Normal Microbial Flora in Human Body

• Normal Microbial Flora


  The population of microorganisms that inhabit the skin and mucous membranes of healthy normal persons from shortly after birth until death
• Resident (normal) flora


  Microorganisms that are always present on or in a person and usually do not cause any disease
• Transient (temporary) flora


  Microorganisms that transiently colonize the skin, including bacteria, fungi and viruses
• Carrier state


  State of being infected but free from disease
• Pathogen


  An organism that can cause infection in individuals with normal host defences
• Commensal


  An organism that is found normally on those parts of the body that are exposed to, or communicate with, the external environment
• Opportunistic pathogen ('opportunist')


  An organism that can cause infection in individuals with abnormal host defences
• Pathogenicity


  The ability of a parasite to inflict damage on the host
• Virulence


  Measure of pathogenicity in a microorganism
• Host


  An animal or plant on or in which a parasite or commensal organism lives
• Infection


  Situation in which a microorganism is established and growing in a host, whether or not the host is harmed
• Disease


  Damage or injury to the host that impairs host to function
• Colonization


  Living in the body without causing any harm
• Bacteriocin


  Ribosomally synthesized antibacterial peptides/proteins that either kill or inhibit the growth of closely related bacteria
• A fetus is sterile when born (No Normal Flora), then newborn start having the normal flora from its mother, air, food and the environment
• Our internal organs are sterile like the spleen, liver, pancreas, bladder, Cerebrospinal Fluid, and blood unless during infection
• Normal flora differ from one human to another depending on age, diet, and geographic habitat
• The human gut alone contains on average: 40,000 bacterial species, 9 million unique bacterial genes and 100 trillion microbial cells
• The human body contains around 1013 cells, whereas the human physical structure is around 1014 bacteria. One-fourth of fecal weight consists of bacteria
• When the number of resident normal flora is greatly reduced, opportunistic microbes can easily cause infections in these areas e.g. Candida Albicans that cause candidiasis
• It has been calculated that a human adult houses about 1012 bacteria on the skin, 1010 in the mouth, and 1014 in the gastrointestinal tract
• They are in most cases beneficial to us because they protect our bodies from diseases by preventing the overgrowth of harmful microbes
• 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
• Mutualism


  Where both the host and bacteria are thought to derive benefits from each other
• Commensalism


  Where one organism benefits and the other is unaffected
• Parasitism


  When one organism benefits at the expense of the other organism
• Role of Microbiologist


  Accurate diagnosis: by Rapid/ quick, meaningful reporting
• Role of Physician


  Proper treatment with antimicrobial regimen/ standard guidelines by avoiding overuse*/misuse of antimicrobials * by treating pathogen, NOT the normal flora!!
• Factors that affect normal Flora

  • Weather
  • Age
  • Personal hygiene
  • Sex
  • Diet
  • Standard of living/nutritional status
  • Health
  • Hospital stays
  • Clothing
  • Environment
• Normal Microbial flora


  The population of microorganisms that inhabit the skin and the mucous membranes of healthy normal persons from shortly after birth until death
• Normal (resident) flora


  Microorganisms that are always present on or in a person and usually do not cause any disease
• Transient or temporary skin flora

  Microorganisms that transiently colonized the skin, including bacteria, fungi and viruses
• Carrier state


  State of being a carrier of pathogenic organisms; that is, one who is infected but free from disease
• Pathogen


  An organism that can cause infection in individuals with normal host defences
• Commensal


  An organism that is found normally on those parts of the body that are exposed to, or communicate with, the external environment
• Opportunistic pathogen ('opportunist')


  An organism that can cause infection in individuals with abnormal host defences
• Pathogenicity


  The ability of a parasite to inflict damage on the host
• Virulence


  Measure of pathogenicity in a microorganism