Normal Microbial Flora in the human body Flashcards
what is the definition of normal microbial flora?
Normal flora are the normal microbes that refer to a population of micro-organisms that inhabit the skin and mucosal membranes of normal healthy individuals
What are the circumstances under which it may cause infection?
● When the commensal moves from its normal area/habitat to another area of the body.
● When the immune system is compromised in some way.
● Secondary to some form of trauma.
● When the balance between organisms of the normal flora is upset by
antibiotic use.
What are the two types of Normal flora?
Resident Flora and Transient flora
Explain what is resident flora?
-Consists out of relatively fixed types of flora regularly found in a fixed area at a given age
-always present
-acquired rapidly during and after child birth
Explain what is Transient flora?
Non-pathogenic micro-organisms which inhabit a particular body part for a limited period
● It is opportunistic, not generally cause disease
● Cause disease when normal flora is destroyed, or body defense weakened
● E.g. in Diabetes and Immunodeficiency
● Some are harmless in its natural residential area but may cause disease in
another area
● E.g E coli in urinary tract
What are the sites in the human body that are normally sterile?
● Urine
● Bone marrow
● Blood
● Cerebrospinal fluid
● Serous fluids
● Tissues
● Respiratory tract
● Mid and inner ear
What are the sites in the human body that have normal flora?
● Skin
● Upper respiratory tract
● Gastrointestinal tract
● Female genital tract
● Conjunctiva of the eye
What is Plaque?
Plaque is a thin film of bacteria attached with polysaccharide matrix, which the bacteria secrete.
What are the advantages of normal microbial flora?
1.Prevent colonisation of potential pathogens.
E.g., skin bacteria produces fatty acids, gut bacteria release bacteriocin and colicin, vaginal lactobacilli maintain acid pH
2. Gut bacteria release Vit B and K
3. Intestinal flora is important in maintaining normal development and of the immune system
4. Antibodies produced in response to normal flora cross react with pathogens, thus raising the immune status of the host.
5. The endotoxins liberated by normal flora trigger alternative complement pathway.
What are the disadvantages of Normal Microbial flora?
1.Potential hazard of spreading which can cause disease in previously sterile body areas
2. Overgrowth occurs when antibiotics is taken and the immunity is compromised 3. Isolation of normal flora causing confusing in diagnosis as its presence might be seen as contamination when a microscopic sensitivity test is done
What is commensalism?
Commensalism is a relationship between species in which one benefits and the other is unaffected.
What is Parasitism
Parasitism is where one benefits, and the other is harmed.
What is Mutualism
Mutualism, a relationship in which both species benefit, is common in nature.
In microbiology, there are many examples of mutualistic bacteria in the gut that aid digestion in both humans and animals.
