranes for hours, or days.
Occurs when there is a perturbation in resident flora.
What is a mutualistic relationship?
Microbe and host both mutually benefit e.g., microbe might get food resources and the host gets benefits from the waste products of the microbe could be nutrients
What is a commensalistic relationship?
Microbe benefits but the host gets no benefit or harm. E.g, staphylococcus on the skin benefits from our skin but has no effects on humans.
What are a pathogenic/parasitic relationship?
Microbe benefits but the host is harmed. Disease situation. E.g. tuberculosis bacterium in human lung benefits but humans get disease
What are opportunist pathogens?
Bacteria that are normally not causing disease, but if something changes in the environment then these bacteria can change, become pathogenic and cause disease.
When can opportunist pathogens cause disease?
In an immune compromised individual
When they change from their usual location
What is a dysbiosis?
When the healthy micro flora environment changes to a disease associated environment
What can cause a dysbiosis?
Abuse of antibiotics can destroy beneficial bacteria and promote growth of not beneficial bacteria
Radiation can kill off resident micro flora
Surgery might allow entry of bacteria
Use of immune suppressors may prevent immune system from keeping a balance
Hormones
Acquired immune deficiency
What sites in humans should never have bacteria in them and are sterile?
Blood brain, muscles, CSF
What is the mouth like in a healthy state?
Balance of healthy bacteria. Symbiosis between microbes and us.
What factors might alter the balance of microbes and humans in the mouth?
Inappropriate diet causing decay
Inadequate plaque control due to bad oral hygiene leading to disease associated flora
Impaired saliva flow
Altered host defences e.g. immunosuppression
Lifestyle risk factors e.g. alcohol and smoking
What are the 2 major diseases caused by dysbiosis in the oral cavity?
Caries and periodontal disease
Can also lead to systemic diseases
What bacteria are part of the healthy micro flora?
Streptococcus, actinomyces, Fusobacterium etc
What bacteria cause caries?
Particularly Strep. mutans and lactobacilli
How do the caries causing bacteria cause caries?
Produce acids that erode enamel
Tolerate their own acids so survive
Form sugars too which make a gloopy mass for bacteria to live in
What bacteria are found in periodontal disease?
Porphyromonas gingivalis, Tannerella forsythia
What do periodontitis causing bacteria do to produce periodontitis?
Produce enzymes like proteases and cytotoxic which are immune modulators and cause an inflammatory response
Where can pathogens be acquired from?
Within the body
Other people
Animals/animal products
Anywhere on planet eg soil water airborne
Hospital acquired
Where do periodontitis causing bacteria come from?
Within us but usually in small numbers so don’t cause disease. If conditions change and they multiple and produce virulence factors then they overgrow and cause disease.
