Normal Flora Flashcards
What is the normal flora?
Population of microorganism that inhabit the skin and mucous membranes of a healthy person
What are the 2 types of normal flora?
- Permanent–fixed population, can easily re-establish itself.
- Transient: temporarily, short duration, could be non-pathogens or pathogens
How does the flora differ between age groups?
- Healthy fetus : sterile
- Initial flora: during / after birth- environmental sources (air, dust, food, water, personal contact, clothing etc.)
- Healthy baby of 48 hours and adults- Stable flora
Why is a healthy normal flora important?
- Immune System:
- Balance of TH1 and TH2 cells
- Cross reaction of flora antibodies with related pathogens
- Development of lymphoid tissue such as Peyer’s patch
- Nutrients:
- Synthesis of vitamin K and B by enteric and lactic acid bacteria
- Interference:
- Prevent colonization pathogen (colonization resistance)
- Antagonice other bacteria
- Therapeutic:
- Probiotics (fecal transplant)
What are the harmuful effect of a disrupted normal flora?
- Endogenous diseases
- Infective endocarditis-Viridans streptococci
- UTI by Escherichia coli
- Compromised host defense/opp. infection:
- Diabetes, Leukemia, Chemotherapy etc.
- Transfer to new host
- Chronic diseases:
- IBD, Autoimmune, Allerges
- Obesity
- Psychiatric and neurological disorders.
- Brain-gut connection
- Possible source of carcinogens
- Produce from the compounds ingested(e.g Artificial sweetner cyclamate- bladder carcinogen)
- Competition for nutrients
- Bacteria use nutrients before absorbtion
In the absence of disease, within the body what is considered sterile?
Lower respiratory tract
Blood
Spinal Fluid
Internal Tissues
Normal Floral antibodies protect angainst which microorganism?
Meningococci Polysaccharide
What are the microorganism components of the skin?
- Staphylococcus epidermidis- hospital infections: catheters, artificial heart valve/prosthesis
- Propionibacterium acnes- follicles anaerobic bacteria
- Staphylococcus aureus- enters piercing site. cause of infective endocarditis in drug addicts
- Candida albicans- yeast –IV catheters, IV drugs; infection of moist skin
What are the microorganism components of the mouth?
-
Viridans Steptococcus:
- Steptocuccus mutants- dental plaque. bioflim. demineralizes enamel
Bacterial endocarditis and abscess in brain or liver: entry in blood stream (eg.during Tooth extraction)
- S.salivarius, S. mitis, S. sanguis, S. anginosus etc..
What are the microorganism components of the nose?
Staphylococcus aureus – 20% carrier rate –
source of outbreaks in hospitals
What are the microorganism components of the throat?
- Viridans streptococcus: Streptococcus pyogenes (beta hemolytic) (10-15%) – cause bacterial pharyngitis
- Streptococcus pneumoniae
- Neisseria meningitidis and
- Haemophilus influenzae
What are the microorganism components of the lower repiratory tract?
STERILE
Aspiration of upper tract flora – cause infection in the lung
What are the microorganism components of the stomach?
Helicobacter pylori – Up to 30% of population
- gastric ulcer
Lactobacillus
What are the microorganism components of the colon?
1011 – 1013 cells/g
20% of feces compozed of bacteria
- Bacteroides fragilis: Gram negative strict anaerobe. peritonitis-perforation.
- Escherichia coli: Gram negative, facultative anaerobe, UTI
- Bifidobacterium, Lactobacillus – used as probiotics
Why is disturbance of the normal flora with antibiotics bad?
Proliferation of antibiotic resistant members:
- Enterococcus spp
- Pseudomonas spp
- Candia spp
- Clostridium difficile : spore former- pseudomembranous colitis
