MICROPARA prefinals (lecture and Lab)

• Normal flora: microorganisms normally living on or in the body without normally causing disease.​
• Normal Microbial flora” denotes the population microorganisms, that inhabit the skin and the mucous membranes of healthy normal persons from shortly after birth until death, ( now referred to as the normal microbiota)
• Flora- collective bacteria and other microorganisms in a host 
• Normal (resident) flora are microorganisms that are always present on or in a person and usually do not cause any disease
• Transient or temporary skin flora refers to the microorganisms that transiently colonized the skin. This includes bacteria, fungi and viruses, which reach the hands, for example, by direct skin-to-skin contact or indirectly via objects
• Carrier state- state of being a carrier of pathogenic organisms; that is, one who is infected but free from disease.( e.g.Streptococus pneumoniae)
• Commensal​ an organism that is found normally on those parts of the body that are exposed to, or communicate with, the external environment, eg. Bacteroides fragilis, Staphylococcus epidermidis; the 'normal flora' ​
• • Opportunistic pathogen ('opportunist')​ an organism that can cause infection in individuals with abnormal host defences. *Commensals may be opportunistic
• • Jain Dharma (5th century B.C.)-present-day India postulated the existence of tiny organisms called nigodas, they live everywhere, including the bodies of plants, animals, and people​
• Roman scholar Marcus Terentius Varro in a 1st-century BC book titled On Agriculture in which he called the unseen creatures animalcules, and warns against locating a homestead near a swamp
• Avicenna suggested that tuberculosis and other diseases might be contagious​
• • Akshamsaddin (Turkish scientist) mentioned the microbe in his work (The Material of Life) about two centuries prior to Antonie Van Leeuwenhoek's discovery through experimentation​
• Girolamo Fracastoro proposed that epidemic diseases that could transmit infection by direct or indirect contact​
• • Antonie Van Leeuwenhoek is considered to be the Father of Microbiology. He was the first to discover, observe, describe, study and conduct scientific experiments with microorganisms​
•  John Hogg- led to the naming of a third kingdom called Protoctista​
• Ernst Haeckel –he renamed it the Protista from Proctoctista​
• • Martinus Willem Beijerinck (16 March 1851 – 1 January 1931) was a Dutch microbiologist and botanist. He  often considered one of the founders of virology and environmental microbiology.​
• • Sergei Winogradsk-  was the first to develop the concept of chemolithotrophy and reveal the essential role played by microorganisms in geochemical processes.​
• Felix d'Herelle co-discovered bacteriophages and was one of the earliest applied microbiologists
• The normal flora synthesize and excrete vitamins in excess of their own needs, which can be absorbed as nutrients by the host.​
• Colonization: ↑ Living in the body without causing any harm.​
• The normal flora prevent colonization by pathogens by competing for attachment sites or for essential nutrients. 
• • Resident Flora:​
  • Microbes that are always present on or within body, 90% is S. epidermidis; S. aureus, may be in moist areas, they are commensal​
• • Transient Flora:​
  • Microbes that live in or on  the body for a period of time (hours, days, weeks, months) then move on or die off​
• Symbiosis​ - The relationship between the normal flora and the host
• Three types of symbiotic relationships between bacteria and host​

  1. mutualism​
  2. commensalism​ parasitism​
• Where both the host and bacteria are thought to derive benefits from each other, it is referred to as being mutualism
• • Commensalism - where one organism benefits and the other is unaffected​
• • Parasitism -when one organism benefits at the expense of the other organism​
• Where can we find Normal Flora?​

  • Skin​
  • Eyes (i.e Conjunctiva)​
  • Nose (i.e Respiratory tract)​
  • Mouth (i.e Human Oral Cavity)​
  • Ears​
  • Genitourinary tract​
  • Alimentary canal​
• Sites for the NORMAL FLORA OF THE SKIN

  1.Axilla​

  2. Groin​

  3. Areas between the toes​
• Skin can acquire any transient bacteria from the environment but it either get washed off or die because the skin is dry, has acidic pH, and produce sweat and oil
• • Staphylococcus epidermidis​ - is the most abundant inhabitant of the skin, especially the upper body. ​
• Staphylococcus aureus ​- It is a leading cause of bacterial disease in humans. It can be transmitted from the nasal membranes of a carrier to a susceptible host (immunocompromised
• Propionibacterium acnes​ -

  • Located on greasy areas of the skin, such as the forehead​
  • Can become trapped in hair follicles and cause inflammation and acne​
  • Different species of Propionibacterium can live on the sides of our nose and on our armpits.  ​
• • Aerobic Bacteria:​

      - Present in the outer layer of skin.​

      - Staphylococcus epidermidis (accounts 90%) +    ​

        Staphylococcus aureus
• • Anaerobic Bacteria:   (More than Aerobic bacteria)​

      - Present in the deeper skin layers, hair follicles, and sweat & sebaceous glands.​

      - Propionibacterium acnes.​
• The majority of skin microorganisms are found in the most superficial layers of the epidermis and the upper parts of the hair follicles. 
• the conjunctiva of the eye has ​primarily S. epidermidis, followed ​

  by S. aureus, C. diphtheroids, and​

   S. pneumoniae.​
• • Tears (Lysozyme enzyme), mucus, and oil will protect the conjunctiva of the eye from colonization by more bacteria.​